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Rush Skeleton Weed (Chondrilla juncea)

Gallery:

Rush skeleton weed rosette
Rush skeleton weed
Rush skeleton weed flower
Rush skeleton weed in flower

Common names:

Rush skeleton weed, skeletonweed, naked weed, gum succory

Scientific Name:

Chondrilla juncea

Description:

Rush skeleton weed is a deep-rooted perennial plant in the Asteraceae (sunflower) family. It has dandelion-like rosettes and a taproot that can grow 7 feet deep. The leaves on the stem are few and very narrow and bract-like. When the plant flowers, the rosette leaves die, leaving behind just stems, which make it look skeleton-like. The yellow flowerheads are 1/2 inch wide and they grow in the leaf axils and stem tips. One of the most distinguishing features are stiff the downward pointing hairs on the lower portion of the stems. It spreads through root fragments and root buds, but also through its seeds that have white bristles that allow them to be carried by the wind, similar to the dandelion.

Life cycle:

 Perennial (Biennial in its native range)

Height of mature plants

Typically 1 to 4 feet tall, but can grow to 5 feet tall

Flower color:

yellow

Bloom time:

July – September

Look-a-likes:

Rush skeleton weed is a bit similar to dandelions and other dandelion-like plants.It has dandelion-like rosettes and a similar milky latex sap in the stems. The flower heads on rush skeleton weed have fewer “petals” than the dandelion (The “petals” are technically individual flowers. Rush skeleton weed only has 7 – 15, compared to a dandelion which has more than 70). Also. Rush skeleton weed has more branches and occasional narrow leaves on the stems.

Habitat:

Rush skeleton weeds prefers well-drained, disturbed, sandy, or rocky soils. It invades crop and grain fields, rangelands, pastures and roadsides.

Impacts:

Rush skeleton weed is a very aggressive plant, especially in rangelands and grain fields of eastern Oregon. It is banned in 9 western states. The long taproot allows it to draw water from deep under the surface, making it both drought resistant and competitive with other plants. It displaces native or desirable plants, and also has very little leaf surface, making control with herbicides very difficult. Hand pulling can be effective, but difficult because the plant can grow back from root buds, so control must be repeated for 6 to 10 years until the root reserves are depleted. One plant can produce up to 20,000 seeds.

Noxious Weed Listing:

Origin:

Northern Africa, Asia and Europe

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Control Board Profile
CABI Invasive Species Profile
NRCS Plant Guide

 

Kudzu (Pueraria montana)

Gallery:

Kudzu infestation
Kudzu leaf and flower
Kudzu flower
Kudzu seed pod
Kudzu leaf
Kudzu infestation

Common names:

Kudzu, Japanese arrowroot

Scientific Name:

Pueraria montana (syn: Pueraria montana var. lobata, Pueraria lobata)

Description:

Kudzu is a fast-growing perennial vine in the Fabaceae (pea) family. The dark green leaves alternate on the vines, have three distinct leaflets that are sometimes lobed, and are hairy on the undersides.The taproots can grow to be quite massive, and can weigh hundreds of pounds. The pea-like flowers are dark pink to purple, (sometimes red), and they are often pleasantly fragrant, like grapes. Kudzu mostly spreads vegetatively, but it also can spread by seeds that grow in brown, hairy, flattened pods.

Life cycle:

Perennial

Height of mature plants

up to 98 feet long

Flower color:

purple, red, pink

Bloom time:

July and August

Look-a-likes:

The plant grows a bit like English ivy (Hedera helix) or manroot (Marah oreganus, also called wild cucumber). However the leaves, fruits, and flowers of these plants are quite distinct. Ivy has small yellow-green flowers and dark purple berries, manroot has white flowers and green spiky cucumber-like fruits, while kudzu has purple flowers and dark brown pea-like pods.All three plants have lobed leaves, but kudzu is the only one with 3 separate leaflets.

Habitat:

Kudzu grows best in full sun, although it can also survive in shade. It prefers disturbed and well-drained soils, and can be drought tolerant once it has established.

Impacts:

Kudzu’s impacts are similar to English iy, except that it grows much more aggressively. The vines can grow up to a foot per day, and up to 30 vines can grow from a single root crown. These vines will grow over and shade out all other plants, and anything else in its path. the weight of the vines can bring down, trees, power lines, and even buildings.

