Description:

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.

Life cycle:

Perennial

Height of mature plants

3 feet

Flower color:

White

Bloom time:

May through July

Look-a-likes:

False brome is similar in appearance to a native brome, Columbia brome (Bromus vulgaris). False brome is densely hairy on the leaf blade margin while Columbia brome is sparsely hairy.

Habitat:

It can grow in a variety of habitats including forests, forest edges, woodlands, riparian areas, prairies and roadsides.

Impacts:

It is a fast-spreading, invasive grass that displaces native flora. It can form dense, monotypic colonies in both forest understories and open woodlands.

Noxious Weed Listing:

• WeedWise: Priority
• State of Oregon: Class B
• State of Washington: Class A
• Four County CWMA: Class A

Origin:

Pakistan, Europe, temperate regions of Asia, mountainous regions of tropical Asia, Northern Africa and Macronesia

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
Invasive.org profile
CABI Invasive Species Compendium

Description:

English ivy is an evergreen climbing vine in the Araliaceae (Ginseng) family. It has historically been a common garden ornamental and has more than 400 cultivars. It has escaped cultivation to become highly invasive in forests and natural areas throughout the Pacific Northwest. Native to Europe, these plants are characterized by long viny stems reaching up to 30 m in length, with aerial, clinging small root. English ivy damages desirable vegetation by shading out and smothering plants. English ivy also covers trees making them more susceptible to wind fall due to the additional weight of the ivy in the trees as well as the additional drag of the evergreen leafy vines.

Life cycle:

Perennial

Height of mature plants

This vine climbs into the canopy of mature trees and so can grow very high.

Flower color:

Greenish-white

Bloom time:

Typically blooming during months when not in a purely vegetative state.

Look-a-likes:

In Oregon, three Hedera species have been documented: English ivy (H. helix), Atlantic ivy (H. hibernica), and Persian ivy (H. colchica). However, only English and Atlantic ivy are listed as noxious weeds in Oregon. The invasive plant commonly referred to as English ivy is actually comprised of  both English ivy and Atlantic ivy. Identification and differentiation between the species is complicated because there many cultivated varieties. Both English ivy and Atlantic ivy have been commonly sold as English ivy, but can be differentiated by leaf shape and tiny hairs on the young leaves. These two species can also be differentiated through genetic testing.

Habitat:

The areas most infested by English ivy are urban natural areas, disturbed forests, woodlands, and along stream corridors. Plants grown in moist soils with summer shade and winter sunlight will flourish. Urban forest and natural areas are especially impacted as a result of repeated reinfestation from garden escapees.

Impacts:

Rapid and massive vegetative growth of English ivy vines reaches to treetops and woody ornamentals. It also can displace native vegetation on the forest floor. English ivy frequently becomes intertwined with forest shrubs creating difficulties for manual removal or herbicide use. Removal costs in some Oregon parks have reached $3000 per acre.

Noxious Weed Listing:

• WeedWise: Maintenance
• State of Oregon: Class B
• State of Washington: Class C
• Four County CWMA: Class C

Origin:

Europe

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
King County Noxious Weed profile
CABI Invasive Species Compendium

Description:

Canada thistle is a tall, prickly, creeping rhizomatous perennial with multiple purple flowers. The erect plant stands around 2 to 4 feet tall on rigid, hairy, branched stems that usually die back during winter. This aggressive noxious plant forms dense unisex patches on disturbed land, and produces allelopathic chemical that inhibit growth of other plants.  Canada thistle is native to Europe, not Canada, and can be found throughout the United States.

Life cycle:

Perennial

Height of mature plants

5 feet

Flower color:

Purple

Bloom time:

Flowers appear from June to October.

Look-a-likes:

There are several native and nonnative thistles that resemble Canada thistle. Please see this guide for identification clarification.

Habitat:

Canada thistle can be found in disturbed areas with abundant sun and moist but not wet soils. Crop fields, forest openings, gardens, hillsides, logged areas, pastures, range land, roadsides, stream banks, vacant lots and waste places are the usual infestation locations for Canada thistle. It is found throughout most of the continental United States.

Impacts:

Once established, it spreads quickly replacing native plants. It grows in circular patches, spreading vegetatively through roots which can spread 10 -12′ in one season. It poses an economic threat to the agriculture industry by reducing crop yields.

Noxious Weed Listing:

• WeedWise: Maintenance
• State of Oregon: Class B
• State of Washington: Class C
• Four County CWMA: Class C

Origin:

Europe and Asia

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
Invasive.org profile
CABI Invasive Species Compendium

Description:

Butterfly bush is a deciduous shrub with arching branches that can reach 15 feet in height. The showy flower spikes are often purple, and the leaves and stems are typically hairy. Flowers have 4 petals and are commonly purple with an orange center, but cultivars can be pink, orange, and white. Flower spikes are upright or nodding, reaching a length between 4 to 10 inches. They are fragrant and blooming begins in mid-summer.

