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Himalayan blackberry thicket in abandoned area

Himalayan 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.

Red-colored Himalayan blackberry cane with large thorns

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

Himalayan blackberry fruits, leaves, and stems

Eric Coombs, Oregon Department of Agriculture, Bugwood.org

Birds and mammals eat the berries and spread seeds widely.

Himalayan blackberry leaflet with five leaves

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

Himalayan blackberry flower and leaves

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

Himalayan Blackberry

Rubus bifrons. R. armeniacus

Invasive Himalayan blackberry is a widespread plant that grows in neglected and natural areas throughout the Pacific Northwest. Canes have sharp thorns and form dense thickets. Take action to control Himalayan blackberry and limit its spread.

Action Recommended
Indigo bush thicket

Robert Vidéki, Doronicum Kft., Bugwood.org

Indigo bush is a thornless shrub that loses its leaves in the winter (deciduous). Stems grow roughly 12 feet tall. Plants form dense thickets.

Indigo bush leaves with leaflets

Rebekah D. Wallace, University of Georgia, Bugwood.org

Leaves have a central stem with 13–25 leaflets arranged opposite each other along the stem. The leaflets are one to two inches long, dotted, and hairy.

Indigo bush flower stems and leaves

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Indigo bush blooms in May through June. Flowers are showy and lavender-colored. They are densely arranged on erect stems. Flowers are violet to purple with yellow anthers.

Indigo bush growing by water

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Indigo bush spreads by seed and runners from the root system. It thrives along waterways and prairie draws. It also grows along forest edges and rights-of-way.

Indigo bush seed pods

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Indigo bush seeds mature in small fruit pods. Each pod contains 1–2 seeds. The pods float in water to new locations.

Indigo Bush

Amorpha fruticosa

Indigo bush is an invasive woody shrub with lavender flowers. It spreads quickly to form dense thickets, especially near water. Take action to report and control this invasive plant and prevent its spread

Action Highly Recommended
Knotweed leaves and stems

David J. Moorhead, University of Georgia, Bugwood.org

The leaves grow opposite one another along the red stems.

Knotweed leaves and flower

Barbara Tokarska-Guzik, University of Silesia, Bugwood.org

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

Knotweeds plant with many flowers

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.

Knotweed clump with many stems

Jan Samanek, Phytosanitary Administration, Bugwood.org

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

Knotweed root structure

John Cardina, The Ohio State University, Bugwood.org

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.

Knotweed stand with dead stems in dormant season

Barbara Tokarska-Guzik, University of Silesia, Bugwood.org

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


Fallopia sachalinensis , F. x bohemica , F. japonica & Persicaria wallichii

Knotweeds are a group of related, invasive plant species. They are shrub-like, broadleaf plants that die back in the winter. Knotweed plants grow 4–15 feet tall each year. They have large, oval-to-heart-shaped leaves. Take action to report and control knotweed.

Action Highly Recommended
Dense patch of of lesser celandine with flowers

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

Lesser celandine plants with roots and stems next to ruler

David L. Clement, University of Maryland, Bugwood.org

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

Yellow flower with 8 yellow sepals

Yellow flowers have yellow sepals (resemble petals).

Small, pale bulbs on stems

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.


Lesser Celandine

Ficaria verna

Lesser celandine grows 6–8 inches tall. It has dark-green leaves shaped like hearts, and yellow flowers. Lesser celandine spreads quickly. It dominates an area when left unmanaged. Take action to control this invasive weed.

Action Highly Recommended
Purple loosestrife stems with leaves and flowers

Purple loosestrife has square sided woody stems. It grows up to 10 feet tall. Mature plants may have many dozens of stems. The stems grow from a robust taproot.
Showy, abundant pink to purple flowers grow in spikes throughout summer.

Purple loosestrife leaves in whorls

Mature leaves are lance-shaped and rounded or heart-shaped at the base. Leaves are whorled and arranged opposite each other along the stem.

Purple loosestrife overtaking a wetland

Purple loosestrife spreads quickly by seed. It transforms wet areas and reduces habitat value for wildlife. It has a harmful effect on recreational areas and can clog waterways and irrigation systems.

Purple loosestrife

Lythrum salicaria

Purple loosestrife is an invasive plant. It can quickly dominate wet areas. It reduces habitat quality and clogs waterways.
Purple loosestrife is difficult to control. It spreads with seeds, stems and root fragments. Take action to control this invasive plant and prevent its spread.

Action Highly Recommended
Stand of flowering reed canarygrass

Michael Shephard, USDA Forest Service, Bugwood.org

Reed canarygrass grows up to 8 feet tall. It grows in agricultural fields, drainage ditches, roadsides, and natural areas.

Reed canarygrass leaves and stems

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Mature grass blades are ¼-⅓ inch wide and up to 14 inches long. The blades taper toward the tip. The round stems stand mostly upright, and by mid to late summer some stems may lean down to the ground. The stems are hairless.

Reed canarygrass flower heads

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Flowers are densely clustered spikes up to 12 inches long, as shown in the photo. They often have dark-green or purple streaks.

Ligule and rolled elongating leaf blade

Reed canarygrass has a papery, 1/8-1/4-inch-long flap of material (ligule). It grows from where the leaf blade connects to the stem (leaf sheath).

Reed canarygrass seeds

Reed canarygrass flower heads create thousands of seeds that easily disperse, and lead to new plants.

Reed canarygrass seedling

Seeds germinate to form new plants.

Reed canarygrass root system

Reed canarygrass forms a robust, spreading root system. It forms dense patches.

Reed Canarygrass

Phalaris arundinacea

Invasive, long-lived (perennial) grass that emerges in early spring. Grows 6 feet tall from seeds, stem fragments, and creeping rhizomes. Thrives in sites with wet soils. Forms dense stands that suppress other plants. Take action to control it.

Action Recommended
Clump of yellow flag iris leaves

John Ruter, University of Georgia, Bugwood.org

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 flower

Yellow iris (Iris pseudacorus) by Evelyn Simak - geograph.org.uk/p/6172667 is licensed under CC-by-sa/2.0.

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.

Glossy green seed pod

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

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.

Rhizome with leaves and roots

Joseph M. DiTomaso, University of California - Davis, Bugwood.org

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

Brown, flattened seeds

Steve Hurst, USDA NRCS PLANTS Database, Bugwood.org

Flattened brown seeds are about ¼ inch in diameter.

Yellow Flag Iris

Iris pseudacorus

Yellow flag iris is an invasive plant. It was introduced to the Pacific Northwest in ornamental water gardens, erosion control projects, and sewage treatment ponds. It spreads quickly, forming dense stands in shallow water and wet soil. Yellow flag iris is is toxic to livestock. Take action to control this invasive plant and prevent its spread.

Action Highly Recommended