Starting template used for provisioning Oregon agency sites

Oregon Noxious Weed Profiles

The noxious weed policy and classification system includes Oregon’s official noxious weed priority list as designated by the Oregon State Weed Board (OSWB). Oregon Department of Agriculture has compiled profiles of the weeds listed by OSWB. Profiles include information about the weed, images, and locations in Oregon.

Basic Info: African rue
Peganum harmala
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Family: Caltrop Description: African rue is a multi-branched and bushy perennial. It is a succulent plant, with bright green alternating leaves that are smooth and finely divided with long, narrow segments. Plants grow 1.5 feet tall and 3-4 feet in diameter. Flowers are white with five individual petals and are present in spring to early fall. Fruit is located in a leathery capsule 2-4 celled that contains 45-60 seeds. Seeds are angular, dark brown and have a distinctive smell. When crushed, the stems also have a disagreeable odor. The base of this plant is woody and roots can branch and reach 20 feet in depth. Habitat: African rue prefers disturbed environments such as roadsides, fields and rangelands in desert and semi-desert areas. It is often found in soils with high salinity and most parts of the plant contain allelopathic chemicals that reduce growth of other vegetation. Impacts: African rue contains at least four poisonous alkaloids. It is toxic to people and livestock. The seeds and fruit of the plant are the most toxic part with a lethal dose being 0.15 percent of an animal's body weight. Young leaves are less toxic then seeds with a lethal dose of about 1.0 percent of the animal's weight, while mature leaves are less toxic. Dry leaves are apparently nontoxic. This noxious weed is extremely drought tolerant and displays robust vegetative growth expanding into desert rangelands replacing native plants like salt brush and grasses. It has a competitive advantage over native plants as it germinates earlier in the spring. Distribution in Oregon: The first documented site in Oregon was 1967 in Crook County. In 2008, African rue was identified in Harney County. For a collection of spatial information on the distribution of this plant in Oregon, go to Oregon WeedMapper Biological controls: Biological control agents are not used on "A" listed weeds in Oregon. This weed is being managed for eradication or containment.
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Basic Info: Armenian blackberry (Himalayan blackberry)
Rubus armeniacus (R. procerus, R. discolor)
Designation: List B
Documents: Profile Distribution
Introduction: Armenian blackberry grows as a robust, well-armored, perennial vine producing large impenetrable thickets especially along valley floors. Deep-growing woody roots yearly produce spine covered, reddish stems often extending more than 20 feet per season. Leaves are alternate, palmate and compound with serrate margins. Flowers are five petaled, white to light pink blooming in early summer. Fruit production is heavy and well favored by robins and other songbirds. There are other non-native blackberry species in Oregon. Armenian is the most robust.
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Basic Info: Atlantic ivy
Hedera hibernica
Designation: List B
Documents: Profile Distribution
Introduction: Very robust perennials, English and Atlantic ivies produce thick, woody, evergreen vines on trees with smaller long, trailing stems on forest floors. The leaves are alternate and waxy. Juvenile leaves are lobed, mature leaves larger and pointed with no lobes. When light and nutrients are optimum as in forest canopies, green or white flowers are produced forming black berries that are relished by starlings and robins, their main dispersal agents.
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Basic Info: Barbed goatgrass
Aegilops triuncialis
Designation: List A, List T
Documents: Profile Risk Assessment Distribution
Introduction: Barbed goatgrass is annual; grows 8 to 16 inches tall with few to many clumps. Leaf sheaths contain white hairs when young, becoming more or less smooth once matured. The blades are rigid, sharp, and spreading. Immature spikes are often reddish or purplish. Mature spikes are cylindrical and disperse from the parent plant as joined units at maturity, eventually breaking down to release their seeds. Grains are 1/4 inch long, resembling a wheat kernel.
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Basic Info: Biddy-biddy
Acaena novae-zelandiae
Designation: List B
Documents: Profile Distribution
Introduction: Biddy-biddy is low growing perennial forb stands only four to eight inches tall. Biddy-biddy spreads by stolons that root at the nodes creating dense vegetative mats in pastures and lawns. Leaves are alternate and finely dissected, with mature plants having 5 to 11 leaflets 1/4-2/3 inches long. Flower heads are spherical, and turn into a round bur that disperses as a unit when mature.
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Basic Info: Bohemian knotweed
Fallopia x bohemica
Designation: List B
Documents: None Available
Introduction: Bohemian knotweed is a hybrid between giant and Japanese knotweed and shares characters of both parent species. Plants are usually 6.5 to 10 feet tall, shorter in dry areas. Stems are stout, cane-like, hollow between the nodes, somewhat reddish-brown and usually branched. The plants die back above ground at the end of the growing season. The stem nodes are swollen and surrounded by thin papery sheaths. Leaves can be either spade or heart-shaped, usually more heart-shaped lower down on the stems and more spade-shaped near the branch ends. This variability in leaf shape is one identifying character since the parent species generally have either heart-shaped or spade-shaped leaves. The leaves are also intermediate in texture between the parent species - thicker and rougher than giant knotweed but less so than Japanese knotweed. On flowering stems, leaf tips are characteristically long and gradually tapered. One key identifying feature is the hairs on the leaf undersides, especially along the mid vein. Hybrid knotweed has hairs that are short, broad-based and triangular-shaped compared with long and wavy in giant knotweed and reduced to barely noticeable bumps in Japanese knotweed. These hairs are easiest to see with a hand lens during the spring and summer, often falling off later in the season. The flowers are small, creamy white to greenish white, and grow in showy plume like, branched clusters from leaf axils near the ends of the stems. Flower clusters are generally about the same length as the subtending leaf, unlike the shorter flower clusters found on giant knotweed and the longer clusters found on Japanese knotweed. Leaf and flower characters are most reliable when looking near the middle of a branch. The fruit is 3 sided, black and shiny.
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Basic Info: Buffalobur
Solanum rostratum
Designation: List B
Documents: Profile Distribution
Introduction: Buffalobur is a warm season annual growing two to three feet high. The stems, leaves, and even flowers sport an array of sharp spines. The leaves are deeply lobed growing up to 5 inches long. Yellow flowers emerge midsummer to September, are one inch in diameter and are formed by five fused petals. When mature the seedpod is a spine-covered dry berry covered contains numerous black, wrinkled and flattened seeds.
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Basic Info: Bull thistle
Cirsium vulgare
Designation: List B
Documents: Profile Distribution
Introduction: Bull thistle is a Eurasian native, widely established throughout North America. Accidental introductions have occurred many times through imported seeds and grains. Historically, the plant found limited application for medicinal uses and some parts were deemed edible.
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Basic Info: Butterfly bush
Buddleja davidii (B. variabilis)
Designation: List B
Documents: Profile Risk Assessment Distribution
Introduction: Butterfly bush is a perennial shrub growing up to 10” high. Leaves are narrow, opposite, green to blue-gray. Flowers are small, purple and heavily bunched in 8-10 inch flower spikes. Butterfly bush appears similar to lilac but blooms much later (late summer) than lilac.
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Basic Info: Camelthorn
Alhagi pseudalhag
Designation: List A
Documents: Profile Risk Assessment Distribution
Introduction: Camelthorn is a perennial and flowers from June to July. It grows from 1½ to 4 feet tall. Stems are greenish with slender spines ¼ to 1¾ inch long. Leaves are wedge-shaped, hairless on the upper surface, and ¼ to 1¼ inch long. Flowers are small, pea-like, pinkish purple to maroon, and occur on short, spine-tipped branches along the upper portion of the plant. Reddish-brown jointed seed pods are curved upward and deeply indented with each seed clearly outlined in the pod.
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Basic Info: Canada thistle
Cirsium arvense
Designation: List B
Documents: Profile Distribution
Introduction: Canada thistle is classified as a creeping perennial. Plants are either all male or all female. Its leaves are wavy, margined to lobed, up to 6 inches long and armed with yellowish spines. It has small purple to white flowers that are born in clusters. It sports an extensive horizontal-spreading root system enabling the plant to create dense patches. Fragmentation of the root system during tillage aids in dispersal throughout a field creating headaches for farmers. It has large seed production but a low percentage of viable seeds.
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Basic Info: Cape ivy
Delairea odorata
Designation: List A, List T
Documents: Profile Distribution
Introduction: Cape ivy is a perennial vine that climbs up trees and will reach heights of 16.4 ft. (5 m) in suitable climates. The leaves are alternate, broadly deltate to ivy-shaped with 5-7 shallow, but with sharply pointed lobes. Flowers are axillary or terminal cymes, with individual flowers yellow, disk corollas 0.16-0.2 in. (4-5 mm) long arranged in clusters.
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Basic Info: Coltsfoot
Tussilago farfara
Designation: List A
Documents: Profile Risk Assessment Distribution
Introduction: A perennial forb, coltsfoot grows 4 to 8 inches high sporting bright yellow, dandelion-like flowers that appear in early spring before the leaves emerge. It has white, fluffy seed heads. Large deep-green leaves develop later, often forming a dense canopy covering the soil. The top leaf surface has a smooth, almost waxy appearance; the underside covered with white wool-like hairs. Leaf stems and larger leaf veins are distinctly purple in color. It spreads by windblown seeds or by underground rhizomes, chopped and dispersed in agricultural fields by tillage equipment. Root fragments can produce dense patches of aboveground foliage ranging from 10 to 20 feet in diameter.
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Basic Info: Common bugloss
Anchusa officinalis
Designation: List B, List T
Documents: Brochure Profile Distribution
Introduction: A perennial herb, common bugloss flowers from May to October. It grows one to two feet tall. The stems and leaves are fleshy and coarsely hairy. Basal leaves are lance shaped while upper leaves are progressively smaller up the stem, stalkless and clasping. It has blue to purple flowers with white throats and five petals. The fiddleneck flower stem uncoils as each bud opens. Its fruit is a four-chambered nutlets and each nutlet contains one seed. One plant can produce an average of 900 seeds, which remain viable for several years. Common bugloss is similar to blueweed, Echium vulgare and can be easily confused. The taproot produces a purplish red dye.
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Basic Info: Common cordgrass
Spartina anglica
Designation: List A
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Cordgrasses are salt-tolerant perennial grasses, growing in estuaries worldwide. Common cordgrass grows 1 to 4 feet tall with flat leaf blades and margins, loosely in-rolled at tip. They are ¼ to ½ inch wide at base. Leaf blades project at a 40-80° angle to the stem. Stem Internodes are fleshy; inflorescence’s slightly open; branching loosely erect to ascending and loosely overlapping. Fleshy rhizomes are long making manual removal difficult. Common cordgrass has characteristics similar to other cordgrasses, therefore a detailed plant identification key is recommended for positive identification. Common cordgrass has not been identified in Oregon.
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Basic Info: Common crupina
Crupina vulgaris
Designation: List B
Documents: Profile Distribution
Introduction: A winter annual that flowers in June to July. It grows one to three feet tall. Leaves are alternate, with a coarse, rough texture when touched. Cotyledons (seed leaves) have a dark purple vein. Flower heads are narrow and topped with pink, lavender or purple flowers in groups of up to five. Seeds have a distinct ring of dark, stiff, bristles encircling broad end.
