Centaurea repens L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Coarse, bushy-branched, colonial perennial from deep- seated creeping roots, 4–8 dm, finely arachnoid-tomentose, becoming glabrate; lvs rather small, the lower cauline ones to 15 × 4 cm and often few-toothed, the others numerous, smaller, entire or few-toothed; heads numerous, terminating the branches; invol pale, 9–15 mm, the middle and outer bracts broad, striate, glabrous, with large, broadly rounded, subentire hyaline tip, the inner bracts narrower, tapering to a plumose- hairy tip; fls purple, the marginal ones not enlarged; larger pappus-bristles subplumose above, 6–11 mm; achenes basilaterally attached; 2n=26. Fields, roadsides, and waste places; native of Asia, now widely established in w. U.S. and occasional in our range. June–Sept. (C. picris; Acroptilon r.)