Aster. COMPOSITE. 173 



compressed, mostly flat and with callous marginal nerves only : pappus simple, 

 or with an indistinct short outer series. Gray, Proc. Am. Acad. xvi. 97. Con- 

 sists of A. Amellus and the following, of less marked character. 



A. alpinus, L. A span or more high, with simple erect stems from a thickish caudex, bear- 

 iiig a single large head, cinereous-pubescent : leaves entire, somewhat 3-nerved, spatulate ; 

 upper small and linear : involucral bracts loosely erect, oblong-linear, herbaceous, all nearly 



equalling the disk: rays violet : akeues hirsute: usually a manifest short outer pappus. 



Spec. ii. 872; Jacq. M. Austr. t. 88; But. Wag. t. 199; Hook. Fl. ii. 6. Arctic shores, 

 PMij. Alpine region of northern Rocky Mountains, down to about lat. 49, Drumitminl, 

 Burke, Bourgeau, Macoun. The American plant mostly with fewer and shorter rays. (En 

 N. Asia.) 



2. MEGAL^STRUM. Head very large (an inch in diameter exclusive of the 

 large and numerous rays, pedunculate and solitary, terminating rigid branches) : 

 bracts of the hemispherical involucre imbricated in 2 or 3 unequal series, some- 

 what herbaceous, gradually attenuate-acuminate : akenes oblong, compressed, 

 2 4-nerved: pappus-bristles unusually coarse and rigid, rather scanty. Gray, 

 PI. Wright, ii. 75. (Related to subsection Xylorrhiza and to Townsendia.) 



A. WYightii, GRAY, 1. c. Viscous-pubescent, a foot or more high : leaves oblong-spatulate, 



setiferous-mucronate, entire, or with one or two setiferous teeth, an inch and a half long 

 including the margined petiole, thickish, obscurely veined : bracts of the involucre ovate- 

 lanceolate or the inner narrower, rather lax, viscid, slightly scarious-margined, the caudate- 

 acuminate tips surpassing the disk : rays purple, narrowly oblong, 30 to 40 (8 or 9 lines 

 long): akenes (young) loosely pubescent: pappus white, of unequal strongly denticulate 

 bristles, the larger almost aristiform. Tuirn.^ mli/i (M<</<i/<i*fnim) Wriyhtii, Gray, Bot. 

 Mex. Bound. 78. Rocks and stony hills on the Rio Grande, S. W. Texas, from the mouth 

 of the great canon, Wrlyht, Bigdow. 



A. tortifblius, GRAY. Tomentose-pubescent, at length glabrate, 2 feet high: leaves from 

 oblong to narrowly lanceolate, rigid, spinulosely dentate and acuminate, sometimes incisely 

 pinnatifid, veiny: involucral bracts narrower and more numerous, lanceolate-subulate, rigid, 

 the longest barely equalling the disk : rays pale purple or violet, often an inch long : akenes 

 sericeous-canesceut : pappus at length ferruginous, deciduous in a ring. Proc. Am. Acad. 

 vii. 353, & Bot. Calif, i. 323, not Michx. Aplopappus tort I fol! us, Torr. & Gray, Jour. Bost. 

 Soc. Nat. Hist. v. 109. Mountains bordering the Mohave Desert, S. E. California to S. 

 Utah, f'ri'Hiunf, Ncwberri], Cooper, &c. 



3. HELE^STRUM. Heads mostly smaller : pappus (simple) unusually coarse 

 and rigid, the stronger bristles somewhat clavellate at tip : bracts of the involucre 

 partly or the outer wholly foliaceous and linear-lanceolate, rigid, imbricated in 

 several series, but the outermost little shorter than the inner : receptacle alveo- 

 late or fimbrillate : style-appendages filiform-subulate : akenes narrow and mostly 

 slender, little compressed, 8-10-nerved, nearly glabrous: leaves all linear and 

 entire or with some spinulose teeth, rigid, one-nerved and with obscure lateral 

 nerves : rays numerous and elongated : pappus ferruginous or tawny. Gray, 

 Proc. Am. Acad. xvi. 97. Jfeleastrum, DC. Prodr. v. 263. 



* Leaves as if gramineous, and bearing some spinuliform serratures or denticulations, mostly cus- 

 pidate at tip, smooth and glabrous: stems simple from a tuberiform moNtnrk, strict and slender, 

 rigid, 2 feet high, pilose below, or the base of the leaves ciliate with some long and jointed hairs: 

 flowering in summer. 



A. eryngiif olius, TORE. & GRAY. Stems bearing solitary or 2 or 3 large heads : leaves 

 mostly lanceolate-linear (2 or 3 lines wide, the larger 4 inches long, upper ones gradually 

 reduced to erect bracts): involucre hemispherical, very many-flowered; its bracts linear- 

 lanceolate, attenuate into an almost setiform cusp : rays an inch long, pale blue or white. - 



