COMPOSITE. (composite FAMILY.) 219 



29. PTEROCAULON, Ell. 



Heads and flowers chiefly as in Pluchea. Scales of the involucre lanceolate, 

 imbricated in several rows, caducous. Receptacle minutely hairy. Achenia 

 angled, pubescent. Pappus of numerous equal capillary bristles, longer than 

 the involucre. — Perennial herbs. Leaves lanceolate, densely tomentose and 

 hoary beneath, the margins broadly decurrent on the stem. Heads compactly 

 spiked. 



1. P. pycnostachyum, Ell. Stem rarely branched, 1°- 2° high; leaves 

 wavy, smooth above ; spike thick, woolly ; flowers white. — Damp pine barrens, 

 Florida to North Carolina. Juno and July. 



Tribe IV. SENECIONIDE^. Heads discoid or radiate: branches of the 

 stifle, in the perfect flowers, linear, convex externally, hairy or brush-shaped at the 

 apex, and truncate, or produced into a conical or hispid appendage ; the stiymatic 

 lines terminating at the appendage, not confluent. 



.30. POLYMNIA, L. 



Heads many-flowered ; the rays pistillate, in a single row ; those of the disk 

 tubular, 5-toothed, sterile. Scales of the involucre in two rows ; the outer leafy, 

 spreading ; the inner smaller, membranaceous, clasping the obovoid fertile ache- 

 nia. Receptacle chaft'y. Pappus none. — Coarse branching perennial herbs, 

 with angular or lobed leaves, and heads of yellow flowers in corymbose panicles. 



1. P. Canadensis, L. Viscid-pubescent ; lowest leaves opposite, peti- 

 oled, pinnatifid ; the upper alternate, angled or lobed ; outer scales of the invo- 

 lucre acuminate, hairy and viscid ; rays shorter than the involucre. — Mountains 

 of North Carolina. July and August. — Stem 2° - 5° high. Heads small. 

 Rays pale yellow. 



2. P. Uvedalia, L. Stem smooth, or rough-pubescent ; leaves broadly 

 ovate, 3 - 5-lobed, coarsely toothed, rough above, pubescent beneath, abruptly 

 contracted into a sinuate-winged petiole ; outer scales of the involucre ciliate, 

 obtuse; rays much longer than the involucre. — Rich soil, Florida, and north- 

 ward. July and August. — Stem 3° - 6° high. Rays bright yellow. 



31. CHRYSOGONUM, L. 



Heads many-flowered ; the rays 5, pistillate. Disk-flowers tubular, 5-toothed, 

 sterile. Scales of the involucre in 2 rows ; the exterior oblong, leafy ; the inte- 

 rior roundish, clasping the oval compressed 4-angled fertile achenia. Receptacle 

 flat, chaft'y. Pappus a slightly lobed cup-shaped crown, divided on the inside to 

 tlie base. — A low hairy stoloniferous perennial herb, with oval or spatulate- 

 oljlong opposite crenate leaves, and single heads of yellow flowers borne on a 

 long peduncle. 



1. C. Virginianum, L. — Dry open woods, Florida to North Carolina. 

 February -April. — Plant at first simple, producing from a tuft of radical leaves 

 a single peduncled head, afterward stoloniferous and branching. 



