124 



123a. Rays yellow throughout Tickseed, Coreopsis verticillata. 



123b. Rays brown, at least at the base Tickseed, Coreopsis tinctoria. 



124a. Achenes wedge-shape, the inner ones less than 2 mm. 



wide 125. 

 124b. Achenes obovate, the inner ones more than 2 mm. wide 



Tickseed Sunflower, Bidens aristosa. 



125a. Leaf-lobes lanceolate Tickseed Sunflower, Bidens trichosperma. 

 125b. Leaf-lobes linear 



Tickseed Sunflower, Bidens trichosperma var. tenuiloba. 



126a. Outer leaf-like bracts 10 16; achenes brown 



Beggar Ticks, Bidens vulgata. 

 126b. Outer leaf-like bracts 58; achenes black 



Beggar Ticks, Bidens frondosa. 

 126c. Outer leaf-like bracts about 4 



Beggar Ticks, Bidens discoidea. 



127a. Bracts of the involucre all essentially alike in form and texture 

 (flowers in summer and autumn) (Sunflower) 179. 



127b. Bracts of the involucre in two distinct sets, differing in form 

 or consistency or both 128. 



128a. Leaves entire (3 8 dm. high; late spring and summer) 

 120b. 



128b. Leaves serrate (late summer and autumn) (Bur Mari- 

 gold) 129. 



129a. Rays large and conspicuous, 2 3 cm. long (3 10 dm. high) 



Bur Marigold, Bidens laevis* 



129b. Rays 1 cm. long or less 130. 



130a. Outer bracts leaf-like, serrate, 3 8 cm. long (4 15 dm. 

 high) Bur Marigold, Bidens comosa, 



130b. Outer bracts 12.5 cm. long (215 dm. high) 131. 



131a. Heads nodding after flowering Bur Marigold, Bidens cernua. 

 131b. Heads permanently erect Bur Marigold, Bidens connata. 



132a. Heads small, seldom more than 1 cm. wide, including the 

 rays, blooming in late summer and autumn; flowers numerous, 

 crowded in spikes, racemes, corymbs, or panicles (Goldenrod) 

 133. 



132b. Heads medium size or large, more than 1 cm. and usually 

 exceeding 2 cm. in width, including the rays 165. 



133a. Heads chiefly in clusters or short racemes in the axils of or- 

 dinary foliage leaves, or occasionally the upper compacted into 

 a leafy cluster terminating the stem 134. 



133b. Heads crowded at or near the ends of the branches at about the 

 same distance from the base of the panicle, forming a rounded 

 or flat-topped inflorescence 140. 