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Basic Info: Common frogbit
Hydrocharis morsus-ranae
Designation: List A
Documents: Profile Distribution
Introduction: Common frogbit or European frogbit is an herbaceous, annual (or short-lived perennial) that resembles a small water lily and can form large, dense colonies of floating plants with tangled roots. Plants have waxy, green heart or kidney-shaped leaves (1-6 cm (0.5-2.25 in) across) with purple undersides which attach to strong, flexible stolons. Frogbit plants produce small (1 cm across) showy, cup-shaped flowers that are held above the water on short peduncles; flowers are white in color with a yellow dot near the base of each petal. Frogbit produce turions, overwintering in the substrate later emerging in late spring. European frogbit forms dense mats through spreading stolons in still to slow-moving water; it is considered one of Canada’s leading invasive aquatic threats.
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Basic Info: Common reed
Phragmites australis
Designation: List B
Documents: Profile Risk Assessment Distribution
Introduction: Common reed is a large perennial grass species with creeping rhizomes and stolons, and terminal, plume-like flowering stalks. This plant has woody hollow stems that can grow 1 to 4 meters tall. Leaves are 15 to 40 cm long with an open leaf sheath. Phragmites grows in sites that hold shallow water, including roadside ditches, marshes, swamps, brackish estuaries, and alkaline wetlands. Reproduction is primarily vegetative, through an extensive network of rhizomes, which can grow horizontally up to 1.8 m per year depending on the climate. Stolons are produced in young stands or over open water, growing up to 11 cm per day, and further aid in rapid stand expansion and dispersal during storm events. Seeds are shed from November through January and are dispersed by wind, water, and animals. Once seeds germinate and become established, young plants persist for at least two years where they resemble many other grass species. When seedlings establish in inland or low salinity areas, the infestation will typically expand radially, resulting in distinct circular patches. Long distance seed dispersal is accomplished by water, wind, and wildlife.
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Basic Info: Creeping yellowcress
Rorippa sylvestris
Designation: List B
Documents: Profile Distribution
Introduction: Creeping yellow cress is a perennial forb growing up to 20 inches tall. Leaves are 2 to 4 inches long, pinnately divided into narrow, sharply toothed lobes. Flowers are yellow with four small, rounded, spatula-shaped petals displayed on branching stems in elongated clusters. Flowering occurs in June through August. Creeping yellow cress initially develops a taproot that later extend outward developing an extensive system of laterally creeping rhizomes. New shoots develop from these lateral roots. Rhizome fragments created by tillage develop into new plants spreading the infestation around the field. Fruit is a slender green pod up to ½ inch long, angled out and somewhat up from the stalk.
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Basic Info: Cutleaf teasel
Dipsacus laciniatus
Designation: List B
Documents: Profile Distribution
Introduction: Cutleaf teasel is a biennial forb growing up to seven feet tall supported by a large taproot. Flowers are small, white and packed into terminal heads enclosed by stiff, spiny bracts. Leaves on the flowering stalks are large, deeply lobed, opposite, and wrap around the stem forming small reservoirs holding water at their base. Both leaves and stems are prickly. Common teasel is similar, but has purple flowers and no lobes on upper leaves.
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Basic Info: Dalmatian toadflax
Linaria dalmatica
Designation: List B, List T
Documents: Profile Distribution
Introduction: This perennial grows two-three feet tall with thick water-conserving stems and leaves. It is very drought tolerant. The leaves are waxy, green, heart-shaped and one-three inches long. Flowers are one inch long and similar to snapdragons and very showy. Dispersal is both by seed and by creeping lateral roots.
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Basic Info: Delta arrowhead
Sagittaria platyphylla
Designation: List A, List T
Documents: Profile Risk Assessment Distribution
Introduction: Sagittaria platyphylla is a rhizomatous aquatic plant, thriving in many aquatic habitats. It forms extensive infestations in shallow waterways, where it can seriously restrict water flow, increase sedimentation and aggravate flooding. Infestations of Sagittaria platyphylla can also displace native plants in wetland areas. It is known to exist in only one wetland in Oregon, located in the Portland area. Though this population is still relatively small, it is demonstrating weedy tendencies within the confines of the marsh it inhabits. Worldwide, the species is most problematic in Australia and New Zealand where it invades wetlands, shallow ponds and is seriously impacting water movement through irrigation canals and drainage ditches.
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Basic Info: Dense flowered cord grass
Spartina densiflora
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Dense-flowered cordgrass is a perennial salt-tolerant aquatic grass that grows 1 to 5 feet tall. It has a distinct bunchgrass-like growth form. The leaf (blade) is tough, grayish in color and margins are in-rolled, narrow and long. Blades are at a 15-35 degree angle to the stem. The inflorescences are narrow, dense, and cylindrical with branches erect and overlapping. Unlike other spartina species, dense-flowered cordgrass reproduces only by seeds and thrives very well in rocky substrate.
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Basic Info: Diffuse knapweed
Centaurea diffusa
Designation: List B
Documents: Profile Distribution
Introduction: Diffuse knapweed is a biennial forb growing up to 3’ tall. It is single-stemmed sporting numerous lateral branches resulting in a bushy growth form. Flowers are white to rose, sometimes purplish, flowering from midsummer to fall. Flower heads are slender with pointed, fringed bracts growing out of urn-shaped heads. It reproduces by seed, dispersed by the tumbling of windblown plants or on the fur of animals. A single plant can produce approximately 18,000 seeds.
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Basic Info: Dodder
Cuscuta approximate, pentagona and indecora
Designation: List B
Documents: Profile Distribution
Introduction: Dodders are annual-sprouting parasitic plants. They flower from July to October. Stems are yellowish, thread-like and twining. Leaves are reduced to thread-like scales. Flowers are very small, white to pink, numerous, shallow-cupped, and grow in compact clusters. They are easily recognized by their thickly intertwining bright yellow to orange-yellow growth. Oregon breaks out smoothseed(Cuscuta approximate, Five-angled(Cuscuta pentagona) and Bigseed(Cuscuta indecora) on the noxious weed list.
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Basic Info: Dog rose
Rosa canina
Designation: List B
Documents: None AvailableRisk Assessment Distribution
Introduction: Dog Rose is Eurasian in origin and is highly invasive to dry rangelands in Oregon. Deciduous shrub, erect up to 8 feet, dense, large oval down curving thorns on stem. Sweetbriar and dog roses look very similar. They are both big brushy round shrubs and they both have nickel sized fruit. Sweetbriar rose has hairs on its sepals and underneath the leaves. Dog rose is not hairy or glandular at all. The leaves of sweetbriar rose have a sweet smell while dog rose leaves are not scented. Dog rose has pointier leaves and white flowers, while sweet briar rose has rounder leaves and pink flowers. Spreads mainly by dispersal of seed by birds. Can colonize and dominate rangelands, pastures and riparian areas.
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Basic Info: Dyer's woad
Isatis tinctoria
Designation: List B
Documents: Profile Distribution
Introduction: Dyer's woad grows up to three feet tall from a thick taproot that extends to five feet deep. Multiple stems arise from the base sporting foliage having a distinctive blue-green cast with whitish glaze. The upper leaves are smaller and clasp the stem with ear-like projections. Flowers are bright yellow, small and in highly visible clusters in the spring. Flowers have four spoon shaped petals. Fruit pods are flat and black or purplish brown. The most vigorous populations occur mainly in sandy, gravelly soils, and in marginal farmlands.
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Basic Info: English hawthorn
Crataegus monogyna Jacq
Designation: List B
Documents: Profile Risk Assessment Distribution
Introduction: English hawthorn is a broadly spreading shrub or small tree growing up to 25’ tall. The trunk has pale, gray smooth bark and younger stems bear sharp thorns making the plant useful for natural fence plantings in pastures. The leaves are 1-2 inches long and deeply lobed, sometimes almost to the midrib, with the lobes spreading out like a birds foot. Flowers are produced in showy white clumps from late spring to early summer in clumps of 5-25 blossoms; each flower is about 1 cm diameter. Pollinated flowers produce a haw, which is a small, oval, dark red fruit about 1 cm long, berry-like, but structurally a pome containing a single seed.
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Basic Info: English ivy
Hedera helix
Designation: List B
Documents: Profile Distribution
Introduction: Very robust perennials, English and Atlantic ivies produce thick, woody, evergreen vines on trees with smaller long, trailing stems on forest floors. The leaves are alternate and waxy. Juvenile leaves are lobed, mature leaves larger and pointed with no lobes. When light and nutrients are optimum as in forest canopies, green or white flowers are produced forming black berries that are relished by starlings and robins, their main dispersal agents.
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Basic Info: Eurasian watermilfoil
Myriophyllum spicatum
Designation: List B
Documents: Profile Distribution
Introduction: Eurasian watermilfoil is a perennial aquatic plant, rooted to the bottom and extending to the surface in shallow lakes and ponds. Purplish red-branching stems have feather-like leaves in whorls of four at each node. Male flowers are purplish while whitish flowers are female; all projecting above the water surface for pollination. The plant primarily reproduces through stem fragmentation.
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Basic Info: European water chestnut
Trapa natans
Designation: List A
Documents: Profile Risk Assessment Distribution
Introduction: Water chestnut is an annual aquatic plant forming dense mats on the surfaces of lakes, ponds and slow moving waters. The emerged leaves are diamond-shaped with toothed edges, arranged on inflated, spongy stalks and occur in clusters up to 20 inches across. Submersed leaves are long and narrow are often replaced with green feather-like structures. Flowers are small, solitary, white to light purple. Fruit is a large swollen nut with two to four sharp spines.
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Basic Info: False brome
Brachypodium sylvaticum
Designation: List B
Documents: Profile Risk Assessment Distribution
Introduction: This attractive perennial grass forms bunches of lime-green leaf blades. Leaf color is bright green throughout the growing season turning bleached white during the winter, a strong indicator of false brome. Leaf margins and lower stems are hairy with no red streaking on the stems. Flowers and seeds are spiked and droopy with no stalks. False brome appears to be self-fertile producing few to a couple hundred seeds per plant. Isolated plants are observed to produce viable seeds becoming new weed epicenters complicating control efforts. Seed movement is by wildlife with both birds and small mammals transporting seeds. Long-distance dispersal is predominantly through logging activities, roadside maintenance equipment and recreational activities within infested areas.
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Basic Info: Field bindweed
Convolvulus arvensis
Designation: List B
Documents: Profile Distribution
Introduction: Field bindweed is a deep-rooted herbaceous perennial. Its stems are prostrate, one to four feet long often climbing fences and shrubs or forming dense tangled mats. Leaves are alternate, arrowhead-shaped with lobes at the base. Flowers are bell or trumpet shaped, white to pinkish and one inch in diameter. Its fruit is a small, round capsule, usually four-seeded. It looks and grows similar to the ornamental morning glory.
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Basic Info: Flowering rush
Butomus umbellatus
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Flowering rush is a perennial water-loving plant in the Butomaceae family and not a true rush species. It is easy to identify when flowering, difficult when not. It’s a tall plant growing 1.5 meters or more, triangular in cross-section and topped by an umbel of showy-white or pink flowers that emerge in late summer to early fall. The flowers consist of three petal-like sepals with no real petals present. Flowering rush can grow either as an emergent in meter deep water or in the lower marsh, acquiring two distinct growth forms depending on environment. The emergent form has stiff narrow leaves growing rigid and upright. Flowering rush reproduces both asexually by rhizomes and bulblets and sexually through seed production. There are two genetic forms in North America, the most dominant being diploid. Seed production only occurs in diploids with greatly increased bulblet production as well. Triploids reproduce entirely by bulblets and rhizomes. Moving water is the predominant dispersal mechanism as well as human activities and wildlife feeding.
