Bidens. COMPOSITE. 297 



or even 6 lines long, in the same plant either smooth with sparing bristles, or the outer becoming 

 tuberculose and rough. 



B. leucantha, WILLD. Leaves of rather firm texture, some undivided and ovate; these 

 and tin; ,'i or occasionally 5 ovate or oblong-ovate divisions evenly serrate, more or less lin- 

 eately veiny : heads corymbosely paniculate on rather short peduncles : rays obuvate, bright 

 white, 5 to 8 lines long, rather showy. Spec. iii. 1719; Torr. & Gray, 1. c. B.'striatrt, 

 Swi-.-t, Hrit. Fl. Card. t. 2.37; Hook. Bot. Mag. t. 3155. Corn >/,*;* /, ,,,;i,itl,> ma, L. Amcen! 

 Acad. iv. 291. C. leucantha, L. Spec. ed. 2, ii. 1282; Desc. Fl. Ant. t. 583. C. coroxufu, 

 L. 1. c. 1281, as to syn. Plum. t. 53, f. 2. Common in S. Florida. (W. Ind., Mex.) 



B. pilosa, L. Stem sometimes tall, usually weak: leaves thin; leaflets 3 to 5, irregularly 

 serrate, sometimes incised, or the lower divisions occasionally 3-lobed : heads fewer and 

 scattered : rays, commonly none, at most inconspicuous and yellowish-white. Spec. ii. 832 

 (but the cited figure, Dill. Elth. t. 43, probably belongs to B. frondosa] ; Willd. I. c. Core- 

 opsis alba, L. Spec. ii. 908 (Herm. Parad. t. 124 '? excl. syn. Pluk.). Bidens Culifornica, DC. 

 Prodr. v. 599 ; Torr. & Gray, Fl. ii. 354. Variable, and the slender forms in warm coun- 

 tries seeming to pass into B. hifiintiuta. S. California and Arizona, introduced 1 (Mex. to 

 Chili, W. lud., and all tropics.) 



* -* Leaves all once to thrice 3-5-nately parted or divided into oblong or linear ultimate lobes : 

 root in ours annual. 



f Heads narrow: rays inconspicuous and yellowish or none: akenes long and slender, at least 

 the central ones much surpassing the involucre. 



-H- Lobes of the thin leaves from oblong to lanceolate: heads slender-peduncled. 



B. bipinnata, L. (SPANISH NEEDLES.) Primary and secondary divisions of the leaves 

 rather ovate or deltoid-lanceolate in circumscription, and the lobes mostly acute :' akenes all 

 slender, the inner ones 5 to 9 lines long, outermost moderately shorter and thicker : awns 

 3 or 4, sometimes only 2. Spec. ii. 832 ; Michx. ii. 135 ; Torr. & Gray, 1. c. Damp 

 thickets and waste ground ; a common and disagreeable weed, New England to Florida and 

 Arizona. (Trop. Am., c.) 



B. Bigelovii, GRAY. Lobes of the leaves linear-oblong, mostly obtuse : innermost akenes 

 5 or 6 lines long, 2-3-awned ; outermost of half that length or less, stouter, 2-corniculate, or 

 with a pair of short awns, or even witb^none. Bot. Mex. Bound. 91. B. tenni*la, in part, 

 Gray, PI. Wright, i. 109. S. W. Texas to S. Arizona, first coll. by Wriyht and Biytl<i: 



H- -H- Lobes of the leaves linear. 



B. tentlisecta, GRAY. A foot or two high, branched from the base, sparsely hirsute or 

 glabrous: leaves 2-3-ternately or pinnately dissected into narrow linear lobes (of a -line or 

 more in width): heads on naked rather long and stout peduncles, many-flowered, 4 or 5 

 lines high in flower: involucre hirsute, especially at base: akeues glabrous, 2-awned ; inner 

 5 lines long, with tapering summit; outermost 3 lines long, stouter and with broad summit 

 and usually short awns: rays yellow, mostlv surpassing the disk. PI. Feiidl. 86. Along 

 water-courses, Colorado, New Mexico, and Arizona; first coll. by Fendler. 



B. Lemmoni. A foot or less high, slender, with short branches, smooth and glabrous : 

 leaves twice ternately parted into entire obtuse rather broadly linear lobes (a line or two 

 wide) ; the uppermost simply 3-5-parted, subtending the mostly sessile 5-9-flownvd cylin- 

 draceous and glabrous heads: akenes nearly of the preceding, but the outer nearly like the 

 inner: rays apparently none. S. Arizona, in Apache Pass, Lcinmon. 



B. heterosperma, GRAY. Slender, glabrous, paniculately much branched : leaves once 

 or twice ternately parted into filiform-linear (half-line wide) lobes: heads on slender pe- 

 duncles, few-flowered, in flower barely 3 lines long : rays apparently none : akenes 2-3-awued, 

 smooth ; the inner 4 or 5 lines long outermost only 2 lines long and their short awns cadu- 

 cous. PL Wright, ii. 90. S. Arizona: raised from seed coll. by Wriyht (thought to come 

 from New Mexico): rediscovered in Apache Pass by Lninnon. 



-t -t Heads broader, many-flowered, and with comparatively large deep yellow rays : akenes all 

 short, hardly surpassing the involucre. 



B. procera, DON. Erect and tall from an annual or biennial root, glabrous : leaves twice 

 or thrice parted into narrow linear lobes (mostly of an inch or more in length and less than 

 a line wide) : heads corymbosely paniculate : outer involucre small and inconspicuous, 