Noxious Weed Listing:

Origin:

Asia and the Pacific

Links:

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

 

Fragrant Water Lily (Nymphaea odorata)

Gallery:

Fragrant water lily
Fragrant water lily with pink flowers
Fragrant water lily leaves, showing reddish underside
Fragrant water lily infestation

Common names:

Fragrant water lily, tuberous water lily, white water lily

Scientific Name:

Nymphaea odorata

Description:

Fragrant water lily is a floating perennial aquatic plant in the Nymphaeaceae (water lily) family. The leaves are rounded with a slit, have smooth margins, and the undersides are typically reddish or purplish. The leaves and flowers are attached to stalks that grow from rhizomes (underground stems) in the muddy bottom. It also has long stolons that float just below the water’s surface. The flowers are showy, with yellow centers and about 20 to 40 white (sometimes pink or pale yellow) petals. It spreads through seeds that float and rhizome fragments that break off.

Life cycle:

Perennial

Height of mature plants

The flowers and leaves float on the water’s surface, stems extend down to the mud, up to 7 feet.

Flower color:

white to pink, sometimes pale yellow

Bloom time:

June to October

Look-a-likes:

Fragrant water lily looks similar to yellow water lily, although the flowers are quite different (white/pink vs. bright yellow). Both species have floating leaves with a slit, although yellow floating heart leaves are more elliptic and have veins that extend to the edges of the leaf. The veins on fragrant water lily don’t extend to the edge and form a net-like pattern.

Habitat:

It prefers lakes, ponds, that are 3 to 7 feet deep and have mucky to silty bottoms. It can also grow in slow-moving ditches or streams, and can grow in a wide pH range.

Impacts:

Fragrant water lily can spread quickly, forming dense floating mats that cover hundreds of acres and crowd out other plants, block access and restrict passage for boats and swimmers. The floating mats can also alter water quality by increasing temperature, decreasing oxygen and contributing to algal growth. Stagnant mats can also provide mosquito breeding areas. In Washington state, drownings have occurred when swimmers were caught in the dense, tangled stems.

Noxious Weed Listing:

Origin:

Eastern North America

Links:

Washington Noxious Weed Profile
Invasive.org profile
King County Noxious Weed Profile
Global Invasive Species Database

 

Japanese butterbur (Petasites japonica)

Gallery:

Japanese butterbur
Japanese butterbur leaf
Japanese butterbur flower head
Japanese butterbur stems
Japanese butterbur stems

Common names:

fuki, giant butterbur, Japanese sweet coltsfoot, creamy butterbur

Scientific Name:

Petasites japonicus (syn. Nardosmia japonicus)

Description:

Japanese butterbur is an herbaceous, rhizomatous perennial in the Asteraceae (sunflower) family. The plant has large (4 feet wide!) kidney-shaped leaves that have woolly undersides and grow on stems that are 3 to 4 feet long. The white or cream-colored flower clumps emerge before the leaves.It needs both male and female plants to produce seeds, but the plant spread mostly through rhizomes (underground stems) that spread out in all directions.

Life cycle:

Perennial

Height of mature plants

up to 6 feet tall

Flower color:

white to pale-yellow

Bloom time:

March – April

Look-a-likes:

Japanese butterbur looks very similar to its relative, common butterbur (Petasites hybridus), which can also be invasive. Common butterbur has pink to purple flowers and the leaves are a bit smaller than Japanese butter and only grow to 1-2 feet across (rather than 3 to 4).

Habitat:

Japanese butterbur requires consistent moisture, and grows best in partially-shaded streamside or lakeside areas, meadows, and fields.

Impacts:

Japanese butterbur is often planted as an ornamental, but if the plant roots are not contained, its underground stems allow it to spread rapidly, especially in moist streamside areas. The large leaves can shade out other plants, leaving bare ground, which can lead to erosion problems.

Noxious Weed Listing:

Origin:

China, Japan, Korea

Links:

City of Portland Alien Plant Invader
Missouri Botanical Garden Weed Profile
University of Arkansas research and Extension Service weed profile

 

Yellow Flag Iris (Iris pseudocorus)

Gallery:

Yellow flag iris flower
Yellow flag iris seed pods
Yellow flag iris leaves
yellow flag iris surrounding a pond

Common names:

yellow flag iris, yellow iris, pale-yellow iris

Scientific Name:

Iris pseudocorus

Description:

Yellow flag iris is an aquatic perennial in the Iridaceae (iris) family. each stem has several showy yellow flowers, similar to other irises. The leaves are long, flat, sword-like, and grow out of the ground in a fan shape. It produces large seed capsules that are up to 4 inches long. It spreads through rhizomes and seeds that are dispersed by water. It is sometimes planted as an ornamental, and also sometimes for its ability to take up heavy metals.

Life cycle:

Perennial

Height of mature plants

Up to 4 feet tall

Flower color:

yellow

Bloom time:

April – June

Look-a-likes:

When flowering, yellow flag iris is not easily confused with other plants because it is the only yellow iris that grows in wet areas. However, when not in flower, the leaves may be confused with cattail or broad-fruited bur-reed, although the base has a flat fan shape that helps to identify it.

