Origin: Introduced
Voucher:WS
Notes: FNA19: "A population of Centaurea trichocephala M. Bieberstein ex Willdenow (featherhead or hairy-head knapweed) was found in the late 1970s in a degraded pasture in eastern Washington (B. F. Roché and C. T. Roché 1991). A weed-control program was instituted, and the plants were successfully eradicated. Although it is apparently not established anywhere in North America, C. trichocephala is listed as a noxious weed in Oregon. These plants resemble C. phrygia in having elongate, pectinate-fringed phyllary appendages. In C. trichocephala the linear-filiform, featherlike appendages are much narrower than the phyllary bodies. Plants of the species spread by horizontal roots. According to Roché and Roché, C. trichocephala is apparently self-sterile; the Oregon plants spread clonally and formed no seeds."
Literature:
» Wagenitz, G. 1975. Centaurea L., pp. 465-585, in Flora of Turkey and the East Aegean Islands, vol. 5, P.H. Davis, ed. Edinburgh University Press, Edinburgh.
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