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Basic Info: French Broom
Genista monspessulana
Designation: List B
Documents: Profile Distribution
Introduction: French broom is a leafy perennial shrub growing three to ten feet tall. It is in the legume family. It is similar in appearance to scotch broom except plants do not grow as erect, leaves are larger, trifoliate, numerous and are retained the entire year. Its yellow flowers emerge April through June. They are smaller, but still distinctly pea-like.
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Basic Info: Garden yellow loosestrife
Lysimachia vulgaris
Designation: List A, List T
Documents: Profile Risk Assessment Distribution
Introduction: Garden loosestrife is an erect rhizomatous perennial growing to 1.2 m tall, with terminal panicles of showy yellow flowers. Lanceolate to ovate leaves (7-12 cm long, 1.5-4 cm wide) are opposite to whorled, sessile (or nearly so) and dotted with very small black to orange glands (DiTomaso and Healy 2003). The stems and abaxial leaf surfaces are hairy; stems are sometimes slightly flattened. Flowers have five ovate sepals with maroon margins (figure 2); the corolla is approximately 2.5 cm in diameter with five yellow petals (8-12 mm long) and sometimes with red or orange bases.
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Basic Info: Garlic mustard
Alliaria petiolata
Designation: List B, List T
Documents: Profile Risk Assessment Distribution
Introduction: Garlic mustard is a biennial. The rosettes form by midsummer the first year, overwinter, then bloom April through June the second year. It grows an average height of one to three feet tall. Basal leaves are dark green, kidney shaped, scalloped and two to four inches in diameter. Stem leaves are alternate, sharply toothed, triangular, and get smaller towards the top of the stem. Garlic mustard produces a distinct garlic odor when crushed. Flower stalks are usually single, branched or not branched. Flowers are ¼ inch wide with four white petals that are narrow at base. The plant is quite showy.
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Basic Info: Giant hogweed
Heracleum mantegazzianum
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Giant hogweed is a robust member of the carrot family (Apiaceae) noted for its huge leaves and an umbrella-like flower head. As a short-lived perennial, it frequently grows a stalk 10-15 feet tall splotched with reddish-purple blotches and pustules. The stalks are hollow with a three to four inch diameter; flower heads may attain a two to three foot diameter. Flowers generally develop in two to four years with bloom time occurring in May-July. Leaves are also impressive growing three to five feet wide, are compound and deeply incised. This plant closely resembles the common native cow parsnip which rarely exceeds six feet high sporting a flower head only 8-12 inches wide.
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Basic Info: Giant knotweed
Fallopia sachalinensis (Polygonum)
Designation: List B
Documents: Brochure Profile Distribution
Introduction: Giant knotweed is a robust perennial, growing annually from woody rhizomatous roots. It blooms from August through September. Rhizomes of giant knotweed often have a diameter of 3 inches and may spread to 65 feet laterally. The stems are generally clustered, erect, hollow, and grow up to 10-11 feet tall. Leaves are alternate, oval and large, frequently 12 inches long, with a cordate or heart-shaped base. Flowers are small, creamy white and packed in racemes producing an abundance of nectar, popular with pollinators. Giant knotweed has the ability to sprout from both aboveground nodes and rhizomes in the presence of adequate moisture. Humans spread the species through yard waste dumping, or using contaminated dirt and ornamental plantings. Flood events are the most important mechanism for transporting the plant in individual watersheds.
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Basic Info: Giant Reed
Arundo donax
Designation: List B
Documents: Profile Risk Assessment Distribution
Introduction: Arundo donax, a true giant in the grass family, often growing 20’ high, has devastated waterways throughout the southwestern United States. Originally planted widely for windbreaks, erosion control and an ornamental. Arundo is commercially grown in some parts of the world. Attempts to grow in the Columbia Basin as a biofuel replacement for the coal fired power plant in Boardman, OR did not prove to be economically viable; ODA is overseeing eradicated of all Arundo plants in this trial area in Morrow and Umatilla Counties.
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Basic Info: Goatsrue
Galega officinalis
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Goatsrue is a deep-rooted perennial legume, regrowing each year from a crown and taproot. Plants may have up to 20 hollow stems reaching 2 to 6 feet tall by late summer. The first seedling leaves are large, oval and dark green while mature leaves are alternate, odd-pinnate with 6 to 10 pairs of leaflets. The plant's stems and leaves contain a poisonous alkaloid, galegin, which renders the plant unpalatable to most livestock, and lethal in large quantities. The white and bluish to purplish pea-like blossoms are borne in terminal or axially racemes. Each blossom produces a straight, narrow, smooth pod, with 1 to 9 seeds per pod. A single plant may produce upwards of 15,000 pods. Goatsrue seeds are bean-shaped, dull yellow in color, and about 2 1/2 times the size of alfalfa seeds. Seeds drop on the ground when mature and may be spread by water, equipment, or animals. Seeds typically remain dormant until scarified and may remain viable for 10 years.
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Basic Info: Gorse
Ulex europaeus
Designation: List B, List T
Documents: Profile Distribution
Introduction: Gorse is a perennial, heavily armored evergreen shrub growing from 3 to over 10 feet tall. Gorse plants are shrubby with stout and erect spreading branches covered in terminal thorns frequently forming dense thickets. Clusters of yellow pea-like flowers can be found on the plant throughout the year but peak bloom occurs March through May. Seedpods are hairy ½ to ¾ inch long, and brown when ripe. Mature pods burst, scattering seeds for several feet.
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Basic Info: Hairy whitetop
Lepidium pubescens
Designation: List B
Documents: Profile Distribution
Introduction: Hairy whitetop is a perennial mustard, growing 1 to 1.5 feet tall. Leaves are three inches long and one inch wide, often smaller. Hairs sparse. Petals white, mostly two to three and tiny. Pods strongly inflated, spherical to ovoid, and covered with short hairs. Hairy whitetop can be difficult to distinguish from hoary cress in the vegetative state though the white hairs lend it a more silvery-grey color
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Basic Info: Halogeton
Halogeton glomeratus
Designation: List B
Documents: Profile Distribution
Introduction: Halogeton is a succulent summer annual growing a few inches to 1½ foot tall. The taproot can reach depths of 20 inches with lateral roots spreading 18 inches in all directions. Its main stems branch from the base, spreading horizontally at first then becoming erect. Plants are blue-green in spring and early summer, turning red or yellow later in the season. Leaves are small, fleshy, nearly tubular and tipped with a needle-like spine. Flowers are inconspicuous and borne in the leaf axils. Blooming period lasts from July to September. Halogeton is very prolific seeder producing as many as 75 seeds per inch of stem. Mature plants often break off, tumbling across the landscape, spreading seed as it rolls. Seed can survive ingestion by sheep and rabbits.
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Basic Info: Herb Robert
Geranium robertianum
Designation: List B
Documents: Profile Distribution
Introduction: Herb Robert is a branching, low growing winter and spring annual. Its light green leaves are deeply dissected and release a pungent odor making this plant easy to recognize. As the plants mature the foliage turns red. The stems are highly pubescent, have multiple forks, and are brittle at the joints. The roots are shallow allowing for easy hand removal. The pink flowers are five petaled. Herb Robert reproduces only by seeds. Flowers are usually self-fertile creating uniform populations. Seeds are matured in elongated pointed capsules that eject up to 20 feet when disturbed. Herb Robert tolerates a wide range of light intensities thriving best in open canopied forests or along the edges of forests. It can be highly competitive with native early spring forbs but less so against grasses. Often Herb Robert takes advantage of habitats that have been opened up through weed control activities such as English ivy or false brome removal.
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Basic Info: Himalayan knotweed
Polygonum polystachyum
Designation: List B
Documents: Profile Distribution
Introduction: Himalayan knotweed is a perennial polygonum growing up to 6 feet tall and is related to giant and Japanese knotweeds. Its leaves are alternate, long and narrow (4 to 8 inches), and tapered compared to Japanese and giant knotweeds that are ovate and heart shaped, respectively. It has branching inflorescences in an array of lacy clusters of many white small fragrant flowers. Stems are numerous, glabrous, ribbed, reddish-brown and erect. It blooms from late July to October.
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Basic Info: Hoary Alyssum
Berteroa incana
Designation: List A, List T
Documents: Profile Risk Assessment Distribution
Introduction: The plant has the general look of many of the mustards so it might go unnoticed without close examination. The whole plant except the flower is covered with fine hairs giving it a slight grey or hoary appearance. Four bright white, notched petals on clumps of flowers are clustered at the stem tips. Further, the plant has non-clasping stem leaves that have smooth edges.
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Basic Info: Hoary cress whitetop
Lepidium draba
Designation: List B
Documents: Profile Distribution
Introduction: Whitetop is a perennial mustard growing up to two feet tall from an extensive root system. Its lower leaves are blue-green and lance shaped and its upper leaves have two lobes clasping the stem. It produces many white flowers with four tiny petals, giving plant a white, flat-topped appearance. Three known species lens podded, globe podded, and heart podded whitetop are identified by different shaped seed pods. Whitetop plants die back to the roots in summer as the seeds mature.
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Basic Info: Houndstongue
Cynoglossum officinale
Designation: List B
Documents: Profile Distribution
Introduction: Houndstongue is a biennial growing from 1 to 4 feet tall. Rosettes form the first year later sending up a flowering stalk in the second. Leaves are alternate, rough, hairy, and 1 to 12 inches long. Flowers are reddish purple and terminal. It reproduces only from seed with each plant capable of producing up to 2,000 seeds. Houndstongue prefers well-drained, relatively sandy and gravelly soils in habitats comprised of shady areas under the canopy of forests, in native grasslands, in pastures, meadows, along roadsides, and in disturbed sites.
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Basic Info: Hydrilla
Hydrilla verticillata
Designation: List A
Documents: Brochure Profile Distribution
Introduction: Hydrilla is one of the most serious biological threats to aquatic ecosystems in temperate climate zones. Dense stands of hydrilla provide decrease habitat for fish and other wildlife altering water quality by raising pH, decreasing oxygen, and increasing temperature. Dense weed mats create stagnant water providing breeding grounds for mosquitoes. Hydrilla interferes with recreational activities such as swimming, boating, fishing, and water skiing and will clog irrigation ditches and intake pipes. Control programs are expensive and the effects often short-lived.
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Basic Info: Iberian starthistle
Centaurea iberica
Designation: List A, List T
Documents: Brochure Profile Distribution
Introduction: Iberian starthistle is actually a heavily armored knapweed species and not classified as a true thistle. It can function as an annual or biennial depending on moisture conditions. Seedlings will sprout in the fall or early spring forming spiny rosettes in May and June. Blooming continues from midsummer through fall as the plant grows 1 to 6 feet tall. To conserve moisture the plant is covered in fine hairs, with narrow linear leaves retarding moisture loss. Flower heads are purple and arrayed with straw-colored spine-like bracts over 1 inch in length. Seeds are plumed, the distinguishing factor between this plant and purple starthistle.
