COMPOSITE. (COMPOSITE FAMILY.) 161 



lower spatulate-linear, 2 to 4 inches long, 1 to 3 lines wide ; radical spatulate : 



heads broad : involucral bracts linear-subulate ; outer little shorter than inner. 



Proc. Am. Acad. xvi. 99. A. ericoides, var. strictus, Porter, Fl. Colorad. 56. 



Common in the Colorado Kocky Mountains. 



.,_ n_ s_ The numerous small heads racemosely arranged: unequal bracts well 

 imbricated, with squarrose or at least spreading herbaceous obtuse or merely mu- 

 cronate tips : cauline leaves small, linear and entire, scarcely narrowed at the 

 abrupt sessile or partly clasping base : akenes canescent-hirsute : rays white, 

 rarely tinged with blue or purple. 



12. A. multiflorus, Ait. Low, a foot or two high, bushy-branched, 

 cinereous or green : leaves rigid, scabrous-ciliate ; uppermost passing into in- 

 volucral bracts ; these mostly with obtuse tips : heads in the ordinary forms 

 little over 2 lines long, and with only 10 to 15 or 20 rays. From Arizona to 

 British Columbia and eastward across the continent. 



13. A. COmmutatllS. A foot or so high, with divergent branches : 

 heads more scattered and twice or even thrice the size of those of A. multiflorus, 

 3 or 4 lines high and broad : rays 20 to 30 : otherwise nearly as the preceding. 

 From Saskatchewan and Dakota to Utah and E. Oregon. 



H_ H_ *- +- Involucre in some imbricated and with short close tips, in others more 

 loose and herbaceous : heads when numerous either thyrsoid or open-paniculate 

 on erect or ascending branches. 

 M. Cauline leaves sessile, but neither with cordate or auriculate base (with 1 or 2 



exceptions), nor with abrupt winged petiole-like lower portion. 



= Herbage inclined to be glabrous ; the branches often pubescent in lines : leaves 

 (at least some of them) serrate or denticulate : stems branching and with sev- 

 eral to many heads: none alpine or subalpine: Eastern forms. 

 a. Involucre close and erect ; its bracts imbricated in successive lengths. 



14. A. paniculatus, Lam. Stem 2 to 8 feet high, freely and panicu- 

 lately branched : leaves from elongated oblong to narrowly lanceolate, mostly 

 attenuate-acuminate, sharply serrate or denticulate, or upper entire, thin : heads 

 about | inch high, in loose and open mostly leaf/ panicles : bracts of the invo- 

 lucre narrowly linear, with tapering acute or acuminate green tips : rays 3 or 4 

 lines long, white varying to purplish or violet. A very polymorphous species, 

 including also part of the forms heretofore included under A. Tradescanti, 

 simplex, tenuifolius, and carneus. From E. Montana to Louisiana and east- 

 ward ; abundant in the Northeastern States. 



15. A. salicifolius, (Lam ?) Ait. Resembles the preceding, equally 

 branching : leaves commonly less elongated, less serrate or entire, of firmer tex- 

 ture, apt to be scabrous, and the fine reticulation of the veinlets manifest: 

 involucre more imbricated; its bracts firmer, linear, with shorter and more defi- 

 nite green tips, these acute or obtusish: heads disposed to be thi/rsoid or racemose- 

 glomerate on the ascending branches : rays purplish to violet, rarelv white. 

 Includes A. carneus, in part. From E. Montana to Texas and northeastward ; 

 most abundant in the Mississippi Valley. 



b. Involucre loose, and less imbricated ; its bracts about equal. 



16. A. junceus, Ait. Slender, 1 to 3 feet high, the smaller plants sim- 

 ple-stemmed and with few heads, smooth and nearly glabrous : leaves linear or 



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