phyllaries ovate or ovate-lanceolate, shorter (finally 5-7 mm. long); ray flowers 

 absent or if present minute, the golden-yellow ray 2-3.5 mm. long, cuneate- 

 obovate, commonly 2- or 3-denticulate; achenes flat, narrowly cuneate, blackish, 

 subglabrous or pilose-hispid, on each face strongly 1-nerved, the body 6—10 mm. 

 long; pappus awns 2, retrorsely barbed, 3-4.5 mm. long. 



In moist woods, swampy meadows, alluvial thickets, borders of streams, ponds, 

 sloughs, swamps, ditches, fields, waste ground, in Okla. (Mcintosh, Comanche, 

 Delaware, McCurtain and Cherokee cos.) and in e. half of Tex., recently reported 

 from Hemphill Co. in the Panhandle, N.M. (Bernalillo and San Juan cos.) and 

 Ariz. (Greenlee and Yavapai cos.), spring-early summer; e. Can., most of the U.S. 



10. Bidens leptocephala Sherff^. Fig. 772. 



Annual herb, 1-5 dm. tall, branched; leaves petiolate (petioles 3-40 mm. long), 

 including the petioles 2-10 cm. long, 15-55 mm. broad, bipinnate, minutely 

 ciliate, hispid or glabrate, the segments sometimes linear or sometimes ovate; 

 peduncles 2-8 cm. long; heads 4—8 mm. broad, 3-5 mm. high (in fruit to 15 mm. 

 high); involucre subglabrous at the base; outer phyllaries 4 to 6, linear, ciliate, 

 10-25 mm. long, inner ones half again as long, lanceolate, glabrous or at the 

 apex pubescent; rays occasionally absent, usually 3, only 2.5 mm. long and 1.2 

 mm. broad, whitish, entire or bidentate; achenes 5 to 9, rarely to 13, subquad- 

 rangulate, linear, the inner ones blackish, 9-14 mm. long, some of the outer ones 

 sometimes shorter and browner; pappus awns 1-3 mm. long, retrorsely barbed. 



Frequent in moist canyons, along streams, in the Tex. Trans-Pecos mts., N.M. 

 (Grant and Guadalupe cos.) and Ariz. (Cochise, Santa Cruz and Mohave cos.), 

 summer; Chih., Tex., N.M., Ariz, and Baja Calif. 



11. Bidens pilosa L. Fig. 770. 



Annual herb, erect, branched, 3-18 dm. tall; petioles 10-65 mm. long; leaves 

 including petioles 5-20 cm. long, membranous, on the margins ciliate and serrate, 

 on each surface subglabrous or scatteringly pilose with unequal and appressed 

 hairs or sometimes densely tomentose-pilose, the lowermost often simple, ovate, 

 apically acute, the midstem leaves 3- to 5- (or even 7-) partite, the uppermost 

 leaves simple and lanceolate; heads 7-8 mm. broad, 5-7 mm. high (at anthesis); 

 peduncles 1-9 cm. long; involucre basally hispid; outer phyllaries 7 to 9, linear 

 or linear-spatulate, indurate-apiculate, ciliate, 4-5 mm. long, shorter than the 

 lanceolate inner phyllaries; rays commonly absent or when present minute (2-3 

 mm. long) or well-developed (to 15 mm. long), white or pale-yellowish-white; 

 achenes linear, straight or the marginal ones incurved, obcompressed-quadrangulate 

 or flattish, glabrous below, tuberculate-strigose above, 4-16 mm. long, the inner 

 ones longer than the outer; pappus awns 2 or 3 (rarely to 5), yellowish, retrorsely 

 barbed. 



Infrequently (probably repeatedly) waifed along sloughs and in resacas in 

 extreme s.e. and Trans-Pecos Tex. and Ariz. (Cochise, Santa Cruz and Pima cos.), 

 summer-fall; an exceedingly common weed of disturbed moist soil in all the 

 warmer parts of the world, not hardy in the temp, parts but repeatedly introd. 



12. Bidens tenuisecta Gray. 



Stems 2-8 dm. tall, more or less branched especially above, glabrous or sparsely 

 hairy; leaves at least basal petioled, usually 2- to 3-pinnately dissected into 

 narrowly linear ultimate segments 0.5-2.5 mm. wide; heads about 6-10 mm. high 

 and 4-10 mm. wide; outer phyllaries 6 to 12, about 5-7 mm. long, linear, inner 

 phyllaries subequal; rays inconspicuous, 4-6 mm. long, yellow or lacking; achenes 

 linear but tapering to apex, inner 8-15 mm. long, outer shorter and broader, 

 different; pappus of 2 or rarely 3 retrorsely barbed awns 1.5-3 mm. long, at 

 least on inner achenes. 



1671 



