Genus 67.] 



THISTLE FAMILY. 



439 



8. Bidens bipinnata L,. Spanish 

 Needles. (Fig. 3945-) 



Bidens bipinnata L. Sp. PI. 832. 1753. 



Annual; stem quadrangular, erect, freely 

 branched, rather slender, i-5 high. Leaves thin, 

 acuminate, petioled, 1-3-pinnately dissected into 

 ovate or oblong, toothed or lobed segments, the 

 lower often S / long; heads usually numerous, long- 

 peduncled, 2 // -4 // broad; involucre narrow, its 

 outer bracts linear, ascending, nearly as long as the 

 broader erect inner ones; rays 3-4, yellow, short, 

 sometimes none; achenes linear, 4-angled, slightly 

 pubescent, narrowed upward into a beak, 5" -9" 

 long, the outer ones commonly shorter and thicker 

 than the inner; pappus of 2-4 (usually 4), down- 

 wardly barbed, slightly spreading awns, much 

 shorter than the achene. 



In various situations, often a weed in cultivated 

 fields, Rhode Island to Florida, west to Ohio, Nebraska 

 and Arizona. Also in Mexico and tropical America 

 and introduced as a weed into southern Europe and Asia 



July-Oct. 



g. Bidens coronata (L,.) Fisch. Southern 

 Tickseed-Sunflower. (Fig. 3946.) 



Coreopsis coronata L. Sp. PI. Ed. 2, 1281. 1763. 

 Coreopsis aurea Ait. Hort. Kew. 3: 252. 1789. 

 Bidens coronata Fisch.; Steudel, Norn. Ed. 2, 202. 1840. 



Annual, glabrous or nearly so throughout; stem 

 branched, i-3 high. Lower leaves petioled, 3'- 

 5' long, 3-divided, the terminal segment lanceolate, 

 acute or acuminate, serrate, much larger than the 

 serrate or entire lateral ones; upper leaves much 

 smaller, 3-parted, 3-lobed or undivided, sessile or 

 short-petioled, entire or serrate; heads numerous, 

 slender-peduncled, \'-i' broad; involucre hemi- 

 spheric, its outer bracts linear-oblong, obtuse, equal- 

 ling or slightly exceeding the broader inner ones; 

 rays 6-10, obtuse; achenes broadly cuneate, slightly 

 pubescent, \"-i" long; pappus of 2 chaffy diver- 

 gent somewhat laciniate teeth, rarely with 2 shorter 

 intermediate ones. 



In wet places, Virginia (according to Gray), to Florida 

 and Alabama. July-Sept. 



10. Bidens trichosperma (Michx.) Brit- 

 ton. Tall Tickseed-Sunflower. (Fig. 3947.) 



C. trichosperma Michx. Fl. Bor. Am. 2: 139. 1803. 



B. trichosperma Britton, B ull. Torr. Club, 20: 281. 1893. 



Annual or biennial, glabrous; stem tall, obscurely 

 quadrangular, much branched, 2-5 high. Lower 

 leaves petioled, 4 / -8 / long, pinnately divided into 

 5-7 lanceolate acuminate, sharply serrate, incised 

 or nearly entire, sessile or short-stalked segments; 

 upper leaves sessile or nearly so, 3-lobed, 3-divided, 

 or entire and linear-lanceolate; heads numerous, 

 i^ / -2^ / broad, long-peduncled; involucre hemi- 

 spheric, its outer bracts linear or spatulate, some- 

 times ciliate, about the length of the broader inner 

 ones; rays 6-19, obtuse, golden yellow, 7 // -i2 // long; 

 achenes oblong-cuneate, hispid-pubescent and cili- 

 ate, 2)"-\" long; pappus of 2 short erect or diver- 

 gent, upwardly hispid teeth or short awns. 



In swamps and wet meadows, Massachusetts to Geor- 

 gia, Illinois and Kentucky. Aug.-Oct. 



Bidens trichosperma tenuiloba (A. Gray) Britton, Bull. Torr. Club, 20: 281. 

 Coreopsis trichosperma var. tenuiloba A. Gray, Syn. Fl. 1: Part 2, 295. 18S4. 



Segments of the leaves linear-lanceolate, serrate or entire ; achenes sometimes smaller. In bogs, 

 Illinois, Indiana, Minnesota and southern Ontario. A similar form occurs in southern New Jersey. 



