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Jewelweed (Impatiens capensis)

Gallery:

Jewelweed flower
Jewelweed flower
Jewelweed leaf
Jewelweed seeds
Jewelweed infestation

Common names:

Jewelweed, spotted touch-me-not

Scientific Name:

Impatiens capensis

Description:

Jewelweed is an annual in the Balsaminaceae (balsam) family. The flowers come in pairs, have an upper and lower lip, a curved spur, and are orange, sometimes with red spots. The leaves are alternate, up to 4.75 inches long, with rounded teeth on the margins and a pointed tip. The stems are weak and watery. Jewelweed reproduces by seeds which are ballistic and can eject 4 to 8 feet from their capsules when touched.

Life cycle:

Annual

Height of mature plants

2 – 5 feet

Flower color:

yellow – orange, sometimes with red spots

Bloom time:

August – October

Look-a-likes:

Jewelweed looks similar to other Impatiens species, however the other species that have been documented in the area all have white, purple or pink flowers.

Habitat:

Jewelweed prefers moist, semi-shady areas. It can often be found growing in riparian areas, floodplains, ditches, and in forested edges near wetlands.

Impacts:

Jewelweed can form dense stands that out-compete native plants. When this plant dies in the fall (because it is an annual), it leaves exposed soil which causes erosion and reduced water quality. Furthermore, because pollinators are attracted to this plant, it competes with native species for pollinator services, reducing seed in those native plants.

Noxious Weed Listing:

Origin:

North America (East of the Rocky Mountains)

Links:

Washington Noxious Weed Profile
Invasive.org profile
Burke Museum Plant Profile

Hairy Cat’s Ear (Hypochaeris radicata)

Gallery:

Hairy cat’s ear
Hairy cat’s ear flower head
Hairy cat’s ear flower head
Hairy cat’s ear rosette
Hairy cat’s ear
Hairy cat’s ear leaf

Common names:

Hairy cat’s ear, common cat’s ear, false dandelion, frogbit

Scientific Name:

Hypochaeris radicata

Description:

Hairy cat’s ear is a perennial plant in the Asteraceae (sunflower) family, and it is one of the most common weeds worldwide. It grows from a fibrous root system, with thick roots that are similar to a taproot. The stems have a milky juice when broken. Flowers are yellow and dandelion-like, with many green bracts under the flower head. The leaves grow in a basal rosette, are hairy, with wavy or lobed margins, and can be up to a foot long. It produces many seeds that are dispersed by the wind.

Life cycle:

Perennial

Height of mature plants

6 inches – 2 feet tall

Flower color:

yellow

Bloom time:

spring – autumn

Look-a-likes:

Hairy cat’s ear looks very similar to several other yellow-flowering plants in the Aster family, particularly smooth catsear (H. glabra), smooth hawksbeard (Crepis capillaris), fall dandelion (Leontodon autumnalis), and true dandelion (Taraxacum officinale). However, only hairy cat’s ear has the combination of rounded leaf lobes, hairy leaves, rough leaf surface, and leafless flower stalks, and these features can be used to distinguish it from other species.

Habitat:

Hairy cat’s ear can grow in both natural habitats and disturbed areas. It can tolerate a wide range of soil types, pH, and moisture. It can be found in pastures, orchards, vineyards, roadsides, lawns and gardens, parks, waste areas, and forest edges and clearings.

Impacts:

Hairy cat’s ear will invade freshly disturbed areas, and can crowd out both native species and forage plants. It can also infest seed crops, and is a nuisance in lawns.

Noxious Weed Listing:

Origin:

North Africa, West Asia, and Europe

Links:

Washington Noxious Weed Profile
UC Davis Weed Report
CABI Invasive Species Compendium

St. John’s Wort (Hypericum perforatum)

Gallery:

St. John’s wort flowers
St. John’s wort flowers
St. John’s wort
St. John’s wort infestation
St. John’s wort leaves, with tiny clear dots
St. John’s wort in seed

Common names:

St. John’s wort, common St. John’s wort, Klamathweed

Scientific Name:

Hypericum perforatum

Description:

St. John’s wort is an upright perennial herbaceous plant in the Clusiaceae (St. John’s wort/ garcinia/mangosteen) family. It is found all over the world and is often considered weedy even in its native habitat. The flowers are bright yellow with five petals with occasional small black dots. The leaves are opposite, oblong, about 1 inch long, with tiny clear dots that can be seen when held up to light. It reproduces by rhizomes, creeping stems and seeds. One plant can produce 100,000 seeds in a year.

Life cycle:

Perennial

Height of mature plants

1-2 feet

Flower color:

yellow

Bloom time:

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

Look-a-likes:

From a distance, St. John’s wort is often confused with tansy ragwort. However, tansy ragwort leaves are much larger and lobed, and the flowers have about 13 petals, whereas common St. John’s wort flowers only have five.

