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cuneate, 8-10 mm. long, their sides and the 2 slender pappus-awns (rarely with I 

 a short intiermediate awns) upwardly barbed or hispid. Muddy shores, Penn., 

 N. J., Del. and Md. Aug.-Oct. 



8. Bidens discoidea (T. & G.) Britton. Small Beggar-ticks. (I. F. f. 3943.) 

 Annual, glabrous, slender, branching, erect, 5-18 dm. high. Leaves membranous, 

 very slender-petioled, all the lower ones divided into 3 lanceolate or oblong-lance- 

 olate, dentate, acuminate segments which are 2-7 cm. long ; uppermost leaves 

 commonly rhombic-lanceolate and undivided; heads usually numerous, slender- 

 peduncled. 5-10 mm. broad; involucre broadly campanulate or hemispheric, its outer 

 bracts mostly foliaceous and obtuse, usually much surpassing the inner ones; rays 

 apparently always wanting ; achenes flat, narrowly cuneate, upwardly strigose, abcut 

 4 mm. long; pappus of 2 short, upwardly hispid, rarely downwardly barbed awns. 

 In swamps and wet places, Conn, to Va., Ohio, Mich., La. and Tex. July-Sept. 



9. Bidens frondosa L. Black Beggar-ticks. Annual ; stem erect, 

 branched, sparingly pubescent or glabrous, 5-10 dm. high. Leaves slender- 

 petioled, pinnately 3-5 -divided or the uppermost undivided, the segments lanceo- 

 late or oblong-lanceolate, sharply serrate, acuminate at the apex, narrowed at the 

 base, usually slightly pubescent beneath, stalked, 5-10 cm. long, 1-2 cm. wide; 

 heads usually numerous, slender-peduncled, 9-15 mm. broad; involucre campan- 

 ulate, becoming hemispheric, its outer bracts foliaceous, often exceeding the oblong 

 inner ones; achenes flat, cuneate, nearly black, the margins upwardly hairy; the 

 two slender awns downwardly barbed, or sometimes upwardly hispid. In moist 

 soil, often a weed in fields, N. B. to Fla., Neb. and Tex. July-Oct. 



10. Bidens vulgata Greene. Tall Beggar-ticks. (I. F. f. 3944, as B. fron- 

 dosa.) Taller, sometimes 3 m. high, glabrous or nearly so. Leaves pinnately 3-5- 

 divided, the veins straight and prominent; heads larger, 1.5-2.5 cm. broad, stout- 

 peduncled; outer involucral bracts linear to linear-spatulate, ciliate, the inner mostly 

 ovate or narrowly triangular, pubescent at the apex; ray-flowers usually present 

 pale yellow; achenes very flat, 7-9 mm. long, 4-5 mm. wide, brown or greenish 

 brown; the margins downwardly barbed above, upwardly hairy below; awns 2, half 

 as long as the achene or more, downwardly barbed. In moist soil, Ont. to N. Car., 

 Br. Col., Mo. and Cal. 



Bidens vulgata pubcrula (Wiegand) Greene. Crisp-pubescent above, especially on 

 the involucre; inner bracts pubescent on the back. Wis. to Saskatch., Iowa, Neb. and 

 Mo. 



11. Bidens bipinnata L. Spanish Needles. (I. F. f. 3945.) Annual; stem 

 quadrangular, erect, freely branched, rather slender, 3-15 dm. high. Leaves thin, 

 acuminate, petioled, 1-3-pinnately dissected into ovate or oblong, toothed or lobed 

 segments; lower leaves often 2 cm. long; heads usually numerous, long-peduncled, 

 4-8 mm. 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, 10 18 

 mm. long, the outer ones commonly shorter and thicker than the inner; pappus of 

 2-4 (usually 4), downwardly barbed, slightly spreading awns, much shorter than 

 tin- achene. In various situations, often a weed in cultivated fields, R. I. to Fla., 

 west to Ohio. Neb. and Ariz. Also in Mex, and tropical Am., and introduced as a 

 weed into southern Europe and Asia. July-Oct. 



12. Bidens coronata (L.) Fisch. SOUTHERN TlCKSEED-SUNFLOWER. (I. F. 

 f. 3946.) Annual, glabrous or nearly so throughout; stem branched, 3-9 dm. high. 

 Lower leaves petioled, 7-12 cm. 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 • ; head- numerous, slender-peduncled, 3 5 cm. broad; involucre 

 hemispheric, its outer bracts linear-oblong, obtuse, equalling or slightly exceeding 

 the broader inner ones; rays 6-10. obtuse; achenes broadly cuneate, 2-4 mm. long 

 pappus of 2 chaffy, divergent, somewhat laciniate teeth, rarely with 2 shorter inter- 

 mediate one-. In Wet places, Ya. to Fla. and Ala. July S< pt. 



13. Bidens trichosperma (Michx.) Britton. Tall Tickseed-SunfloweJL 

 (I. F. f. 3947.) Annual or biennial, glabrous; stem tall, obscurely quad ranguldl 

 much branched, 6-15 dm. high. Lower leaves petioled, 1-2 cm. long, pinnately 





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