Weeds in Gardens, Landscapes & Property

Blackberry takes over neglected areas. Plants live for many years (perennial). Canes grow up to 15 feet tall. They grow on the ground or through vegetation or structures.

Blackberry thorns are large and dangerous. If you are injured by a blackberry thorn, clean the wound with soap and water.

Birds and mammals eat the berries and spread seeds widely.

 Leaves are palm-shaped with a central stem. Each leaf has five leaflets (sometimes three) with toothed margins.

Blackberry flowers have five petals in shades of white to pink. They are very attractive to honey bees and other pollinators.

Mature broom shrubs are three to ten feet tall with dense, slender stems and yellow flowers. Many broom shrubs often grow together.

The flowers are yellow and about 1 inch long, and typical of many plants in the pea family.

Broom species are nitrogen-fixing plants. This trait helps broom grow in areas with poor quality and disturbed soils.

Seed pods (fruits) are hairy along the seam and turn from green to brown as they dry.

A mature Scotch broom plant produces about fifteen thousand seeds per year. The seeds remain viable in the soil for ten or more years.

Scotch Broom Distribution & Reporting in Oregon

Red shows counties in Oregon where Scotch broom is widespread. Yellow shows counties where it has limited distribution. Green shows an area where Scotch broom has been eliminated. Grey areas show counties where it is not known to occur.

Reporting Invasive Species

You can help Oregon agencies track the distribution of invasive species.

If you know about an infestation of Scotch broom, please report it to the Oregon Invasive Species Hotline. Call 1-866-INVADER (1-866-468-2337). Or use the online reporting form.

Butterfly bush establishes in areas with disturbed soil. It grows along roads and riverbanks and in pastures and recently burned areas.

Butterfly bush grows in harsh conditions such as cracks in pavement and gravel roads. The photo shows a butterfly bush growing out of a chimney.

Butterfly bush’s leaves grow alternately along the stems. Leaves are 4-10 inches long and 1-3 inches wide. They are dark green on top and white-pale green underneath.

Flower spikes form at the tip of the branches. Flowers vary in color from white to purple and and blue. The flowers attract butterflies.

Butterfly bush spreads via seeds. Seeds can form during its first year. They are viable for 3 to 5 years.

Canada thistle grows slender stems 3-5 feet tall. Many stems grow together to form dense patches.

Mature leaves are 2-8 inches long. Leaves are alternately arranged on the stem. They are lobed with stiff spines.

Each seed has a white structure (pappus) that aids wind dispersal. Seeds sprout on or just below the soil surface. Seeds remain viable in the soil for many years.

Canada thistle grows a large root system. The photo shows a box about 4 feet above the ground surface. A side of the box has been removed to show the roots. Roots grow laterally for dozens of feet and about 10 feet deep. The root system stores energy and supports vigorous shoot growth.

New shoots emerge from the root system during warm periods.

The photo shows a large, flowering cherry laurel shrub in a landscape.

Leaves grow alternately on stems. They are leathery. The leaves are oval-shaped and 2-8 inches long. The underside of the leaves is lighter colored than the top. Flower clusters grow upright 2-5 inches tall. The white flowers have five petals.

Dark colored berries are about ½ inch wide. Birds eat the berries and spread the seeds.

Common hawthorn grows 6-30 feet tall as a thorny, deciduous small tree or shrub. It often forms a thicket.

Leathery leaves grow alternately on stems. They are 3-7 lobed, 1-2 inches long.
Flowers occur on short stems clustered in flat-topped groups of 10-20. Each flower has five sepals and five white petals that age to light pink.

Common hawthorn flowers are white or pink with five petals. The flowers have a strong odor.

The thorns of common hawthorn are large and dangerous. If you are injured by a thorn, clean the wound with soap and water.

Fruit is a ¼- to ½-inch round, and dark red to crimson that persists into late winter.
Birds eat the fruits and spread the seeds.

Leaves and flowers grow from a tap root. Yellow flowers grow 1-2 inches wide.

Jagged leaves grow 2-10 inches long and look like lion teeth.