Habitat:

St. John’s wort grows best in full sunlight on well drained soils. It can be found growing in pastures, range lands, logged areas, meadows, roadways, and railways.

Impacts:

St. John’s wort invades pasture and range lands and is poisonous to livestock if ingested, and can also cause skin problems. It is difficult to eradicate as seeds can stay viable in the soil for 10 to 30 years.

Noxious Weed Listing:

Origin:

North Africa, Asia, and Europe

Links:

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

Shining Geranium (Geranium lucidum)

Gallery:

Shining geranium leaves and flowers
Shining geranium red stems
Shining geranium infestation

Common names:

Shining geranium, shiny geranium, shiny leaf geranium, shining crane’s bill

Scientific Name:

Geranium lucidum

Description:

Shining geranium is an annual herbaceous plant in the Geraniaceae (geranium) family. It can spread rapidly and quickly cover the ground of oak woodlands and forest openings. The pink flowers grow in pairs and have 5 separate petals with longitudinal ridges. The leaves are sparsely hairy and shiny, with 5 – 7 lobes that are again lobed. The stems have a reddish tint and grow from a weak central root. It spreads by seeds, which are forcefully ejected, and are small, abundant, and easily spread by boots, vehicles, and animals.

Life cycle:

Annual

Height of mature plants

Up to 19 inches

Flower color:

pink

Bloom time:

April to July

Look-a-likes:

Shining geranium looks quite similar to the common weed called dovefoot geranium. Dovefoot geranium’s stem are green and the leaves are not shiny. Shining geranium often grows with Robert’s geranium, which has finely divided leaves and is stinky.

Habitat:

Shining geranium can grow in a variety of light conditions. It grows well as an understory species in oak woodlands, forest openings and edges, well-shaded woodlands, grasslands, and roadsides.

Impacts:

Shining geranium emerges earlier than most native plants, and can quickly dominate the ground, preventing native plants from establishing. It can also produce multiple generations in a year, which makes control extremely difficult; after it is killed or removed, another generation of plants will quickly grow back to replace it.

Noxious Weed Listing:

Origin:

North Africa, Asia, Europe

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
Invasive.org profile
King County Noxious Weed Profile

Myrtle Spurge (Euphorbia myrsinites)

Gallery:

Myrtle spurge
Myrtle spurge
Myrtle spurge flowers and bracts
Myrtle spurge invading a field

Common names:

Myrtle spurge, donkey tail, blue spurge, creeping spurge

Scientific Name:

Euphorbia myrsinites

Description:

Myrtle spurge is a low-growing perennial plant in the Euphorbiaceae (spurge) family. It is a garden ornamental that escaped cultivation and has spread to natural areas. It grows close to the ground and exudes a toxic milky sap when any part is broken. The flowers are small, yellow, and somewhat inconspicuous, but are surrounded by more showy yellow-green heart-shaped bracts. The leaves are succulent, blue-green, and arranged in close spirals. It spreads by root fragments and small seeds which can be ejected up to 15 feet when the plant is disturbed. Seeds can survive in the soil for 8 years.

Life cycle:

Perennial

Height of mature plants

4-8 inches

Flower color:

yellow to yellowish-green

Bloom time:

March to April

Look-a-likes:

Myrtle spurge is quite distinct from other plants. The flowers and bracts of myrtle spurge look similar to other spurges. However, the succulent leaves of myrtle spurge are unique. Myrtle spurge also looks a bit similar to dalmatian toadflax. However, the flowers on toadflax are quite different, as they are two lipped, resembling snapdragons. Dalmatian toadflax is also upright.

Habitat:

Myrtle spurge generally prefers full sun and well drained soils. It can be found in gardens, fields, waste places, roadsides, natural areas, and rocky slopes

Impacts:

Myrtle spurge will invade disturbed ground and out compete native plants. Seeds can be ejected when plants are disturbed, sticking to wildlife hair and enabling transport far from the parent plant. Aside from displacing desirable native species, the plant invades playgrounds and parks in some states.When any part is broken, it excuses a milky sap which is poisonous when ingested and a severe irritant to skin and eyes.

Noxious Weed Listing:

Origin:

Western Asia, southern and eastern Europe

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
Washington State Fact Sheet
Invasive.org profile

South American Waterweed (Egeria densa)

Gallery:

South American waterweed
South American waterweed floating on the surface
submerged South American waterweed
South American waterweed flower

Common names:

South American waterweed, Brazilian elodea, common waterweed, Brazilian waterweed, dense waterweed, egeria, leafy elodea

Scientific Name:

Egeria densa

Description:

South American waterweed is a perennial aquatic plant in the Hydrocharitaceae (frogbit) family. It was introduced as a dumped aquarium plant and can be found all over western Oregon, especially along the coast. This leafy plant grows underwater in freshwater systems, and is sometimes free floating. The flowers bloom above the surface and are white with three petals. The leaves occur in whorls of 4 to 8 (mostly 4), are bright green, up to 1 inch long, and finely serrated. As only male plants have been found in the US, it doesn’t create seed; the primary reproduction method is through root and stem fragments, which easily break off and root elsewhere.

