COUPOSITAE.. 339 



Achenes 6 mm. long ; awns half as long as the achene; 

 outer bracts 6-8. 7. B. frondosa. 



Outer involucral bracts 10-16; achenes brown. 



, 8. B. vulgata. 

 Achenes linear; leaves dissected. 9. B. bipinnata. 



Rays large and conspicuous. 



Achenes cuneate or linear-cuneate. 10. B. triehosperma. 



Achenes obovate, very flat. 



Bracts of the involucre glabrous or ciliate, short. 



11. B. aristosa. 

 Outer bracts of the involucre densely hispid, much longer 

 than the inner. 12. B. involucrata. 



1. Bidens laevis (L.) B. 8. P. ' Bur-Marigold. M. p. 1000. Wet places. 



Summer and fall. 



2. Bidens cernua L. Bur-Marigold. M. p. 1001. Wet places. 'Summer 



and fall. 



3. Bidens connata Muhl. Beggar-ticks. M. p. 1001. Moist ground. 



Autumn. 



4. Bidens comosa (A. Gray) Wiegand. Tickseed. M. p. 1001. Wet soil. 



Autumn. 

 Bucks — Sellersville (Fr.). Montgomery — (P.). Lancaster — (P.). 

 Northampton — Easton, Porter (B. C). 



New Castle — With B. connata but less common. 



5. Bidens bidentoides (Nutt.) Britton. Beggar-ticks. M. p. 1001. Muddy 



shores. Autumn. , . 



Philadelphia— Philadelphia, Mart. (B. C), common (Me.). Bucks — 

 Bristol (Fr.). Delaware— Tinieum (Fu.). 



Burlington — Delair (Ja.). Camden '— Camden (He.). Gloucester — 

 Washington Park (Ja.), Bridgeport (W. Tr.), Westville (Wn.). Salem— 

 Shores of Delaware (C). 



New Castle— Wilmington (Pr.), Delaware Eiver, Canby. 



6. Bidens discoidea (T. & G.) Britton. Beggar-ticks. M. p. 1002. Wet 



banks and swamps. Summer. 

 Bucks— Tullytown (Cr.), Bristol (Fr.). Delaware— Tinieum (Fu.). 

 Northampton — Easton (Ca.). 



Camden— Shores of Delaware (C). Salem — Tidal banks (C). 

 New Castle— Townsend, Canby; Delaware River, Canby. 



7. Bidens frondosa L. Common Beggar-ticks, Stick-tight. ' M. p. 1002. 



Moist waste places. Summer and fall. 



8. Bidens vulgata Greene. Beggar-ticks. M. p. 1002. Moist soil. Sum- 



mer and fall. 



9. Bidens bipjnnata L. Spanish Needles. M. p. 1002. Damp soil. Sum- 



mer and fall, 



10. Bidens trichosperma (Michx.) Britton. Tickseed Sunflower. M. p. 



1002. Swamps near the coast. Autumn. 

 Philadelphia — West Philadelphia (Mac), Frankford (Wn.). Bucks— 

 Bristol (Fr.). Delaware— Tinieum (Fu.) (B. Sm.). Chester— (W. Tr.), 

 New Jersey — Frequent. 

 New Castle— Frequent. 



