Carduus nutans L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Biennial, 3-20 dm; lvs glabrous, or long-villous chiefly along the main veins beneath, deeply lobed, to 25 × 10 cm; heads mostly solitary and nodding at the ends of the branches, usually large, the disk (1.5-)4-8 cm wide (pressed); peduncles naked for some distance below the head; middle and outer invol bracts conspicuously broad (2-8 mm), with long, flat, spreading or reflexed, spine-pointed tip; inner bracts narrower and softer; 2n=16. Roadsides and waste places; native of Europe, now widely established in the U.S. and adj. Can., commoner westward. June-Oct. (C. thoermeri) Hybridizes with no. 2 [Carduus acanthoides L.], the hybrids partly fertile.