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Basic Info: Indigo bush
Amorpha fruticosa
Designation: List B
Documents: Profile Distribution
Introduction: It is a deciduous perennial shrub native to the Great Plains. Indigo bush grows up to 13 feet high with a width that is typically twice its height. The older branches are woody; young twigs are green and hairy. Leaves have 13 to 25 leaflets each and are 1 to 2 inches long, dotted and hairy. Flowers are showy-lavender colored, densely arranged in erect racemes each with a single petal and yellow anthers. The fruit is a small, straight to curved pod with one to two seeds within. Pods remain buoyant for over a week in water. A legume, it produces its own nitrogen giving it an advantage in low nitrogen environments such as gravel bars.
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Basic Info: Italian thistle
Carduus pycnocephalus
Designation: List B
Documents: Profile Distribution
Introduction: Annual or sometimes biennial, blooming May to June. It grows 1 to 4 feet tall. Stems have spiny wings. The leaves are deeply cut into 2 to 5 pairs of lobes, with white variegation and a undersurface that is slightly woolly. Flowers are purplish to pinkish, borne in cylindrical heads either solitary or in clusters of more than 5. Flower bracts are hairy. Fruits from outer part of flower head are gray in color and inner portion are yellowish to tan.
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Basic Info: Japanese dodder
Cuscuta japonica
Designation: List A
Documents: Profile Distribution
Introduction: Japanese dodder is an aggressive parasitic vine possessing no chlorophyll; it receives its energy from its host plant. The leafless vines are showy with vibrant yellow-green or gold coloration. It has robust, spaghetti-like stems in sharp contrast to all other native and introduced dodder species in North America which are low-growing and more thread or string-like. Infestations are often large, spreading, covering and killing large shrubs and trees. In contrast, infestations of other dodder species are likely to be smaller, infecting non-woody plants or small shrubs. In cooler climates plants die back in the winter but in warm regions, the species grows almost year-round.
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Basic Info: Japanese knotweed
Fallopia japonica (Polygonum)
Designation: List B
Documents: Brochure Profile Distribution
Introduction: Japanese knotweed is a deciduous perennial growing up to 9 foot tall. Annually growing from deep-rooted creeping rhizomes, it forms extensive clonal patches that are expensive to treat or remove. Stout hollow stems are greenish red, with nodes. Leaves are short stalked, 6 to 8 inches long by 4 to 5 inches wide. Japanese knotweed flowers are greenish-white to cream in large plume-like clusters at the ends of the stems. Bloom time occurs late July, to October. It establishes most often along riparian areas, though many reports place them in forest understories, forest edges, yards and gravel operations.
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Basic Info: Johnsongrass
Sorghum halepense
Designation: List B
Documents: Profile Distribution
Introduction: Johnsongrass is a perennial grass that grows three to six feet tall. Leaf blades are flat with a prominent white midvein. The stems are solid with prominent, swollen nodes. Flowers or spikelets are in pairs at the lower end of the flowering stalk, and in threes at the upper end. Johnsongrass has fibrous roots and extensive, thick creeping rhizomes. It grows in dense clumps or nearly solid stands competing with crops for light, water and nutrients. It reproduces by both seeds and rhizomes. A large single plant may produce hundreds to over a thousand seeds per year.
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Basic Info: Jointed goatgrass
Aegilops cylindrica
Designation: List B
Documents: Profile Distribution
Introduction: Jointed goatgrass is a winter annual growing to around 2.5 feet tall. The leaves have a number of visible hairs growing along the edge of the leaf and the foliage is a deep blue-green color. Seed heads (spikes) are cylindrical and narrow and break into individual segments at maturity during the summer months. The spike is made up of a number of spikelets, also called joints. Each joint is about an inch long and contains from one to three seeds that are generally viable for 3 to 5 years.
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Basic Info: Jubata grass
Cortaderia jubata
Designation: List B
Documents: Profile Distribution
Introduction: Jubata grass is a perennial grass ranging 6 to 10 feet tall. Plants have long leaves arising from a tufted base or tussock. The flower cluster is a plumed panicle at the end of a very long stem. Stems generally are at least twice as long as the tussock. Plumes consist of hairy female flowers, deep violet when immature, turning pinkish or tawny cream-white at maturity. Jubata grass is easily confused with pampas grass, Cortaderia selloana. The two species are distinguished by stem height, leaf, plume, and spikelet color, florets, leaf tip, and presence of viable seed. The tussocks of jubata grass are less erect and more spreading and not fountain-like, when compared to tussocks of pampas grass.
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Basic Info: King devil hawkweed
Pilosella piloselloides (Hieracium)
Designation: List A
Documents: Profile Distribution
Introduction: King-devil hawkweed is another one of the invasive perennial hawkweeds. This robust species grows 10 to 36 inches high, taller than other similar species. Leaves are hairy, spatula shaped and almost exclusively basal. Flower heads are clustered, yellow, 1/2 wide, and number up to 30 per plant. Flowering occurs during June to July in lower elevations. Dense hawkweed mats form through extensive stolon formation and seed germination. Allelopathy may also play a factor in curbing plant competition.
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Basic Info: Kochia
Kochia scoparia
Designation: List B
Documents: Profile Distribution
Introduction: Kochia is a fast-growing annual supported by a deep taproot and will grow up to six feet tall. Stems are many branched, round, slender and often red-tinged late in the season. Leaves ½ to two inches long, alternate, flat, lance-shaped with margins fringed with hairs. Flower heads are green, petal-less, inconspicuous spikes in the axils of upper leaves. It blooms from July to October. Kochia has been used in Chinese and Korean folk medicine as treatment of skin diseases, diabetes, mellitus, rheumatoid arthritis, liver disorders, and jaundice.
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Basic Info: Kudzu
Pueraria lobata
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: This aggressive high-climbing vine often completely covers trees, shrubs and man-made structure forming “kudzu sculptures”. Vines may extend thirty to one hundred feet with stems ranging from one half to four inches in diameter. Up to thirty vines may grow from a single root crown. The deciduous leaves are alternate, six to eight inches long, have fuzzy leaflets three to four inches long, oval, lobed or nearly heart shaped. Purple to red colored pea-like flowers appear in mid-summer, form large hanging clusters, and have a pleasant grape-like odor. Fruit are dark brown flattened pods born in clusters, very hairy and ripening in the fall. Young stems are velvety covered in brown hairs, older stems and vines turn brown and smooth eventually forming a fine scaly bark. The roots form a fleshy taproot often seven inches or more in diameter, six feet or more in length and weighing as much as four hundred pounds.
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Basic Info: Leafy spurge
Euphorbia esula
Designation: List B, List T
Documents: Profile Distribution
Introduction: Leafy spurge is a deep-rooted perennial ranging in height from 6 inches to 36 inches. Its greenish-yellow inflorescences are borne in an umbel pattern, and it typically blooms from May to October. Each umbel supports seven to 10 groups of tiny, inconspicuous flowers, subtended by four crescent-shaped glands and two conspicuous greenish-yellow bracts. The bluish-green leaves of leafy spurge are usually alternate except for those located immediately under the inflorescence. These are in a whorled arrangement. Another characteristic is the two kinds of leaves present on the stem. Leafy spurge has milky white sap that will flow from any part of the plant following injury. This sap may cause severe irritation to human skin and is reported to cause blistering and hair loss on the legs of horses in heavily infested pastures.
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Basic Info: Lens podded whitetop
Cardaria chalapensis
Designation: List B
Documents: Profile Distribution
Introduction: Lens podded whitetop is a single-stemmed, erect perennial herb that grows less than knee high. The flowers are generally dense, white and typically flat-topped and the leaves are lance-shaped, up to four inches long and one inch wide and have a heart shaped base that clasps the stem. The seed pods are rounded in outline and nearly flat when mature. An infestation of this species is distinguishable by large white patches in fields.
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Basic Info: Lesser celandine
Ranunculus ficaria
Designation: List B
Documents: Brochure Profile Distribution
Introduction: Lesser celandine is an herbaceous, perennial plant in the buttercup family. It has a basal rosette of dark green, shiny, stalked leaves that are kidney to heart-shaped. It flowers from March to April, has eight glossy, butter-yellow petals, and is borne singly on delicate stalks that rise above the leaves. Pale-colored bulblets are produced along the stems of the above ground portions of the plant, but are not apparent until late in the flowering period. When in bloom, large infestations of appear as a green carpet with yellow dots, spreading across the forest floor. There are many varieties of lesser celandine including a double-flowered form with many crowded petals and dark green leaves mottled with silvery markings. The primary reproductive method is the formation of turions that are produced on the roots in large numbers. They are easily moved in contaminated dirt or by water. It prefers shaded to partially shaded sites though it can thrive in full sun with adequate soil moisture. Deciduous woods are an excellent habitat for this species enabling the plant to grow and bloom well before leaf initiation in the forest canopy.
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Basic Info: Matgrass
Nardus stricta
Designation: List A, List T
Documents: Profile Risk Assessment Distribution
Introduction: Matgrass is a slow growing perennial bunchgrass that is densely tufted and long-lived. It produces unbranched flower-spikes that carry the single-flowered spikelets along one side. Leaves are hard and bristle-like, bluish- green and up to 1/4 inch wide, appearing narrower because blades are tightly folded along the mid-rib. Stems are tipped by inconspicuous spikes that bear all spikelets on one side of the stems and grow up to eight inches tall. This grass is tightly rooted therefore hard to remove.
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Basic Info: Meadow hawkweed
Hieracium pratense
Designation: List B, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Meadow hawkweed is a creeping perennial with shallow, fibrous roots and long rhizomes. Basal leaves are hairy on both sides and lie flat to the ground, overlapping and smothering other plants. It stems and leaves exude milky juice when broken. The stems are bristly and usually leafless, although occasionally a small leaf appears near the midpoint. Stem height can reach to three feet tall and bear up to 30 half-inch diameter flower heads. Flowers are yellow and appear in May to July depending on elevation. After maturing, the shiny, black, plumed seeds are dispersed by wind, on clothing, hair, feathers, and vehicles.
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Basic Info: Meadow knapweed
Centaurea pratensis
Designation: List B
Documents: Profile
Introduction: Meadow knapweed is a hybrid of black and brown knapweeds. It blooms in midsummer to fall growing from robust root crown. Plant height generally reaches three inches. The lower leaves are long-stalked, upper leaves having no stalk. Stems are heavily branched and tipped by a solitary flower head up to one inch wide. Flower heads are pink to reddish purple, oval or almost globe shaped. A key identifying feature is the brown brushy, fringed bracts on the flower head. Meadow knapweed’s tough perennial root system makes manual control methods very difficult.
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Basic Info: Mediterranean sage
Salvia aethiopis
Designation: List B
Documents: Profile Distribution
Introduction: Mediterranean sage is a biennial growing generally two feet tall. First year growth consists of a large grayish rosette supported by a stout taproot. The leaves are very pungent when crushed. Flowers are mint-like, ½ to 1 inch long, yellowish-white, forming woolly clusters in a profusely branched arrangement, resembling a candelabra. Bloom time ranges from June to July. It is a prolific seed producer dispersing them similar to a tumbleweed across rangeland in late summer and fall.
