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Box Elder County Rush Skeleton Weed Project 2012
Figure 1. Plant in the budding stage, not yet flowering.
Photo – T. Ziehl
Box Elder County Weed Dept is working cooperatively with the Northern Utah Soil Conservation District (NUSCD) to control a new invasive weed. The major infestation can be found between northern Howell Valley and Promontory Summit. The County Weed Department and the NUSCD is currently working on mapping and treating this noxious weed.
Figure 2. Died plant stage Promontory
Photo- B. Gilson
WEED: Rush skeletonweed Chondrilla juncea L.
FAMILY: Asteraceae (Sunflower family)
Brief Plant Description: (Paraphrased from references 2 and 8).
Roots: The plant is a deep‐rooted perennial, mostly 0.4 – 1.5 m tall, appearing somewhat rushlike.
Stems: The lowermost part of the branching stem bears distinctive large, spreading to slightly
descending, reddish hairs. The upper stem is hairless. Cut surfaces of stems and leaves release
milky sap.
Leaves: The early‐deciduous basal leaves are well‐developed, runcinate‐pinnatifid, five 13 x 3.5
cm, and strongly resemble dandelion leaves. The stem leaves are linear, 2 – 10 cm long and 1‐8
mm wide, and often also deciduous, the upper often reduced to scale‐like bracts.
Flowers: The flower heads are scattered along the branches, commonly with 9‐12 yellow, strapshaped
flowers per head. The involucre of bracts is 9 – 12 mm high and thinly clothed with
white, curly, intertangled hairs.
Fruit: The body of each, pale‐brown to almost black fruit is 3 – 3.5 mm long, with five broadly
rounded longitudinal ribs separated by grooves. The tip of the fruit body bears small pointed
bumps, then 5 small scales at the base of a long, slender beak, which bear that pappus of hairlike
bristles.
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