THE GENERAL, CHARACTERS OF SEEDS 489 



Spanish Needles (Bidens bipinnata L.). 



Achenes exclusive of awns one-half to three-fifths in. long, linear, 

 4-angled, slightly pubescent; pappus consisting of usually 4 diver- 

 gent downwardly barbed awns, lighter in color than the achene; 

 base of seed with a lightish ringed border and a small depression. 



Fig. 364A Fig. 364B 



Fig. 364. A. Seeds of Spanish Needles, Pitchforks, or Bootjacks, a, Spanish 



Needle (Bidens frondosa), b, Bidens bipinnata.. 



B. Bidens discoidea. 



(Drawings by Charlotte M. King.) 



Small Stick-tight (Bidens discoidea (T. & G.) Britton). 



Achenes small, flat, narrowly acuminate, upwardly strigose; 

 pappus of upwardly hispid, rarely downwardly barbed awns. 



Beggar-ticks (Bidens frondosa L.). 



Achenes flattened, oval or obovate, three-tenths to two-fifths 

 inch exclusive of the awns; slightly eiliate on the margins (see 

 figure) ; awns generally diverging, downwardly barbed ; corolla 

 tube, whitish, with small opening in the center; basal portion of 

 achene with a prominent depression with a light border. The 

 achenial hairs, according to Miss Mary A. Nichols and Mr. Fracker, 

 are duplex. In B. cernua they are simple. The related species 

 (B. aristosa) formerly called Coreopsis has duplex hairs, although 

 some hairs are simple. 