Habitat:

Yellow flag iris grows in shallow water, often along the shores of ponds, lakes, and slow-moving rivers, as well as in wetlands.

Impacts:

Yellow flag iris spreads rapidly in aquatic habitats, which not only excludes natives plants, but can clog waterways. It is also toxic to humans and livestock. Furthermore, this plant is very expensive and difficult to remove.

Noxious Weed Listing:

Origin:

North Africa, Great Britain, Europe, and the Mediterranean

Links:

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

 

American Pokeweed (Phytolacca americana)

Gallery:

Pressed pokeweed branch with berries
Pokeweed berries
Pokeweed plant
Pokeweed berry cluster

Common names:

pokeweed, common pokeweed, inkberry, pigeonberry, pokeberry, poke

Scientific Name:

Phytolacca americana

Description:

Pokeweed is an herbaceous perennial in the Phytolaccaceae (pokeweed) family. It has creamy-white flowers that turn to dark purple hanging clusters of berries. The leaves are smooth and spade shaped, and the stems are often pinkish or red. It has a large, fleshy taproot that it re-sprouts from every spring. It spreads mostly by berries that are eaten by birds.

Life cycle:

Perennial

Height of mature plants

up to 10 feet tall, though usually closer to 4-6 feet tall.

Flower color:

Creamy white

Bloom time:

June – July

Look-a-likes:

Pokeweed looks a bit like knotweed species, although the clusters of purple berries are very distinctive of pokeweed

Habitat:

Pokeweed can often be found in yards, pastures, forest openings or disturbed sites, and often in areas like fence lines or underneath power lines (where birds like to rest).

Impacts:

While native to the southeastern United States, pokeweed is not native to Oregon and can form dense patches that crowd out native plants. The plant is also toxic to people, livestock, and pets (although properly prepared, it can be edible). It can spread into natural areas when birds eat the berries and carry the seeds to new places. It is also difficult to control as the taproot can grow very large, up to the size of a bowling ball.

Noxious Weed Listing:

Origin:

Southeastern United States

Links:

4-County CWMA invasive plant fact sheet
East Multnomah SWCD weed profile
City of Portland BES watch species profile
Invasive.org profile

 

Gorse (Ulex europaeus)

Gallery:

Gorse branches
gorse
gorse flower
young gorse plant with spines
gorse spines
gorse infestation

Common names:

European gorse, common gorse, furze, whin

Scientific Name:

Ulex europaeus

Description:

Gorse is a stout, thorny evergreen shrub in the Fabaceae (pea) family. It has erect, spreading, angular branches that are covered in 1/2 – 2 inch spines. The flowers are yellow, fragrant and pea- shaped, and they form clusters at the end of the thorny branches. The seed pods are hairy, turn brown as they ripen, and then burst to scatter their seeds several feet away. It mostly spreads by seed, but there is also some vegetative spread. It was introduced to Bandon, Oregon in the 1890’s as a living fence.

Life cycle:

Perennial

Height of mature plants

Up to 10 feet tall

Flower color:

yellow

Bloom time:

March – May

Look-a-likes:

Gorse is sometimes compared to scotch broom or other broom species, though the thorns on gorse make it easily distinguished from these other plants that do not have thorns.

Habitat:

Gorse can be found in open, disturbed areas, as well as shady stream-sides and grasslands. It seems to do best in sandy or gravelly soils that have abundant moisture.

Impacts:

Gorse is considered to be one of the most difficult weeds to control in the world.It spreads rapidly, crowds out native plants, and its seeds stay viable in the soil for 30 years. It’s stout, thorny branches create dense stands that can impede wildlife movement and render land as nearly worthless. Furthermore, the spines contain oils, and when combined with the older dead branches, they create a serious wildfire hazard. the town of Bandon, Oregon (where gorse was first introduced to Oregon) was burned to the ground by a wildfire that was fueled by gorse infestations.

Noxious Weed Listing:

Origin:

Europe

Links:

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

 

Sulphur Cinquefoil (Potentialla recta)

Gallery:

sulphur cinquefoil plant
sulphur cinquefoil flower
Sulphur cinquefoil flower
Sulphur cinquefoil flower bracts
sulphur cinquefoil leaf
Leaves are hairy on the underside

Common names:

upright cinquefoil, rough-fruited cinquefoil, five-finger cinquefoil, yellow cinquefoil

Scientific Name:

Potentilla recta

Description:

Sulphur cinquefoil is an upright perennial in the Rosaseae (rose) family. The flowers are light yellow with five petals and a darker yellow center. The leaves have 5-7 leaflets and are rough and hairy with toothed margins. The stems are very hairy with quarter inch long hairs that stick out from the stem. It spreads through its abundant seed production.

