COMPOSITE. (COMPOSITE FAMILY.) 179 



I. S. laciniatum, L. Stem 3 to 6 and even 12 feet high : radical leaves 

 a foot or two long, long-petioled, once or twice pinnately parted or below 

 divided, the divisions and lobes lanceolate to linear; canline with petiole sim- 

 ply dilated at base, or with stipuliforro and sometimes palmatifid appendages; 

 upper sessile and reduced to bracts: involucre inch or more high and broad : 

 rays numerous, inch or two long, bright yellow. — Prairies, from the Dakotas 

 to Texas and eastward to Wisconsin and Alabama. 



23. PARTHENIUM, L. 



Ours is an acaulescent cespitose perennial, with the ligule wanting. 



1. P. alpinum, Torr. & Gray. Densely tufted on a thick branching cau- 

 dex, depressed, rising only 1 or 2 inches : leaves crowded, silvery -canescent with 

 a fine appressed pubescence, and villous in the axils, spatulate-linear, barely an 

 inch long, entire : heads solitary and nearly sessile among the leaves : pappus 

 a pair of oblong-lanceolate membranaceous scales. — Mountains of Wyoming. 



24. PARTHENICE, Gray. 



Allied to both Parthenium and Iva. 



1. P. mollis, Gray. Annual, with odor of Artemisia, 4 to 6 feet high, 

 paniculately branched, minutely cinereous throughout, wholly destitute of any 

 coarser pubescence : leaves all alternate, ovate, some of the larger (10 or 12 

 inches long) subcordate, acuminate, irregularly or doubly dentate, long-peti- 

 oled : heads small, 2 lines broad, numerous in loose axillary and terminal 

 somewhat leafy panicles : flowers greenish-white. — S. Colorado to Arizona. 



25. IV A, L. 



Herbs or shrubs . with entire or serrate leaves, at least the lower ones oppo- 

 site, and small spicatelj or racemosely or paniculately disposed or scattered 

 and commonly nodding heads. 



* Heads crowded in narrate spike-like dusters which are aggregated in a naked 



panicle : leaves long-petioled. 



1. I. xanthiifolia, Nutt. Tall and coarse, 3 to 5 feet high, pubescent, at 

 least when young : leaves mainly opposite, broadly ovate, ample, coarsely or 

 incisely serrate, acuminate, 3-ribbed at base, puberulently scabrous above: 

 panicles axillary and terminal : outer involueral bracts 5, broadly ovate and 

 herbaceous ; inner of as many membranaceous dilated-obovate or truncate 

 ones, which are strongly concave at maturity and half embrace the obovate- 

 pyriform and glabrate akenes. — From New Mexico to Idaho and the Sas- 

 katchewan. 



* * Heads spicately or racemosely disposed in the axils of leaves or foliaceous 



bracts, and nodding. 



2. I. ciliata, "Willd. Rather stout.. 2 to 6 feet high, strigose and hispid : 

 leaves nearly all opposite, ovate, acuminate, sparsely sen-ate, the base abruptly 

 contracted into a hispid petiole : spikes strict, 3 to 8 inches long , their bracts 

 lanceolate and ovate-lanceolate, foliaceous, surpassing the at length deflexed 

 heads, bispid-ciliare, as are the 3 or 4 herbaceous and unequal distinct or partly 

 united bracts of the involucre — From New Mexico to Nebraska and eastward. 