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Basic Info: Meduasahead rye
Taeniatherum canput-medusae
Designation: List B
Documents: Profile Distribution
Introduction: Medusahead rye is a slender annual grass growing six to 18 inches tall. Seeds are housed in spikelets in a densely crowded bristly spike one to two inches long. Spikelets have tiny recurved barbs. Growth and seed production are early utilizing most surface moisture before native grasses begin their growth. Medusahead rye’s leaf blades are somewhat rolled, 1/16” wide. It is usually found in clay soils and has a shallow root system.
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Basic Info: Milk thistle
Silybum marianum
Designation: List B
Documents: Profile Distribution
Introduction: Milk thistle is a biennial or winter annual blooming from April through July. It grows two to six feet tall. Stems are stout, rigid and generally branching. Leaves are very broad and clasp the flower stem. The spiny margins and white marbling along veins are very distinctive. Flower heads are reddish-purple, spine-tipped and 3-4 inches across. The seed is capable of remaining dormant in the soil for many years.
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Basic Info: Mouse-ear hawkweed
Pilosella pilosella (Hieracium)
Designation: List A, List T
Documents: Profile Risk Assessment Distribution
Introduction: Mouse-ear hawkweed is a low growing perennial hawkweed with distinctive fuzzy leaves showing white midveins. It spreads with stolons like strawberry plants and has a fibrous root system. Yellowish-white flowers are produced on short, leafless stalks that are covered with stiff dark hairs. The flowers resemble those of dandelions. This may explain why the plant is easily overlooked. It prefers to grow in open grassy areas and does not tolerate shade.
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Basic Info: Musk thistle
Cardus nutans
Designation: List B
Documents: Profile Distribution
Introduction: Musk thistle is a biennial thistle with the characteristic formation of a rosette in the first year followed by a three to five feet tall flower stalk in the second. It blooms in early June. Flower heads are large, purple, solitary and usually nodding. Musk thistle has dark green leaves with light green midrib and wavy, spiny lobed margins. Leaves have a smooth waxy surface and appear winged at the attachment to the stem.
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Basic Info: Mytle spurge
Euphorbia myrsinities
Designation: List B
Documents: Profile Distribution
Introduction: Perennial; blooms in early spring. Grows 4 to 6 inches tall. Leaves alternately arranged in close spirals around the fleshy, trailing, blue-green stems. Flowers inconspicuous and surrounded by a showy yellow green bract. This plant prefers well-drained, dry to moist soils in partial shade to full sun. Myrtle spurge is an escaped ornamental inhabiting disrupted areas and non-crop areas. It grows well in zones 5-9 and is known to like dry rocky areas as well.
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Basic Info: Oblong spurge
Euphorbia oblongata
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Oblong spurge is a showy Euphorbia species that has become weedy in California and to a lesser degree in Oregon. As a perennial herb it produces up to 20 stems on a woody rootstalk, attaining nearly three feet of growth, then dying back in the winter. Leaves are alternate, smooth and hairless with finely toothed margins. All plant parts exude a caustic milky sap when cut, therefore, skin contact should be avoided. Numerous bright yellowish-green bracts are produced enclosing tiny flowers at terminal tips. Seedpods have a waxy appearance, and when mature, ripened pods forcefully eject their seeds for localized dispersal.
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Basic Info: Old man's beard
Clematis vitalba
Designation: List B
Documents: Profile Distribution
Introduction: Old man’s beard is a perennial, woody deciduous vine often growing up to thirty yards long. The leaves are opposite and compound, usually with five leaflets. Flowers are small, greenish white and found in clusters in the upper leaf axils. The characteristic feathery seed heads give this climber its name. Vines root with sustained ground contact creating dense horizontal growth in riparian forests.
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Basic Info: Orange hawkweed
Pilosella aurantiacum (Hieracium)
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Orange hawkweed is an aggressive perennial hawkweed sporting attractive, showy orange flowers. The bright orange flowers attract gardeners who are unaware of its aggressive nature. It rapidly spreads through lawns, flowerbeds and meadows through abundant seed production and aboveground runners (stolons) that root at the tips creating dense populations. The flower stalks grow up to 12+ inches tall and contain a milky sap. The vibrant orange-red flowers are clustered at the top of leafless stems. The stems are entirely covered by stiff, black, glandular hairs. Leaves are hairy, lance shaped, up to five inches long, and exclusively basal.
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Basic Info: Ovate goatgrass
Aegilops ovata
Designation: List A
Documents: Profile Distribution
Introduction: Ovate goatgrass is a winter annual; flowers May to July. Grows 10 inches tall. Similar to barbed and jointed goatgrass except spikes are ovate-cylindric disperse as units at maturity and do not break apart into joints.
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Basic Info: Parrots Feather
Myriophyllum aquaticum
Designation: List B
Documents: Profile Distribution
Introduction: Parrots feather is an attractive aquatic plant with feathery lime-green leaves arranged in whorls on long floating stems (rhizomes). Flowers are small and white. The emerged parts of the plants are a distinctive trait resembling small fir trees growing up to a foot above the water. Parrots feather is found in freshwater lakes, ponds, streams, and canals thriving in high nutrient environments. It tends to colonize slow moving or still water rather than in areas with higher flow rates. The emergent stems can survive on wet banks of rivers and lakeshores, so it is well adapted to moderate water level fluctuations.
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Basic Info: Paterson's curse
Echium plantagineum
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Paterson’s curse is an erect annual (less often biennial) in the Borage plant family. Plants can be single-stemmed or multi-branched with an abundance of stout hairs on stems and leaves. Flowers are most often blue-purple in color, but may be pink or white. Flowers are borne on fiddleneck or scorpioid-like inflorescences. Two of the five stamens in the flower are longer and project significantly from the joined corolla. In Oregon, blooming starts as early as March and continues through June. Reproduction and spread is by seed. Each flower produces four brown or gray nutlet seeds surrounded by a husk covered in bristles giving them a fuzzy appearance. Seeds are spread by vehicles, farm implements, humans, animal, water, wind, hay, and as a contaminant of commercial seed. Paterson’s curse seed has been found in wildflower mixes in Oregon.
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Basic Info: Perennial peavine
Lathyrus latifolius
Designation: List B
Documents: Profile Distribution
Introduction: Annual growth emerges from perennial roots each spring to a length of 2 to 7 feet. Stems are broadly winged with long, well developed tendrils. Pea-like flowers are an inch long and can be white, red or pink. Leaflets are well-developed stipules that are 1-2 inches long. Growth becomes very dense often completely covering all other low-growing vegetation. Vines are often found growing up into trees and shrubs. Seeds are brown colored, produced in pods and are ⅔ smaller than the common edible garden pea. This plant occupies a wide range of climactic conditions thriving in the warm wet environment of the Pacific Northwest to the cold dry conditions of the Rocky Mountain States. Little information has been published on this species and it is often overlooked as an invader. Though not listed in many western states as noxious, Idaho and Wyoming are now including it into their control plans as additional infestations appear.
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Basic Info: Perennial pepperweed
Lepidium latifolium
Designation: List B, List T
Documents: Profile Distribution
Introduction: Perennial pepperweed is an erect, semi-woody perennial forb growing from one to six feet tall. Basal leaves are larger than upper leaves, lance shaped, bright green to gray green, entire to toothed. Flowers are white, very small, and form dense clusters near the ends of branches. They produce a distinctive odor. Populations form dense monocultures, rapidly expanding from root fragments and seed.
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Basic Info: Pheasant's eye
Adonis aestivalis
Designation: List B
Documents: Profile Distribution
Introduction: Pheasant’s eye is a herbaceous annual with erect one-foot tall stems terminated with solitary, red-orange and black cup-like flowers. Bloom-time is in mid summer. The fern-like leaves are simple and alternate with blades two to three times pinnately dissected into linear segments. It prefers moist, well-drained soils but is adapted to seasonally dry soils also. Populations can be highly variable from year-to-year.
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Basic Info: Pine echium
Echium pininana
Designation: List B
Documents: None AvailableRisk Assessment Distribution
Introduction: It is a biennial or triennial, typically exists as a vegetative rosette for two three years, flowers once, and then dies. It produces a single, massive spire of light blue to purple flowers reaching approximately 15 feet in height and prized by garden enthusiasts for its unique leaves, shape, and flowering stalk. Leaves are mostly broadly lanceolate, and covered with flattened, soft to bristly. E. pininana’s main mode of reproduction is by copious seed production, in excess of 200,000 per plant which germinate readily resulting in dense carpets of seedlings. Habitat: E. pininana is native to the Canary Islands where it grows on the stony hill sides and laurel forests and tall heath shrublands at low elevations. In its native range, E. pininana is an endangered species through loss of habitat to agriculture. It has naturalized in some mild coastal areas of Ireland and California. It has escaped cultivation as an ornamental in some coastal areas Impacts: Potential economic impact from managing invaded coastal scrub, borders of marshes, woodlands, drainages roadways, natural coastal drainages and waste areas. Ecological Impacts include escaping from gardens or areas where it was dumped as garden waste. E. pininana has the potential to aggressively colonize creating a dense carpet of seedlings dominating vegetation in natural areas. Distribution: There are sites in Coos County-North Bend, Curry County. As of January 2022, no E. pininana populations have been detected or reported north of Coos Bay. This plant is just becoming an EDRR concern so sites could be increasing.
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Basic Info: Plumeless thistle
Carduus acanthoides
Designation: List A, List T
Documents: Brochure Profile Distribution
Introduction: Plumeless thistle can grow either as a winter annual or a biennial. One to four foot tall stems are covered with spiny wings for their whole length. It is similar in appearance to musk thistle but with smaller flowers and the winged stems. Rosette leaves are 4 to 8 inches long, stem leaves are alternate and blend into the stem. Flower heads in clusters of 2 to 5 and usually purple but can be yellow or white. Flowering season lasts May through July.
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Basic Info: Poison hemlock
Conium maculatum
Designation: List B
Documents: Profile Distribution
Introduction: Poison hemlock is a biennial member of the carrot family, growing from 3 to 7 feet tall on a deep taproot. Hollow stems are erect with leaves that are alternate, one per node, petioled, and pinnately divided. Flowers are white in compound stemmed umbels, much like little umbrellas. Poison hemlock reproduces only by seeds; dispersed by water, wind, on animal fur, human clothing, boots, and machinery.
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Basic Info: Policeman's helmet
Impatiens glandulifera
Designation: List B
Documents: Profile Distribution
Introduction: Policeman’s helmet is an herbaceous succulent annual, smooth stemmed, and hairless. The plants can grow to 8 feet tall when supported by blackberries, though most will be smaller. The leaf arrangement can be opposite or whorled with three leaves per node. Leaf shape varies from oblong to egg-shaped, with serrated edges. Flowers are solitary, irregular, ranging from white to all shades of pink, with 5 petals (2 fused) and 3 sepals (2 fused) and five fused stamens. The flower shape resembles an English policeman’s helmet. The seed capsules are elongated and when disturbed, explode, ejecting up to 800 seeds a short distance.
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Basic Info: Portuguese broom
Cytisus striatus
Designation: List B, List T
Documents: Profile Distribution
Introduction: Portuguese broom is a perennial leguminous shrub growing up to 10 feet tall. It’s appearance is similar to scotch broom except the pods are completely hairy, giving them the appearance of being pussy willow buds. The stems are more silvery compared to scotch broom, and the flowers are a more pale yellow color. The bark has a distinct vertical striated appearance.
