Bidens comosa (A.Gray) Wiegand
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Much like no. 5 [Bidens connata Muhl.], but differing in a fairly well correlated set of characters; stem stramineous; lvs sessile or petiolate, merely toothed; outer invol bracts relatively large and leafy; disk-cors 4(5)-lobed, pale yellow or greenish-yellow; anthers included; achenes 5-10 mm, smooth except for the retrorse marginal barbels, very flat, the median nerves inconspicuous (or the outer one sometimes a little raised distally); pappus of (2)3(4) awns, the median awn(s) shorter than the lateral ones; 2n=24. Disturbed habitats, often somewhat drier than those of no. 5; widespread in c. and e. U.S. and adj. Can., s. to N.C. and Mo., and w. sporadically into the w. cordillera. Aug.-Oct. (B. acuta)