Life cycle:

Perennial

Height of mature plants

Up to 15 feet

Flower color:

Commonly purple with an orange center, but cultivars can be pink, orange, and white.

Bloom time:

Typically blooming July through September.

Look-a-likes:

Butterfly bush appears similar to lilac but blooms much later (late summer) than lilac.

Habitat:

While often planted in yards and gardens as an ornamental, butterfly bush can colonize disturbed areas including roadsides, abandoned railroad tracks, pastures, riverbanks, and recently logged forests.

Impacts:

It forms dense thickets, especially along river banks and gravel bars, which crowd out native plants and may alter soil nutrient concentrations. This shrub is difficult to control, can produce seeds during its first year and seeds are viable 3 to 5 years.

Noxious Weed Listing:

• WeedWise: Maintenance
• State of Oregon: Class B
• State of Washington: Class B
• Four County CWMA: Class C

Origin:

China

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
Invasive.org profile
CABI Invasive Species Compendium

Description:

African rue is a multi-branched and bushy perennial of the Caltrop family. 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. 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.

Life cycle:

Perennial

Height of mature plants

18 inches

Flower color:

White

Bloom time:

It can bloom from April through November.

Look-a-likes:

None

Habitat:

African rue primarily grows in deserts.

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.

Noxious Weed Listing:

• WeedWise: Priority
• State of Oregon: Class A,T
• State of Washington: not listed
• Four County CWMA: not listed

Origin:

Africa, South Asia

Present in Clackamas County:

No

Links:

Oregon Noxious Weed Pprofile

Description:

Barbed goatgrass grows 8 to 16 inches tall with few to many culms. 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.

Life cycle:

Annual

Height of mature plants

8-16 inches

Flower color:

N/A

Bloom time:

Typically blooms during May, June, and July.

Look-a-likes:

Aegilops ovata and Aegilops cylindrica are in the same genus as barbed goatgrass and are also listed noxious weeds in Oregon.

Habitat:

Barbed goatgrass invades rangeland, grasslands, and oak woodlands. This species is highly invasive in northern California.

Impacts:

When mature, barbed goatgrass is unpalatable to livestock and can cause injury to grazing animals. Goatgrass infestations can reduce forage quality and quantity by 50 to 75 percent. Because livestock tend to avoid this weedy grass dense stands form that push out natives and desirable forage. Barbed goatgrass is an agricultural concern since it can readily cross with wheat, producing sterile seed and unmarketable wheat.

Noxious Weed Listing:

• WeedWise: Priority
• State of Oregon: Class A,T
• State of Washington: Not listed
• Four County CWMA: Not listed

Origin:

This species is native to Western Asia and Mediterranean Europe.

Present in Clackamas County:

No

Links:

Oregon Noxious Weed Profile
USDA Plants
Global Invasive Species Database

Description:

Tansy ragwort is a tall biennial plant in the sunflower family. It can grow up to 6 feet in height at maturity. The rigid stems of Tansy ragwort are green with an occasional reddish tinge. Plants typically arise from a single stem that becomes branched at the top of the plant, forming flat clusters of bright yellow flowers. The yellow daisy-like flowers have dark yellow to orange centers. Leaves are dark green and ruffled in appearance. Tansy ragwort grows as a rosette in its first year before transitioning into the mature flowering form in its second year of growth. Tansy ragwort can form dense patches, particularly on disturbed sites. This noxious weed is dangerous to humans and livestock due to a poisonous alkaloid (hepatotoxic pyrrolizidine) in its tissue which causes liver damage when ingested.

Life cycle:

Perennial

Height of mature plants

3-6 feet

Flower color:

Yellow

Bloom time:

July to September

Look-a-likes:

From a distance, tansy ragwort can look like common St. John’s wort (Hypericum perforatum), but upon looking more closely, tansy ragwort has large ruffled leaves, whereas St. John’s wort has many small leaves. Also, tansy ragwort has flowerheads with 13 petals, while St. John’s wort has 5.

Habitat:

Tansy ragwort is opportunistic plant often found in disturbed areas. Tansy likes a cool and wet climate, well drained soils and full to partial sun. Patches are found in pastures, fields, grasslands, vacant land, waste places, horse trails, roadsides, rangeland, riparian areas, forested areas, and clear cuts. Areas of greatest concern are improperly managed pastures and disturbed areas.

Impacts:

Prolific in pastures, clear cuts, and disturbed roadside areas, tansy populations can become quite dense. The leaves are toxic to cattle and horses, causing irreversible liver damage. In the 1960’s and 70’s livestock losses in Oregon amounted to 5 million dollars a year. Unlike cattle and horses, sheep appear to be unaffected by ragwort’s toxicity. Once considered Western Oregon’s most economically serious noxious weed, biological controls have reduced the severity of outbreaks below economic threshold levels.

Noxious Weed Listing:

• WeedWise: Maintenance
• State of Oregon: Class B
• State of Washington: Class B
• Four County CWMA: Class C

Origin:

Eurasia

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
Invasive.org profile
CABI Invasive Species Compendium