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Basic Info: Puncturevine
Tribulus terrestris
Designation: List B
Documents: Profile Distribution
Introduction: Puncturevine is a warm-season annual growing completely prostrate to the ground. Single plants form dense mats four to six feet across. Leaves are opposite, hairy, divided into 4 to 8 pairs of leaflets, each about ½ in long. Flowers are small, yellow, ½ inch wide with five petals, borne in the leaf axil. Fruits, consist of a woody bur divided into 5 sections, breaking apart when mature into tack-like structures sporting sharp, rigid spines. A single plant can produce around 400 fruit each containing two or three seeds.
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Basic Info: Purple loosestrife
Lythrum salicaria
Designation: List B
Documents: Profile Distribution
Introduction: Purple loosestrife is a perennial aquatic invader growing up to seven feet tall supported by a large rhizomatous root mass. Growing as an upright bushy plant, it becomes adorned with spikes of purple flowers providing an abundance of nectar for honeybees. Flower color ranges from pink to purple, each flower possessing 5-6 petals and arrayed densely on a long spike. The seeds are tiny, dust-like, moved by water and birds. This former ornamental species can be found along wetlands, stream banks, and shorelines of shallow ponds.
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Basic Info: Purple nutsedge
Cyperus rotundus
Designation: List A
Documents: Profile Risk Assessment Distribution
Introduction: Purple nutsedge is considered one of the world's top 10 agricultural weeds. It thrives in moist conditions, most notably in the sandy soils found on river bottoms and mostly areas that are critical for food production in many third world countries. As a nutsedge, it forms nut-like turions that resist herbicide treatments and tillage. In infested countries, it is commonly found in turf, ornamental areas, cultivated fields and ditch banks. In Oregon, it is considered a potential threat to containerized horticultural products.
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Basic Info: Purple starthistle
Centaurea calcitrapa
Designation: List A, List T
Documents: Brochure Profile Distribution
Introduction: Purple starthistle is actually a heavily armored knapweed species and not classified as a true thistle. It can function as an annual or biennial depending on moisture conditions. Seedlings will sprout in the fall or early spring forming spiny rosettes in May and June. Blooming continues from midsummer through fall as the plant grows 1 to 6 feet tall. To conserve moisture the plant is covered in fine hairs, with narrow linear leaves retarding moisture loss. Flower heads are purple and arrayed with straw-colored spine-like bracts over 1 inch in length. Seeds are not plumed, the distinguishing factor between this plant and Iberian starthistle.
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Basic Info: Ragweed
Ambrosia artemisifolia
Designation: List B
Documents: Profile Distribution
Introduction: Common ragweed is an annual broadleaved weed and a member of the composite or daisy family. It has a shallow, fibrous root system and grows 2 to 4 feet high. Its stems vary from unbranched to bushy. Stems may be hairless, but usually they are densely covered with stiff erect hairs about 1/8 inch long. Mature leaves are 6 to 12 inches long and 4 to 6 inches wide and are deeply indented. On the second and subsequent leaf pairs, the veins are visible as depressions on the upper surface and as ridges on the lower surface.
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Basic Info: Ravenna grass
Saccharum ravennae
Designation: List A, List T
Documents: Profile Distribution
Introduction: Ravenna grass is easy to tell from most other grasses due to its size, it is similar to two other large perennial bunchgrasses that also have been used as ornamentals. Ravenna grass can be distinguished by having leaf blade bases that are very densely covered with fuzzy hairs that typically hide the ligule and the upper surface of the blade base. There are rarely hairs on the leaves of Pampas or Jubata grass. Ravenna grass can also be distinguished from the other two species because they both have sharply serrated leaves that can cut hands, while Ravenna is weakly serrated and doesn’t cut. Ravenna grass has very tall plumes on jointed stems that stand well above the larger basal leaves. These flowering stems have leaves up to the base of the inflorescence. Ravenna grass can have a red coloring on its stems. Jubata and pampas grass don’t have red on the stems.
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Basic Info: Ribbongrass
Phalaris arundinacea var. Picta
Designation: List B, List T
Documents: Profile Distribution
Introduction: It is a small to medium sized perennial ornamental grass or tall non-traditional groundcover. It grows to 1' tall in full sun, 1.5' tall in partial sun, and up to 3' tall in partial shade, spreading continuously at its perimeter to form a dense groundcover procumbent mat. Clumps have slow to medium growth rates at their perimeter. The best growth performance occurs in moist, well-drained soils in partial sun, but it is very tolerant of poor soils. Leaves are ¾ to 1 inch wide and 5 to 7 inches long. Lanceolate to narrow ovate leaves emerge briefly with pink and white variegation, but quickly change to longitudinal stripes (or ribbons) of green and white variegation as they expand (hence the common names of Garden's Garters, resembling striped garters or suspenders). Flowers are rare or sparse, white to pink and display in June and July, on a 2' stalk. Plants bleach to beige with the first frosts. Foliage remains attractive in winter.
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Basic Info: Rush skeletonweed
Chondrilla juncea
Designation: List B, List T
Documents: Profile Distribution
Introduction: Rush skeletonweed is a deep-rooted perennial with tough, wiry, latex-filled stems. It grows 1 to 4 feet tall. Bloom time occurs July to September. It is identified by coarse, downward pointed hairs on the lower 4 to 6 inches of the stems. The stems have almost no leaves. The flowers are yellow, 3/4 inch in diameter with 7 to 15 petals. It spreads primarily by seed, but roots scattered by cultivation can aid in dispersal.
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Basic Info: Russian knapweed
Acroptilon repens
Designation: List B
Documents: Profile Distribution
Introduction: Russian knapweed is a deep-rooted, long-lived perennial growing up to 2.5 feet tall. It forms dense colonies of erect branched stems sporting leaves covered in fine whitish hairs giving them a gray-green hue. Lower leaves are deeply lobed, 2 to 4 inches long; upper leaves are entire. It has cone-shaped flowering heads, ¼ to ½ inch wide, pink to lavender, growing at each branch tip. Flower bracts are rounded with papery margins. Roots are distinguishable by their black color and bark-like texture. Russian knapweed commonly grows along roadsides, pastures, croplands, irrigation ditches as well as riverbanks and disturbed areas. It prefers clay soils and a semi-arid environment.
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Basic Info: Saltcedar
Tamarix ramosissima
Designation: List B, List T
Documents: Profile Distribution
Introduction: Saltcedar species are spreading shrubs or small trees, 5-20 feet tall, with numerous slender branches and small, alternate, scale-like leaves. The pale pink to white flowers are small, perfect and regular, arranged in spike-like racemes. The distinct petals and sepals occur in fours or fives. The fruit is a capsule.
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Basic Info: Saltmeadow cordgrass
Spartina patens
Designation: List A, List T
Documents: Brochure Profile Distribution
Introduction: Saltmeadow cordgrass is a rhizomatous perennial grass 1 to 4 feet tall with very narrow leaf blades 0.5 to 2 mm wide. The leaves and flowering stems are deciduous being replaced each year. Leaf color is light green, often in contrast to the colors of native tufted hairgrass and sedges. The dark-colored flowering panicles are not taller than the leaves. Infestations grow slowly outward forming patches easily spotted from the air. Reproduction occurs by the release of root fragments during storm events or by seeding. Saltmeadow cordgrass is similar to common cordgrass (S. anglica), smooth cordgrass (S. alterniflora), and dense-flowered cordgrass (S. densiflora). A detailed key is recommended for positive identification.
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Basic Info: Scotch broom
Cytisus scoparius
Designation: List B
Documents: Profile Distribution
Introduction: Scotch broom is an attractive evergreen shrub with many slender, erect, dark-green branches. It can grow up to 8 feet tall. In May it is adorned with a profusion of yellow flowers maturing to flattened pods with up to a dozen seeds each. Mature dried pods will crackle and pop in mid summer ejecting the seeds a short distance. It can be confused with the less common Spanish broom, Spanish broom has fewer round stems, very few leaves, and larger yellow flowers.
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Basic Info: Scotch thistle
Onopordum acanthium
Designation: List B
Documents: Profile Distribution
Introduction: It is a robust biennial, sometime acting like an annual. It generally produces a rosette the first year and is capable of reaching heights up to 8 feet in the second. Winged stems support large leaves covered in fine soft white hair on upper leaf surface. Purple flowers are large producing large numbers of seeds. Thick stands often occur that are practically impenetrable because of the spiny nature and plant large size. Thistle patches are biennial producing dense growth one year and only a few plants the next, only to repeat the process the next year. It spreads only by seed.
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Basic Info: Shiny leaf geranium
Geranium lucidum
Designation: List B
Documents: Profile Distribution
Introduction: Shiny geranium grows predominantly as an annual weed though it may become biennial depending on moisture conditions. Stems are red colored growing from a weak central root. Leaves are rounded, deeply lobed with a waxy appearance that makes dense infestations easy to recognize. Flowers are pink, 5 petaled and grow interspersed with the leaves. It sprouts in early fall with the first heavy rainstorms of the season and by early spring, plants become very pronounced. During April and May, dense low-lying patches form and flowering commences. By late June and July, seed formation is completed and the plant material melts back into the forest floor. The seeds are small and rapidly transported to non-infested areas on boots, vehicles, and by wildlife. Shiny geranium grows in the Pacific Northwest predominantly as an understory species intermixed with grasses, forbs, and moss. Oak woodlands and forest openings are ideal locations for this plant to establish and dominate. Conifer forests offer suitable habitat though dense second growth plantations often create excessive shade, limiting growth and density.
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Basic Info: Silverleaf nightshade
Solanum elaeagnifolium
Designation: List A
Documents: Profile Risk Assessment Distribution
Introduction: Silverleaf nightshade is a perennial that flowers from midsummer to frost. Flowers are violet to light blue, up to an inch wide, fused petals with yellow centers. It grows from 1 to 3 feet tall. Leaves are narrow and, along with the stems, covered with dense, hairs that give foliage a gray or silvery appearance. Creeping stems produce young shoots that are a dusky, silver-gray and resembles seedlings but do not have cotyledons. Fruits are yellow or dull orange berries, which may eventually turn blackish. It reproduces by seeds, creeping roots, and root fragments. Dense stands reportedly produced 100 million seeds per acre per year. Wind, water, birds, vehicles, machinery, agricultural products, and gracing animals can carry seeds. Silverleaf nightshade became established along railroad tracks in California after it was swept from railway cars. Since established silverleaf nightshade is so difficult to control, early detection and prevention is the key.
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Basic Info: Slender flowered thistle
Carduus tenuiflorus
Designation: List B
Documents: Profile Distribution
Introduction: Annual or sometimes biennial; blooms May to June. Grows 1 to 4 feet tall. Stems have spiny wings. Leaves deeply cut into 2 to 5 pairs of lobes and undersurface slightly woolly. Flowers purplish to pinkish, borne in cylindrical heads either solitary or in clusters of 2 to 5. Bracts hairy; fruits from outer part of flower head gray, inner portion are yellowish to tan. Nearly identical to Italian thistle, but has larger flower clusters.
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Basic Info: Small broomrape
Orobanche minor
Designation: List B
Documents: Profile Distribution
Introduction: Annual; blooms within a week of plant emergence. Grows 6 to 12 inches tall. Like other parasitic plants, small broomrape lacks chlorophyll. The flower stalk is yellowish-brown, unbranched with a purplish tint. Leaves look like small triangular scales. Flowers pinkish, yellow or white in color and arranged in an elongated spike.