Flowers mature into a ball of seeds. The seeds detach and float away.

English holly has waxy, evergreen leaves with spines along the edges. Wear thick gloves and clothing to handle holly plants. The spines hurt.

Red holly berries are about 1/4 inch in diameter. Birds eat the berries and spread the seeds.

There are numerous cultivars of English holly with distinct traits. The photo shows a cultivar with variegated leaves.

False brome germinates in late fall and spring. Plants mature into compact bunches of bright-green leaves throughout spring, summer, and fall. Plants remain green in mild winter temperatures, and in some colder winter locations, the leaves and stems die and become white thatch.

Individual false brome plants produce dozens to hundreds of seeds. Seeds are spread by animals, people, or equipment that move through infested areas. Most seeds germinate within a year or two.

False brome flowers in summer. Groups of flowers grow in pale green, drooping spikelets that are attached directly to the flowering stem. Spikelets are 1-2 inches long. There are 5-10 spikelets per flowering stem, as shown in the photo. Each spikelet has 7-17 individual flowers.

False brome is expanding quickly in closed-canopy forests, woodlands, oak savannah, grasslands, roadside trails, and disturbed areas.

It degrades habitat by suppressing native plant understory growth.

False Brome Distribution & Reporting

Red areas show Oregon counties where false brome is widespread. Yellow areas show counties where it has limited distribution. It is not known to occur in the grey areas.

Reporting in Oregon

You can help Oregon agencies track the distribution of invasive species.

If you have false brome growing on your property, please report it to the Oregon Invasive Species Hotline. Call 1-866-INVADER (1-866-468-2337). Or use their online reporting form.

Field bindweed forms a dense mat of vines and leaves on the ground. It also climbs and overtakes other plants, fences, and trellises.

Field bindweed forms a dense mat of vines and leaves on the ground. It also climbs and overtakes other plants, fences, and trellises.

Field bindweed spreads with vines that grow across the ground and roots underground.

Field bindweed spreads with vines that grow across the ground and roots underground.

Mature field bindweed plants produce dozens to hundreds of seeds shown in the photo. Seeds remain viable in the soil for many decades.

Mature field bindweed plants produce dozens to hundreds of seeds shown in the photo. Seeds remain viable in the soil for many decades.

Stems grow from three to four feet tall and wide. White flowers form at the top of the stems in the spring.

Seeds germinate in the late winter or early spring and grow into rosettes with kidney-shaped, toothed leaves. Individual plants live as rosettes one year.

Garlic mustard plants live for two years. In the spring of its second year garlic mustard grows stems and triangular leaves with toothed edges. The leaves are arranged opposite each other along the stem. White flowers with four petals grow at the top of the stems.

Garlic mustard spreads quickly by seed. Larger, mature plants make up to eight thousand seeds. The seeds form in narrow pods in the late spring. By late June, the seed pods pop open, and spread the seeds.

Garlic mustard quickly dominates natural areas such moist forests and dry woodlands. It suppresses native plant growth. The loss of native plants reduces the habitat value of the area.

Garlic Mustard Distribution and Reporting in Oregon

The red area on the map shows where garlic mustard is widespread. Yellow areas show counties where it has limited distribution. Grey areas show counties where it is not known to occur.

Reporting Invasive Species

You can help Oregon agencies track the distribution of invasive species.

If you know about an infestation of garlic mustard, please report it to the Oregon Invasive Species Hotline. Call 1-866-INVADER (1-866-468-2337). Or use their online reporting form.

Have white, umbrella-like, flowerhead (umbels) that are 18-24 inches across

Stems are 2-4 inches in diameter and hollow. Have purplish-red blotches and bumps. Covered with stiff hairs.

Forms dense patches that emerge in later winter and spring. Stems die and remain standing late summer through early winter.

Mature gorse shrubs are three to ten feet tall with dense, slender stems and yellow flowers. Many gorse shrubs often grow together.

The flowers are about one inch long and typical of many plants in the pea family.

Gorse spines are large and dangerous. If you are injured by a gorse spine, clean the wound with soap and water.

