Weed class: B
Year Listed: 1988
Native to: Europe, Asia and Northern Africa
Is this Weed Toxic?:
not known to be
Why Is It a Noxious Weed?
Rush skeletonweed is a threat to irrigated lands, wheat areas and rangelands. Rangeland infestations displace native and beneficial forage species grazed by livestock and wildlife.
How would I identify it?
It is a perennial ranging in size from 1 to 5 feet tall. Its long slender taproot can grow up to 7 feet deep. Plants begin as a basal rosette of leaves and then grow 1 to 6 branching flowering stems. Plants will exude a latex sap from injured surfaces.
Flowerheads 1/2 inch in diameter and grow in leaf axils and stem tips, single or in clusters. Flowerheads have usually 11 (7 – 15) yellow ray flowers. Green bracts at base of flower head in a single row followed by a single row of smaller bracts.
Basal leaves are lobed with lobes pointing back towards the leaf base. Leaves on branching stems are few, narrow and may have entire (smooth) edges.
Stem bases have coarse, downward pointing brown hairs and are hairless toward the tips. Stems are highly branched and have few leaves.
Fruit Seed Description
Seeds 0.1 inch (3 mm) with ribbed surface and white bristles (pappus) on one end that aid with wind dispersal.
Where does it grow?
Rush skeletonweed is found in pastures, rangeland, cropland, roadsides, open and disturbed areas. Please click here to see a county level distribution map of rush skeletonweed in Washington.
How Does it Reproduce?
Plants spread by seed with each mature plant producing between 1,500 and 20,000 seeds. It also spreads by shoot buds found along lateral roots and from shoot buds found near the top of the main root. It also grows from root fragments in the soil.
How Do I Control It?
General Control Strategy
Research found that an integrated approach, using both plant competition and biological control agents, often results in better control then either method used separately. Herbicide control may vary depending on the biotype of rush skeletonweed.
Hand-pulling can work for small infestations. Areas must be controlled 2 to 3 times per year for 6 to 10 years to remove seedlings and re-sprouting roots. Removal of deep tap roots is easiest when soils are damp. Mowing plants repeatedly may reduce plants' biomass and seed production but may not provide eradication.
Using beneficial forage species for competition will not suppress the dominance of rush skeletonweed. Continual grazing decreases populations while rotated grazing increases populations.
The gall midge (Cystiphora schmidti) was introduced to California in 1975 and is established throughout the Pacific Northwest. The gall midge impacts the rosette and flowering stems of all biotypes in this region. Affected stands are often a noticeable purple to reddish color. The rust fungus (Puccinia chondrillina) was introduced to Washington in 1978. Two biotypes, the early-flowering biotype in Washington and Idaho and the late-flowering biotype in Oregon, are resistant to this rust. A gall mite (Eriophyes chondrillae) was introduced to Washington in 1979, and it is considered the most effective biological control agent available to date. This mite is effective against all biotypes of rush skeletonweed. The visible impacts to flowering buds are leaf-like galls, up to 2 in diameter, which can reduce or prevent seed production.
For More Information
See our Written Findings for more information about rush skeletonweed (Chondrilla juncea).
Thurston County NWCB Fact Sheet on rush skeletonweed
Franklin County NWCB Fact Sheet on rush skeletonweed
Asotin County NWCB Fact Sheet on rush skeletonweed
Pierce County NWCB Fact Sheet on rush skeletonweed
Stevens County NWCB Fact Sheet on rush skeletonweed
Control Options for rush skeletonweed from Lincoln County NWCB