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Basic Info: Smooth cordgrass
Spartina alterniflora
Designation: List A, List T
Documents: Brochure Profile Distribution
Introduction: Smooth cordgrass is a salt-tolerant perennial aquatic grass species growing strongly erect to 5 feet tall. When young, the leaves are flat without a prominent midrib and tapering to a sharp tip. Stems are round with joints, hollow between the joints and often red at the base of healthy young plants. The roots are white and fleshy with underground runners (rhizomes) that spread outward aggressively. Flowers are arranged in compact spikes 10-20cm long. Seeds are produced in the fall and dispersed in water, though viability is usually less than a year. Smooth cordgrass grows on intertidal mud or sand flats that have minimal wave action; it can occur as low as eelgrass beds in the intertidal zone.
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Basic Info: Smooth distaff thistle
Carthamus baeticus
Designation: List A
Documents: Profile Risk Assessment Distribution
Introduction: This thistle is a winter annual that flowers in July to August. It grows up to four feet tall. Smooth distaff is very similar to woolly distaff thistle except that it has a smaller pappus, is less hairy, and the seedling leaves are more deeply lobed. Stems of smooth distaff are white to straw-colored, usually sparsely covered with woolly and minutes glandular hairs, especially at the bases of flower heads. Stems often persist through winter, longer than most other thistles. Flower bracts and seeds remains in old flower heads that can help with species identification. They prefer disturbed, open sites of grasslands, pastures, and agricultural lands, especially grain fields. Inhabits many soil types. Most seeds disperse passively near the parent plant, but some remain in the seed heads that are then spread by animals and machinery. Seeds are viable for up to 8 years under field conditions.
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Basic Info: South American waterweed
Egeria densa
Designation: List B
Documents: Profile Distribution
Introduction: South American waterweed is a perennial submerged aquatic weed growing rooted to lake bottoms reaching for the surface in water depths up to 7-8 feet. Dark green leaves are up to one inch long, a quarter inch wide, joined in whorls of four to eight at each node giving it a very leafy appearance. Flowers are small, white and three-petaled, emerging above the water's surface. Reproduction is primarily by plant fragments.
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Basic Info: Spanish broom
Spartium junceun
Designation: List B
Documents: Profile Distribution
Introduction: Spanish broom is a perennial leguminous shrub growing up to 7 feet high. It is an attractive plant, historically used as an ornamental. It is similar in appearance to Scotch broom except Spanish broom’s stems are thicker and rougher, it has very few leaves, and the flowers are larger and fewer in number. It flowers from April through June. In its native range, stems and fibers are used to make baskets, mats, ropes, and paper. Flowers were used for yellow dye and provide oil for perfume. Seeds can remain viable in the soil for more than 80 years.
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Basic Info: Spanish heath
Erica lusitanica
Designation: List B
Documents: Brochure Profile Distribution
Introduction: Spanish heath is a woody, upright, perennial evergreen shrub, (tree heather) growing up to 10 feet tall (3 m). Leaves are light green, needle like, 3-7 mm long and arranged around the stem in groups (whorls) of three to four. Blooms are a showy mass of small, white to pink, bell (tubular) shaped flowers. Plants begin flowering in December continuing until April. Large plants produce millions of easily transported seeds. These seeds are dispersed by wind, water, animal or human transported.
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Basic Info: Spikeweed
Hemizonia pungens
Designation: List B
Documents: Profile Distribution
Introduction: Spikeweed is an annual that blooms July to September. This plant grows 1 1/2 to 2 feet tall and has basal leaves that are pale, straw colored, stiff and several inches long with narrow lobes. Stem leaves 1/2 inch long or less and sharp pointed, bearing dwarf stems in their axils. Flower heads yellow, 1/3 inch broad and borne at the tips of short leafy branches. It is a truly armored-looking plant.
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Basic Info: Spiny cocklebur
Xanthium spinosum
Designation: List B
Documents: Profile Distribution
Introduction: The plant is a well armored summer annual growing 3-4 feet tall. The leaves covered with short white hairs, white-veined above, 1 to 3 inches long and have 2 short lobes and a 3-forked spine at the junction with the stem. Male flowers are segregated from the female by being located in the uppermost parts of the plant and clustered. Female flowers are below male flowers and form a beaked bur that bears many small hooked bristles.
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Basic Info: Spotted knapweed
Centaurea stoebe
Designation: List B, List T
Documents: Brochure Profile Distribution
Introduction: Spotted knapweed is a short-lived perennial growing up to 3 feet tall. Bloom time occurs midsummer to fall. It is a multi-stemmed plant topped with purple or sometimes cream colored flowers. The tips of flower head bracts are usually black, thus the name spotted. Seeds dispersed by wind, water, animals, and people. Spotted knapweed is also well documented to exude allelopathic compounds into the soil to restrict competition.
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Basic Info: Spurge laurel
Daphne laureola
Designation: List B
Documents: Brochure Profile Distribution
Introduction: Spurge laurel is an attractive ornamental plant known for its spiraling evergreen leaves and greenish-yellow, bitter-fragrant flowers. Larger patches emit an unpleasant odor. Flowering occurs in late winter-early spring, producing clusters of blue berries during the spring. The one-seeded drupes are eaten and dispersed widely by birds and small mammals. Shrubs reach a height of 0.5-1.5 meters. This weed tolerates low light levels from partial to deep shade. It prefers better-drained clay loams and forest loams with neutral to acidic soils. Escaped populations form dense stands mostly under tree canopies.
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Basic Info: Squarrose knapweed
Centaurea virgata
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Squarrose knapweed is a long-lived perennial knapweed growing 1½ to 3 feet tall. It is multi-branched, erect, with much slender, small, pink to rose-colored flowers that dislodge readily from the plant. Dispersal is unique among knapweeds as mature plants often break off and tumble in the wind dispersing intact seedheads across the landscape. Recurved flower bracts aid dispersal also by attaching to fur and clothing. Squarrose knapweed often grows on degraded rangeland soils and is more adaptable to drought and cold temperatures than spotted and diffuse knapweeds.
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Basic Info: St. Johnswort
Hypericum perforatum
Designation: List B
Documents: Profile Distribution
Introduction: This tansy ragwort look-a-like herb grows 1 to 2 ft. tall. Stems erect, numerous branched, somewhat 2 ridged, rust-colored and woody at their base. Leaves are opposite, oblong, not over 1 in long and covered in transparent dots. Flowers are 3/4 inch in diameter, bright yellow, numerous in flat-topped cymes with five petals with occasional small black dots around the edges. It blooms June through July. It is perennial, dying back each winter to a sparse low-growing plant.
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Basic Info: Sulfur cinquefoil
Potentilla recta
Designation: List B
Documents: Profile Distribution
Introduction: Sulfur cinquefoil is a perennial buttercup species growing 1 to 2 feet tall. Bloom time occurs from May to June. Leaves are compound with 5 to 7 leaflets on each leaf. Stem leaves have a very upright growth habit; one of its significant characteristics Flowers are light yellow with 5 petals.
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Basic Info: Swainsonpea
Sphaerophysa salsula
Designation: List B
Documents: Profile Distribution
Introduction: Perennial; flowers from May to July. It grows as a creeping or spreading plant with compound leaves. The numerous leaflets are oval shaped and hairy. Flowers are 1/4 to 1 inch long and orange-red. Many seeds are produced in bladder-like translucent pods.
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Basic Info: Sweet briar rose
Rosa rubiginosa
Designation: List B
Documents: None AvailableRisk Assessment Distribution
Introduction: Sweet Briar Rose is Eurasian in origin and is highly invasive to dry rangelands in Oregon. It will compete with native vegetation in riparian areas. Deciduous shrub, grow erect up to 8 feet, dense, large oval based down curving thorns on stem. Leaves alternate, compound, 5-9 leaflets, margins double serrated. Flowers mostly pink, sometimes white, borne singly or 2 to 4 per cluster and aromic. Fruit orange to scarlet, ovoid to elliptical and smooth. Dog Rose is Eurasian in origin and is highly invasive to dry rangelands in Oregon. Deciduous shrub, erect up to 8 feet, dense, large oval down curving thorns on stem. Sweetbriar and dog roses look very similar. They are both big brushy round shrubs and they both have nickel sized fruit. Sweetbriar rose has hairs on its sepals and underneath the leaves. Dog rose is not hairy or glandular at all. The leaves of sweetbriar rose have a sweet smell while dog rose leaves are not scented. Dog rose has pointier leaves and white flowers, while sweet briar rose has rounder leaves and pink flowers. Spreads mainly by dispersal of seed by birds. Can colonize and dominate rangelands, pastures and riparian areas.
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Basic Info: Syrian bean-caper
Zygophyllum fabago
Designation: List A
Documents: Profile Distribution
Introduction: Syrian bean-caper is native to the Middle East and central Asia. A bushy herbaceous perennial that may act like an annual in regions with harsh winters. It flowers from May to August and grows up to 1½ feet tall. Leaves somewhat succulent, opposite, compound and each having 2 ovals, 1 inch leaflets. Stems smooth and branched from a thickened woody crown. Flowers are small; compact bunches of five petals each with prominent stamens, salmon to yellow or white with pinkish veins and up to ¾ inch. Flower buds have been used as a substitute for capers. It reproduces by seed and vegetatively from lateral creeping roots.
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Basic Info: Tansy ragwort
Senecio jacobaea
Designation: List B, List T
Documents: Profile Distribution
Introduction: Tansy ragwort is generally a biennial or short-lived perennial; blooming midsummer to fall. It grows 1 1/2 – 4 feet tall. Leaves dark green, deeply lobed. Flowers are numerous, and bright yellow. Reproduction is entirely by seed. Mowed or grazed plants will regenerate to become a short-lived perennial when moisture conditions are adequate. Tansy ragwort’s seeds can lay dormant in the soil for 15 years.
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Basic Info: Taurian thistle
Onopordum tauricum
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Taurian thistle is a vigorous biennial, or short-lived perennial with coarse, spiny leaves and conspicuous spiny-winged stems. The plants are a nearly florescent lime-green in color with large, mostly singular flower heads at the terminals of the main and side stems. The bright purple flower heads are 3 to 4 inches in diameter. The heads consist of numerous spiny-tipped bracts resembling an artichoke before the bud opens. The leaves are typically covered with short, sticky-glandular hairs, acutely triangular, with 6 to 8 pairs of spiny-toothed lobes. Taurian thistle seedlings typically appear after the first fall rains and develop into large rosettes the next growing season. From this rosette and taproot an 8 foot tall plant develops. Dead stems can persist into the next season with spines attached. Taurian thistle reproduces only by seed. Most seeds germinate in the fall but can germinate through out the summer. Buried seed can remain viable in the soil seed bank for at least 7 years and possibly to 20 years or more. Wind, water, animals, and vehicles can disperse seeds.
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Basic Info: Tree of heaven
Ailanthus altissima
Designation: List B
Documents: Profile Distribution
Introduction: Tree-of-heaven can reach a height of 25 to 50 feet. The leaves are often mistaken for sumac, with prominent leaf scars on the bark remaining when they are detached from the stem in the fall. The flowers are small, yellowish to reddish in color, and have five petals. Tree-of-heaven has a rank odor, similar to foul smelling peanuts.