Hedge bindweed forms a dense mat of vines and leaves on the ground. It often climbs and overtakes other plants, fences, and any adjacent structure.

Mature plants have triangular or arrow-shaped leaves that range from 2-5 inches long.
The bottom of hedge bindweed leaves are squared off or rounded compared to field bindweed. The vines are often reddish-tinged and grow up to 10 feet long.

Hedge bindweed spreads by vines supporting flowers that are 2.5-5 inches long and 1-2 inches wide. Look for flowers in late spring throughout summer. The flowers produce 2-4 grey-to-brown-black seeds that persist for decades in the soil.
Hedge bindweed also spreads by rhizomes.

The photo shows a hedge bindweed plant with rhizomes sprouting new above-ground shoots.
Hedge bindweed’s root system may spread horizontally up to 10 feet and many feet deep. The extensive root system allows the plant to avoid drought conditions. Look for seedlings and shoots from mature plants in early spring.

Hedge bindweed plants produce dozens to hundreds of seeds shown in the photo. Seeds remain viable in the soil for decades.

Plants grow about 12–18  inches tall. Leaves are shaped like an arrow with a pale green midrib and veins.

Flowers are a yellow-cream color and unpleasant smelling. They have a stubby spike and a large, white, funnel-shaped structure.

Fruits are tightly clustered on spikes. Fruits turn from green to orange-red, and contain seeds that spread it to new areas.

Stems extend below the soil surface. Forms white tubers and roots. They are difficult to remove.

Italian arum forms dense patches that are visible in fall through winter. In warm, dry summer months, the stems and leaves die back and are not visible above ground.

The leaves grow opposite one another along the red stems.

Leaves grow as long as 15 inches and 11 inches in width. But leaves can be smaller, as shown in the photo.

Flowers are abundant in mid to late summer. They grow on branches in the top 1/3 of the plant. Flowers make seeds that result in new plants. But seedlings play a small role in establishing new stands.

Stems are long, hollow, and segmented like bamboo. They grow from 4-15 feet tall and are often arched.

Knotweed spreads far beyond shoot growth with underground root structures (rhizomes). Stems and root pieces broken or cut away from rooted plants can make new plants.

In the fall and winter, knotweed stems die and remain standing. New growth emerges from the soil in early spring.

Forms dense patches that are visible in later winter and spring. Above-ground stems die back and are not visible during summer and fall.

Plants grow about 6-8 inches tall from the base (rosette).

Yellow flowers have yellow sepals (resemble petals).

Small, pale, bulbs (called bulbils) form on the stems. They attach to your shoes, clothes, and equipment. Bulbils are carried by flowing water to new areas.

Pokeweed often matures into a shrub or small tree. But it is not woody and dies back with the onset of winter.

Stems grow two to eight feet each year from a white, fleshy root. They are colored green, red, or purple. The hollow stems are smooth and grow up to 4 inches across.

Each leaf is 5-20 inches long. The leaves are about one third as wide as they are long. They alternate along the stem. The leaves smell bad when crushed.

The flowers mature into green berries. In late summer or early fall, berries turn dark purple. The berries occur as a drooping bunch that resembles a grape cluster. Berries are poisonous. Do NOT eat the berries.
Birds eat the berries and scatter the seeds. New plants grow from the seeds.

Pokeweed seedlings have alternate leaves. The leaves are red on the underside.

Shoots emerge from established root crowns in the spring. The shoots resemble seedlings, but are thicker and clustered together as shown in the photo.

Shiny geranium grows six to eighteen inches tall. It often forms dense mounds that smother other vegetation. It favors landscapes and the sides of roads, trails, and forest edges.

Stems range from green to red, depending on environmental conditions. The stems are hairless.

Plants turn red in the late spring and into summer. The green structures are mature flowers (capsules) that contain shiny geranium seeds.

Shiny geranium forcefully ejects its tiny seeds from their capsules. This trait helps spread the seeds to form dense carpets. The seeds are textured. They stick to shoes, clothing, and pets. The seeds are carried to new areas.