Life cycle:

Perennial

Height of mature plants

Up to 3 feet tall

Flower color:

light yellow

Bloom time:

May – early July

Look-a-likes:

Sulphur cinquefoil looks very much like the native slender cinquefoil (Potentilla gracilis), and therefore care should be taken when identifying it. The main differences between these two are that the native slender cinquefoil has petals that are darker yellow, the leaves are a bit silvery on the underside, and the hairs are longer and perpendicular to the stem. Before flowering, the leaves are also sometimes mistaken for marijuana, though once the yellow flowers appear it is very easy to distinguish between the two.

Habitat:

Sulphur cinquefoil grows best in sunny, open habitats, so it is likely to grow in meadows, pastures, roadsides, railroads, logged areas, or abandoned lots.

Impacts:

Sulphur cinquefoil is a very aggressive noxious weed that displaces native forbs and grasses, and can even outcompete some other invasive plants. It can degrade the value of pastures and rangelands as it is unpalatable to livestock and wildlife. It is also drought tolerant and very adaptable. A single plant can live 20 years and can produce up to 5000 seeds.

Noxious Weed Listing:

Origin:

Asia and Europe

Links:

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

 

Policeman’s Helmet (Impatiens glandulifera)

Gallery:

Policeman’s helmet
A mature flowering policeman’s helmet plant
Policeman’s helmet flower
The showy flowers of policeman’s helmet
Policeman’s helmet seeds and exploded pod
A dense infestation of mature policeman’s helmet plants

Common names:

Policeman’s helmet, ornamental jewelhead, Himalayan balsam

Scientific Name:

Impatiens glandulifera

Description:

Policeman’s helmet is a showy, succulent annual in the Balsaminaceae (balsam) family. It was introduced as an ornamental plant, but it easily escapes cultivation and becomes invasive. The stems are hollow and succulent, with long leaves coming out at the nodes. The leaves have serrated margins and flowers that resemble old-fashioned English policeman’s helmets (thus, the name). A single plant can produce up to 800 seeds that are ejected up to 20 feet when ripe.

Life cycle:

Annual

Height of mature plants

Up to 8 feet

Flower color:

White to pink to purple

Bloom time:

June – August

Look-a-likes:

Policemen’s helmet looks very similar to other Impatiens species. However, the combination of the flower color (white, pink or purple vs the yellow-orange of other species), strongly serrated leaf edges, and the height make it fairly easy to distinguish.

Habitat:

Policeman’s helmet grows very well in moist natural areas, so it is often found along shady streams, ditches, and in moist forests.

Impacts:

Policeman’s helmet spreads rapidly, producing up to 800 seeds that can live a year and a half. They can form dense patches that exclude other native plants. Because they are annuals, they die in the summer, leaving behind bare soil which causes erosion and water quality problems.

Noxious Weed Listing:

Origin:

Asia (western Himalayas and India)

Links:

Oregon Noxious Weed Profile
Washington Noxious Weed Profile
Invasive.org Profile
CABI Invasive Species Compendium
Impatiens Identification Brochure

 

Purple Loosestrife (Lythrum salicaria)

Gallery:

flowers
upright flower clusters
purple loosestrife
alternate leaves
flower cluster

Common names:

Purple loosestrife, purple lythrum, spiked loosestrife

Scientific Name:

Lythrum salicaria

Description:

Purple loosestrife is an herbaceous wetland plant in the Lythraceae (loosestrife) family. It has showy, upright clusters of purple flowers. The stem is 4 to 6 sided, with leaves that are opposite and sometimes have smaller leaves coming out at the nodes. It was introduced through the ballast of ships in the 1800s and is also sometimes introduced through plant trades and sales.

Life cycle:

Perennial

Height of mature plants

Up to 10 feet tall (but usually closer to 3-5 feet tall)

Flower color:

pink to purple

Bloom time:

July to September

Look-a-likes:

Purple loosestrife can be confused with native spirea (Spirea douglasii) or native fireweed (Chamerion angustifolium). One of the obvious differences is the leaves; purple loosestrife leaves are arranged in an opposite pattern, while the look alikes have alternating leaves.

Habitat:

Purple loosestrife grows in wet areas such as wetlands, streamsides, and marshes.

Impacts:

Purple loosestrife grows vigorously in wet areas and can become dense, crowding out other vegetation. A mature plant can produce up to 2.5 million tiny seeds, which can spread by water and and birds. However, it can also reproduce by stem fragments. Areas that are heavily infested with this plant see a reduction in quality habitat for waterfowl and song birds.

Noxious Weed Listing:

Origin:

North Africa, Asia, Australia, and Europe

Links:

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

 

WeedWise Program