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Biological controls for PLUMELESS THISTLE coming soon.

 

 

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Plumeless Thistle

PLUMELESS THISTLE-Carduus acanthoides L.

Asteraceae-(Sunflower family)

Plumeless thistle is a winter annual or biennial herb, from a stout fleshy tap-root, rarely flowering the first year.  Stems grow from 1 to 4 feet tall; they are freely branched above and covered with spiny wings 1/4 to 3/4 inch wide extending up to the flowering heads.  Basal rosette leaves are usually 4 to 8 inches long with spinose lobes.  Stem leaves alternate, sessile and blending into the stem.  Peduncles usually spiny-winged up to the base of the flowering heads; heads solitary at the ends of branches or in clusters of 2 to 5.  Involucral bracts narrowly lanceolate, sparsely to densely hairy.  Corolla mostly purple, rarely white or yellowish. 

This native of Eurasia is infrequent to locally abundant in pastures, stream valleys, fields and roadsides.  It is frequently found in Idaho, Colorado, and Wyoming and has the potential of becoming a widespread noxious weed.  Flowering occurs from May to July.

(Courtesy of Weeds of the West)

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