COMPOSITE. (COMPOSITE FAMILY.) 179 



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

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

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

 ply dilated at base, or with stipuliform 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 Dakota 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 fe^sile among the leaves : pappus 

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



24. PARTHENICE, Gray. 



Allied to both Parthenium and fva. 



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 spicatety or racemosely or paniculately disposed or scattered 

 and commonly nodding heads. 



* Heads crowded in narrow spike-like clusters which are aggregated in a naked 



panicle : leaves lomj-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 involucral 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 aud 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 serrate, the base abruptly 

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

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

 heads, hispid-ciliate, as are the 3 or 4 herbaceous and unequal distinct or partly 

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