Life cycle:

Perennial

Height of mature plants

Often 1-2 feet, but it can grow up to 10 feet

Flower color:

white

Bloom time:

July and August

Look-a-likes:

South Americam waterweed looks similar to American waterweed (E. canadensis) and hydrilla (Hydrilla verticillata). However, American waterweed is much smaller and less robust, generally has only 3 leaves per whorl, and leaves are usually less than 1 cm long. Hydrilla has 5 leaves per whorl, tiny spines along the leaf margins, and also produces tubers.

Habitat:

South American waterweed is an aquatic, submerged, freshwater plant, and thus it grows in lakes, ponds, quiet streams and ditches. It is usually rooted to the bottom in depths up to 8 feet, but is also often found in floating masses.

Impacts:

South American waterweed can grow quite thick in waterways, creating obstructions to boating, fishing and swimming. The thick mats of this weed can also impede water flow, clog water pumps, shade out other aquatic plants and degrade the water quality. As an aquatic plant that also spreads by root and stem fragments, it can be quite difficult to control.

Noxious Weed Listing:

Origin:

South America

Links:

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

 

Common Teasel (Dipsacus fullonum)

Gallery:

Common teasel persistent dead flower heads
Common teasel rosettes
Common teasel leaf
Common teasel flower head
Common teasel flower head
Common teasel, bolting stem and leaves
Common teasel infestation

Common names:

Common teasel, fuller’s teasel, teasel, venuscup teasel

Scientific Name:

Dipsacus fullonum

Description:

Common teasel is a biennial plant in the Dipsacaceae (teasel) family. It is considered invasive across North and South America. The roots are stout and deeply taprooted and the stems are ridged and either hollow or pithy. Teasel grows as a rosette the first year (sometimes more than one year), and then dies after it flowers and sets seed the following year. The flowers are very dense, prickly, and can be 4 inches tall. There are distinctive spiny bracts under the flower head that curve upward and extend above the flower head. The leaves are opposite and long, with wavy margins and spines on the underside along the midvein. After it sets seed, the old flower heads can remain, containing viable seeds. It spreads through its seeds which can be transported by wildlife, soil movement, and mowing.

Life cycle:

Biennial to short-lived perennial

Height of mature plants

up to 6 or 7 feet tall

Flower color:

pink to purple (occasionally white)

Bloom time:

April to September

Look-a-likes:

Two other species of teasel are similar to common teasel: cutleaf teasel (D. laciniatus) and fuller’s teasel (D. sativus). However, both D. fullonum and D. sativus are often referred to as Fuller’s teasel as both have been used in the fulling process to make woolen cloth. Both of these similar species typically have white flowers, and the bracts underneath the flower heads are typically shorter than common teasel, whose bracts curve upward and reach above the flower head. Cutleaf teasel also has lobed leaves on the stem, while common teasel’s leaves are unlobed.

Habitat:

Common teasel grows best in sunny open habitats, and can tolerate wet to dry conditions. It is often found growing along roadsides and abandoned fields, but can also be found along the margins of wetlands, ponds, and streams. More recently it has been invading agricultural areas.

Impacts:

Common teasel can create dense stands and in open, sunny habitats, it can out-compete native grasses and agricultural plants. Large populations can be difficult to control because each plant can produce up to 34,000 seeds, and the taproots can be up to 2 feet long. It is often spread through mowing practices as old seed heads often contain viable seeds. However, small populations and young plants are easier to control.

Noxious Weed Listing:

Origin:

north Africa, west Asia, Europe

Links:

Washington Noxious Weed Profile
Invasive.org profile
CABI Invasive Species Compendium
King County Weed Profile

 

Wild Carrot (Daucus carota)

Gallery:

Wild carrot infestation
Wild carrot flower profile
Wild carrot flower, top view
Wild carrot in seed
Wild carrot
Wild carrot leaf

Common names:

wild carrot, Queen Anne’s lace, bird’s nest

Scientific Name:

Daucus carota

Description:

Wild carrot is a mostly biennial plant in the Apiaceae (carrot) family, and is also commonly referred to as Queen Anne’s Lace. Wild carrot is also the ancestor of the cultivated carrot and is widespread across the United States and Canada. It typically forms a rosette the first year, and produces flowers in the following years. Wild carrot is upright with a long taproot, a hairy stem, and finely divided leave similar to garden carrots. The white flower clusters are in umbrella shapes (umbels), 2-4 inches across, often with a few pinkish flowers in the middle. After it has gone to seed, the umbels turn upward. It is a prolific seeder, producing 1,000 to 40,000 seeds per plant, and so it can spread aggressively.