Shiny Geranium Distribution & Invasive Species Reporting in Oregon

Red areas show Oregon counties where shiny geranium is widespread. Yellow areas show counties where it has limited distribution. Grey areas show counties where shiny geranium is not known to occur.

Invasive Species Reporting

You can help Oregon agencies track the distribution of invasive species.

If you know about an infestation of shiny geranium, please report it to the Oregon Invasive Species Hotline. Call 1-866-INVADER (1-866-468-2337). Or use their online reporting form.

The leaves are shiny and lobed. Shiny geranium has small, pink flowers with five petals.

Tansy ragwort stems grow 1.5-4 feet tall. It forms dense stands. Tansy ragwort thrives in areas with disturbed soil.

Its leaves are dark green on top and lighter underneath. They have deeply lobed leaves with a ruffled look.

Tansy ragwort has yellow, sunflower-family flowers. They have 15-ray flowers that look like petals.

After a tansy ragwort seed germinates, plants form a rosette. The rosettes have light-green leaves that grow close to the ground. The leaves are lobed.

The cinnabar moth (Tyria jacobaeae) was introduced to the Pacific Northwest. It helps to control tansy ragwort. The larvae of the moth defoliate tansy ragwort. See below for information about biocontrol.

Tree-of-heaven is a fast-growing deciduous tree. It grows as a single tree or as many stems as shown in the photo.

Leaves have a large central stem with leaflets arranged opposite each other along the stem. A single leaf is 1-3 feet long.

Established female trees produce hundreds of thousands of seeds each year. The seed forms inside clusters of samaras (seed pods). They remain on the tree through winter.

Mature trees grow as a single trunk up to 100 feet tall. Bark is textured and colored shades of brown and grey as trees age.

Tree-of-heaven has an extensive root system, including shallow roots. The shallow roots produce many shoots that emerge far from the trunk of the established tree.

Tree-of-Heaven Distribution & Invasive Species Reporting in Oregon

The yellow areas on the map of Oregon show counties where tree-of-heaven has limited distribution. Grey areas show counties where it is not known to occur.

Invasive Species Reporting

You can help Oregon agencies track the distribution of invasive species.

If you know about an infestation of tree-of-heaven, please report it to the Oregon Invasive Species Hotline. Call 1-866-INVADER (1-866-468-2337). Or use their online reporting form.

INVASIVE SPECIES ALERT: Spotted Lantern Fly

This invasive insect feeds on tree-of-heaven and damages many agricultural crops. It is established in the Eastern United States. It is not known to occur in the Pacific Northwest at this time. Look for this insect pest and if you find it, report it. Learn more.

Yellow archangel’s leaves are hairy and toothed. They grow opposite each other along the stem. Its leaves are often variegated with silver green markings

Some yellow archangel plants have green leaves. All plants of this species have yellow flowers as shown in the photo.

Once yellow archangel is established, it spreads via stem layering. When nodes on the stem contact the ground or get buried, they sprout roots. The line drawing shows layering. Stem fragments can also take root and establish new plants. Yellow archangel also spreads by seed.

The mature leaves are 2–3 feet long, flattened and sword-shaped, typical of most iris. They may stay evergreen in mild winters.

Yellow flag iris flowers have 3 large downward-spreading sepals and 3 small erect petals. The sepals may have delicate brownish to purple veins. Yellow color may be bright or pale. It blooms from late spring into summer.

The seed pod is up to 4 inches long and glossy green. It contains many flattened brown seeds. Seeds float on the water, and spread yellow flag iris into the surrounding area.

Yellow flag iris spreads by stout rhizomes. They grow rapidly, forming a dense mat.

Flattened brown seeds are about ¼ inch in diameter.

Flowers are bright yellow with long, sharp spines at the base.

Stems are gray-green. The extended leaf bases make the stems appear winged.

Yellow starthistle forms a rosette after germinating. Plants in this stage grow a large taproot.

Yellow starthistle plants grow in dense stands from 6 inches to 5 feet tall.

Yellow starthistle plants can produce thousands of seeds. Up to 95% of seeds are viable. Seeds remain viable in the soil for 3 or more years.