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Basic Info: Turkish thistle
Carduus cinereus
Designation: List A
Documents: Profile Risk Assessment Distribution
Introduction: Turkish thistle is a native of the Irano-Turanian Region which extends from Turkey east to the Himalayas. It has only recently been documented in North America (2007) with its known distribution limited to the Snake River Canyons of NE Oregon and East Central Idaho. The plant is closely related to Italian thistle (Carduus pycnocephalus) and was misidentified as such until 2014. Careful botanical scrutiny and genetic profiling since have led to its identification as a unique species of the genus carduus.
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Basic Info: Velvetleaf
Abutilon theophrasti
Designation: List B
Documents: Profile Distribution
Introduction: Velvetleaf is an annual that blooms June through October. It grows two feet to seven feet tall and is completely covered in soft hairs. Its leaves are alternate, heart-shaped and five or more inches in width. Velvetleaf flowers are yellow, five petaled and solitary and grow in the leaf axils.
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Basic Info: Ventenata grass
Ventenata dubia
Designation: List B
Documents: Profile Risk Assessment Distribution
Introduction: Ventenata is a winter annual that produces seed heads in May through June. Ventenata grass is a relatively new invader in the Pacific Northwest with the first confirmed siting in 1952 in Washington State. Since that initial siting, the plant has rapidly increased its range throughout the West including most counties in Oregon. Reports conclude that it invades habitats similar to Medusahead rye and cheatgrass but thrives better in slightly wetter conditions enabling it to include western Oregon in its ecological range. Rich in silica, the grass provides very poor forage, contaminates hay crops, reduces small grain yields, reduces rangeland productivity and outcompetes most other native and non-native grasses in its optimum ecological zone.
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Basic Info: Water primrose
Ludwigia hexapetala, peploides
Designation: List B, List T
Documents: Brochure Profile Distribution
Introduction: Water primrose are perennial occurring in marshes, swamps, ditches, ponds, and around lake margins, where they form dense floating mats up to 3 feet tall, crowding out native species. The stems root freely at the nodes either in the water or in damp soil. Reproduction occurs both by seeds and vegetatively through fragmentation. It produces light green, floating stems early in the season with rosettes of smooth, shiny, rounded leaves. Later the stems become erect, reddish-brown, and produce elongated, willow-like, pointed leaves arranged alternately along the stems. Flowers are solitary, up to an inch in diameter, having five to six bright yellow petals. Flowering occurs from mid to late summer and continues until a killing frost
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Basic Info: Water soldiers
Stratiotes aloides
Designation: List A
Documents: Profile Distribution
Introduction: Water soldier has an interesting growth habit: during the growing season plants float or sit partially emergent and in winter plants sink to the sediment. Water soldier may root lightly in the sediment, but plants are often free-floating. Some populations reportedly remain rooted year round in oligotrophic waters. Sharp-spines edge the margins of each leaf. Leaves are slightly triangular to linear, tapering to a narrow point and forming large rosettes that resemble spider plants, aloe or the tops of pineapples. Plants are dioecious; male flowers are borne in clusters of three to six, and female flowers are solitary (rarely with two flowers). Showy, white, three-petaled flowers are held above the water on peduncles.
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Basic Info: Welted thistle
Carduus crispis L
Designation: List A, List T
Documents: None AvailableRisk Assessment Distribution
Introduction: Welted thistle is a native to Europe and Asia. It can grow as an annual or biennial, 30–150 cm tall depending on growing conditions. Stems are openly branching, hairy with curled hairs to nearly smooth. Stems have spiny wings to 1.5 cm wide, and sport wing spines 3 mm long. The leaves have winged petioles at their base. Leaf blades are 10–20 cm long with spiny-toothed margins. Flower heads are borne singly or in groups of 2–5, 15–18 mm wide. Flower peduncles are spiny-winged to near apex or throughout, to 4 cm wide. Flower corollas can be either purple or white. Flower parts are both male and female. Flowering occurs July through September. Insect pollination is required. Reproduction is entirely by seed. The first record of welted thistle occurred in the Eastern U.S. in 1974. In 2016, a new western infestation was detected in Wallowa County, Oregon. Carduus crispus closely resembles the more common C. acanthoides (plumeless thistle).
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Basic Info: West Indian sponge plant
Limnobium laevigatum
Designation: List A
Documents: Profile Distribution
Introduction: Spongeplants typically form floating mats of vegetation, but are sometimes lightly rooted in shallow muddy areas; their appearance varies considerably according to their density: in uncrowded growing conditions the leaves float flat along the water and have distinctive aerenchyma tissue on their lower surface. When crowded, spongeplant’s petioles lengthen to hold laminas (leaves) 20-30 cm (8-12 in) above the water; these older, crowded spongeplants resemble water hyacinth (Eichhornia crassipes), but can readily be distinguished by spongeplant’s small white flower and the lack of a swollen petiole bases.
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Basic Info: White bryonia
Bryonia alba
Designation: List A
Documents: Profile Risk Assessment Distribution
Introduction: White bryonia is a vigorous herbaceous perennial vine resembling kudzu. Mature plants smother small trees and shrubs with dense growth shading out any vegetation it grows on. Vines emerge each spring from a large fleshy parsnip-shaped tuber growing up to 30 feet each season. The herbaceous vines sport tendrils and alternate, palmate, lobed leaves. Flowers are small, greenish-white, five petaled and produced in clusters forming dark-blue berries later in the summer. When crushed, the berries emit a bad odor. The plant leaves and vines resemble the native western wild cucumber, though the native cucumber has a golf-ball sized fleshy pod, very unlike the black berries of white bryonia. Seed dispersal is rapid, aided by birds that ingest the blue-black seeds transporting them short and long distances.
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Basic Info: Woolly distaff thistle
Carthamus lanatus
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Woolly distaff thistle is an erect winter annual with rigid stems. It flowers from July through August. It grows up to 3½ feet tall, has spiny pointed leaves that are alternate. The flower head has many long, sharp leaf-like bracts just below the yellow flowers. The rigid stems with old flower heads and leaves often persist through winter and often longer.
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Basic Info: Yellow archangel
Lamiastrum galeobdolon
Designation: List B
Documents: Profile Distribution
Introduction: Leaves are typically variegated with silvery-grey markings and are oval-shaped and toothed. Stems are square, leaves are opposite. Leaves are hairy and coarsely toothed. Flowers are small, yellow and tubular; they grow in pairs of clusters close to stems between leaves on flowering stems that are 1 to 2 feet tall. Distinctive, non-menthol and somewhat unpleasant odor.
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Basic Info: Yellow flag iris
Iris psuedocorus
Designation: List B
Documents: Brochure Profile Distribution
Introduction: Yellow flag is a very showy species growing 3-4 feet in height with the most vigorous growth attained in the wettest environments. The leaves are long, flattened and sword-like, typical of most iris. Large plant clumps are formed from the lateral growth of rhizomes sometimes attaining 20 feet in width. Flowers are produced on erect plant stalks with multiple flowers produced on each. Fruit capsules are large, 3-angled and up to 4 inches in length. Disk-like seeds are shed from the capsules throughout the fall and winter. Floating mats of seed can be observed in backwaters and marshes aiding dispersal.
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Basic Info: Yellow floating heart
Nymphoides peltata
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Yellow floating heart is an aquatic emergent perennial with creeping rhizomes and stolons and floating heart-shaped leaves. The 3-5 inch diameter leaves are much smaller than the native yellow pond lily common in the Northwest that sports 12-14 inch leaves. Yellow floating heart is also distinguished by having smaller blooms than the native. Flowers are 1-2 inches in diameter, bright yellow with 5 fused petals. The native pond lily flowers are globular and larger. Flowering occurs from May to October. Reproduction is by seed and by plant fragments.
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Basic Info: Yellow hawkweed
Pilosella floribundum (Hieracium)
Designation: List A, List T
Documents: Brochure Profile Distribution
Introduction: Yellow hawkweed is a perennial that flowers in June to July in lower elevations. It grows 10 to 36 inches tall. Leaves are hairy, spatula shaped and almost exclusively basal. Flower heads clustered, yellow, ½ an inch wide, and number up to 30 per plant. Extensive stolons form dense mats of vegetation. King-devil hawkweed, yellow hawkweed, and meadow hawkweed are all very similar yellow hawkweed and difficult to classify. Native hawkweeds have numerous stem leaves, lack stolons and generally have solitary flowers.
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Basic Info: Yellow nutsedge
Cyperus esculentus
Designation: List B
Documents: Profile Distribution
Introduction: Yellow nutsedge is an erect, grass-like perennial, characterized by its shiny yellowish green leaves, triangular stem, golden-brown flower head and shallow rhizomes (horizontal underground stems) that produce many nut-like tubers. Stems 1/3 to 3 feet tall are erect, hairless, unbranched and triangular in cross-section. The leaves are light yellowish-green 4 to 12 inches long or longer, 1/8 to 1/2 inch wide, with a prominent mid-vein, a waxy surface and a gradually tapering, pointed tip. Young seedlings are often confused with grasses. This species reproduces primarily by tubers and less often by seeds. Rhizomes help to enlarge patches.
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Basic Info: Yellow starthistle
Centaurea solstitialis
Designation: List B
Documents: Profile Distribution
Introduction: Yellow starthistle is a gray-green to blue-green plant with a deep, vigorous taproot. It produces bright, thistle-like yellow flowers with sharp spines surrounding the base. Yellow starthistle grows to heights varying from 6 inches to 5 feet. The stems of mature plants are rigid, spreading, and typically branching from the base in open areas. Stems and leaves are covered with a loose, cottony wool that gives them a whitish appearance. Stems appear winged due to leaf bases that extend beyond the nodes. Basal leaves are 2 to 3 inches long and deeply lobed. Upper leaves are short (0.5 to 1 inch long) and narrow with few lobes.
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Basic Info: Yellow toadflax
Linaria vulgaris
Designation: List B
Documents: Profile Distribution
Introduction: A perennial herb that blooms from summer to fall. It grows one to two feet tall and has pale green leaves that are narrow and pointed at both ends. Its flowers are orange and yellow and snapdragon-like.
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Basic Info: Yellowtuft
Alyssum Corsican, A. murale
Designation: List A, List T
Documents: Brochure Profile Risk Assessment Distribution
Introduction: Alyssum is fast growing perennial, reaching reproductive maturity within one or two years. A. murale’s leaves are gray-green oval or spatula-shaped leaves are 0.5-1.0 cm long and are covered with tiny hairs. A. corsicum is very similar, although the leaves of this species are more oval in shape and have a dense covering of silvery hairs, giving them a pale gray or white appearance. Plants of both species produce hundreds of small, bright yellow flowers on branched umbels in early summer. Because most leaves are shed prior to the initiation of flowering, the two species look almost identical when in flower. Both species produce the papery, circular to oval flattened fruits, each with a single flattened seed
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Resources

Oregon Noxious Weed Policy and Classification
'A', 'B,' and 'T,' listed weeds for the state of Oregon. The State Noxious Weed List is used to prioritize activities at the state level and provide direction in the development of county weed lists that guide local control programs. This list is part of a Noxious Weed Policy and Classification System and is jointly maintained by the Oregon State Weed Board and the Noxious Weed Control Program.