Life cycle:

Biennial or short-lived perennial

Height of mature plants

1 to 4 feet

Flower color:

white

Bloom time:

late spring through summer

Look-a-likes:

Wild carrot looks very similar to other plants in the carrot family. It may be confused with poison hemlock, which is a bigger plant with purple blotches on the stems. It can also look similar to wild chervil, which has distinct ridges on the stem. It can be distinguished from the cultivated carrot by the roots. Wild carrot has yellowish roots that are fibrous and become tough and woody. The small pinkish-purple flowers in the center, while not always present, are distinctive of wild carrot.

Habitat:

Wild carrot like sunny, dry habitats, and will thus grow in fields, weedy meadows, along railroad and roadsides, and in degraded prairies and fields.

Impacts:

Wild carrot invades open areas and can out-compete native plants because it often grows faster and larger. When it grows near cultivated carrots, there is danger of cross pollination, resulting in contaminated seed crop. Wild carrot can also harbor diseases and pests that can damage cultivated carrots. If dairy cows ingest large amounts, this plant can also taint their milk. It is difficult to control because of its deep taproot and is also resistant to mowing, since it can produce new stems from the rosettes.

Noxious Weed Listing:

Origin:

North Africa, Asia, and Europe

Links:

Washington Noxious Weed Profile
Invasive.org profile
CABI Invasive Species Compendium
UC Davis Weed Report

 

False Indigo Bush (Amorpha fruticosa)

Gallery:

False Indigo Bush along a river
False Indigo Bush flowers
False Indigo Bush in flower
False Indigo Bush
False Indigo Bush leaves

Common names:

False indigo bush, indigobush, false indigo, desert false indigo, dullleaf indigo, leadplant

Scientific Name:

Amorpha fruticosa L.

Description:

False indigo bush is a perennial shrub in the Fabaceae (pea) family. While it is native to the Great Plains of the North America, it is typically considered invasive in the Northwest, as it can form dense thickets in riparian areas. It is a fast growing legume that produces its own nitrogen, giving it advantages over other plants. Leaves are compound with 9-31 leaflets and young stems are green and hairy. Flowers are purple and showy, growing in dense upright clusters. One to two seeds grow in pods that are curved and dark brown. The seed pods float, so it easily disperses along waterways.

Life cycle:

Perennial

Height of mature plants

10 – 14 feet

Flower color:

Blue to purple

Bloom time:

July

Look-a-likes:

The leaves of false indigo bush are similar to those on a black locust tree, though false indigo bush is more of a shrub and lacks the thorns of a black locust. False indigo can also be confused with other plants in the pea family, especially licorice plants.

Habitat:

False indigo bush grows best along streams and rivers, where it can form dense thickets, but it will also grow in prairies and on sandy roadsides. It prefers partial to full sun.

Impacts:

False indigo bush forms dense thickets that out-compete other native plants. It can grow quite aggressively in riparian zones, where it can not only create a physical barrier to waterways, but can out-compete willow trees that many birds depend on. It is also very difficult and expensive to remove.

Noxious Weed Listing:

Origin:

Great Plains of North America

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
Eddmaps Profile

Welted thistle (Carduus crispus)

Gallery:

Common names:

Welted thistle, curly plumeless thistle

Scientific Name:

Carduus crispus

Description:

A large growing thistle 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.  Insect pollination is required. Reproduction is entirely by seed.  Carduus crispus closely resembles the more common C. acanthoides (plumeless thistle).

Life cycle:

Annual to biennual

Height of mature plants

1- 5 feet

Flower color:

Purple or pink to white

Bloom time:

Flowering occurs July through September.

Look-a-likes:

Similar to other thistles.  Very closely resembles the more common plumeless thistle (Carduus acanthoides)

Habitat:

irrigation ditches, field margins, waste ground, pastures, and roadsides

Impacts:

Likely contaminant in grass and alfalfa hay, reducing its quality and marketability. Welted thistle seeds may also be a contaminant in alfalfa, grain, or grass seed. Infested grasslands and pastures may see a reduction in productivity when thistle densities reach high levels. This spiny thistle would act as a deterrent to most grazing.

Noxious Weed Listing:

Origin:

Native to Europe and Asia.  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.

Present in Clackamas County:

Not known to occur

Links:

Oregon Noxious Weed Risk Assessment

Plants Database Profile: Carduus crispus

CABI Invasive Species Compendium Datasheet

 

WeedWise Program