132 



FIELD COLUMBIAN MUSEUM BOTANY, VOL. III. 



dular, hairy at the base, bracts in 2 series, loose and spreading, 

 outer longer, linear, inner narrowly lanceolate, puberulent at the acute 

 tip. Ray corollas yellow, incon- 

 spicuous, ligule bidentate, 2-2.5 

 mm. long, erect; disk corollas 

 nerved, 5 lobed. Receptacle sub- 

 convex; scales linear, a little shorter 

 than the disk flowers. Achenes 

 brown or light olive, .8-1 x 10-17 

 mm., linear-oblong, slightly taper- 

 ing to the summit, the inner erect 

 or curved at the summit, the 

 outer sublunate; in section irregu- 

 lar lozenge-shaped; impressed stri- 

 ate, the surface minutely papil- 

 late; inner achenes glabrate below, 

 sparsely hispid above, the outer 

 densely hispid; at the apex and 

 often at the base of the achenes is a tuft of delicate gland tipped white 

 hairs; awns 4, middle one erect, the others divergent or deflexed, 

 retrorsely barbed, 2-3 mm. long. 



Hab. Izamal, Gaumer 2498, 2499, 2504. 



Bidens tereticaulis DC. Prod., 5:598. 



A climbing or reclining herb with terete, glabrous stem and 

 branches, and opposite, slender-petioled, 3-5 parted, acuminate, 

 serrate, nearly glabrous leaves. Inflorescence a terminal panicle of 

 opposite, divaricate, few-flowered corymbs, branchlets and peduncles 

 slender, terete, little striate, glabrous. Heads (in flower) 9 mm. high, 

 25-27 mm. broad; ray flowers 5, disk flowers numerous. Involucre 

 sparsely pubescent at the base, bracts in 2-3 series, loose and spread- 

 ing, acute, outer shorter, linear; 

 inner linear-lanceolate. Ray 

 corollas yellow, tube short, ligule 

 elliptic, entire, 8-10 mm. long, 

 spreading; disk corollas nerved, 

 5 lobed. Receptacle plane ; scales 

 linear-oblong, bearded at the 

 obtuse apex, as long as the disk 

 flowers. Achenes dark brown, 

 i-i.i x 10-13 mm., linear-oblong, 

 slightly tapering to the summit, 

 the inner erect or nearly so, the 

 outer slightly lunate; in section 

 lozenge-shape; impressed stri- 

 ate, the surface papillate-rugose, 

 the margins tuberculate-hirsute, 

 otherwise glabrous; awns 2, sub- 

 erect in the inner, diverging or subdeflexed in the outer achenes, slen- 

 der, retrorsely barbed, 3-3.5 mm. long. 



