206 COMPOSITE. Aster. 



Mach&ranthera setigera, Nees in Linn. xix. 722. Dry ground S. W. borders of Texas, 

 Wright, Havard. (Mex.) 



A. Canescens, PURSH. Common!}' a foot or two high and loosely much branched, even 

 from the indurated root, bearing numerous paniculate heads, sometimes dwarf and with sim- 

 ple contracted inflorescence, pale and cinereous-puberulent or minutely canescent, or greener 

 and glabrate : leaves lanceolate to linear or the lower spatulate, from entire to irregularly 

 dentate, or occasionally laciniate, the rigid teeth mostly with mucrouate-setulose tip : heads 

 when numerous 4 or 5 lines and when fewer half-inch high : involucre turbinate to hemi- 

 spherical, of rigid usually well-imbricated bracts : rays violet, 4 or 5 lines long : akenes nar- 

 row, canescent. Fl. ii. 547; Gray, Bot. Calif, i. 322. A. biennis, Nutt. Gen. ii. 155. Dle- 

 teria canescens, pulverulenta, divaricata, viscosa, & sessiliflora, Nutt. Trans. Am. Phil. Soc. vii. 

 300; Torr. & Gray, Fl. ii. 100. Ma chair anther a canescens, Gray, PI. Wright, ii. 75; Eaton, 

 Bot. King Exp. 146. The forms taken as the type of this polymorphous species are cine- 

 reous, rigid, when well developed bearing numerous heads : bracts of the involucre regularly 

 imbricated in numerous ranks, coriaceous and appressed, with the green tips short and 

 spreading, seldom at all viscous or glandular. Open and sterile ground and sandy banks of 

 streams, Saskatchewan to the eastern parts of Brit. Columbia, on the plains south to W. 

 Texas, also eastern side of the Sierra Nevada to Arizona. (Adj. Mex.) 



Var. viridis. A green form, hardly rigid, of less arid situations, either sparsely scabro- 

 puberulent or almost glabrous : involucral bracts looser, either with short and ascending or 

 longer and squarrose-spreading tips, sometimes rather hispidulous-glandular. Machceranthera 

 canescens, var. a/abra, Gray, PI. Wright, i. 89, &c. Aster Pattersoni, var. IlaUii, Gray, Proc. 

 Am. Acad. xiii. 272, is rather a subalpine form of this. W. borders of Texas to Utah. 



Var. latifolius. Green, minutely soft-pubescent, 2 feet or more high : leaves thinnish, 

 nearly membranaceous, comparatively large, sometimes spatulate-obloug and over half-inch 

 wide : heads large and few : involucre hemispherical ; tips of its bracts mostly attenuate- 

 subulate and squarrose-spreading, canescent and obscurely glandular. Dieteria asteroides, 

 Torr. in Emory Rep. 141. Mncltixranthera canescens, var. latifolia, Gray, PI. Wright, ii. 

 75. New Mexico and Arizona, in moist ground ; passes into var. tephrodes. 



Var. viscosus. Canescent or cinereous : leaves narrow, rather rigid ; the upper 

 mostly entire and the lower coarsely dentate : involucre campanulate or turbinate, squarrose ; 

 the prominent (either short or elongated) foliaceous tips of the bracts viscid-glandular, 

 either spreading or recurved. Dieteria viscosa & D. sessili flora (rays probably only abnor- 

 mally if ever at all "ochroleucous "), Nutt. 1. c. ; Torr. & Gray, 1. c. D. incana, Torr. & 

 Gray, 1. c. Diplopappus incanus, Lindl. Bot. Reg. t. 1693 (form with little viscidity to 

 involucre); Hook. Bot. Mag. t. 3882 (involucre very foliaceous-squarrose). Arid districts, 

 Wyoming to California. 



Var. tephrodes. More or less canescent, especially the hemispherical involucre of 

 the large heads ; the bracts with elongated and subulate-attenuate foliaceous tips, not gland- 

 ular; the hoary pubescence sometimes looser. A. incanus, Gray, Bot. Calif, i. 322. S. 

 California, Arizona, and New Mexico. 



-H- -H- Leaves 1-3-pinnately cleft or parted, not rigid : involucre hemispherical, its bracts mostly 

 looser: akenes more strongly striate: root commonly annual: stem diffusely branched. 

 Machceranthera, Nees, 1. c. Ditterin Pappochroma, Nutt., excl. spec. 



A. tanacetifolius, HBK. Pubescent, often rather viscid, very leafy, commonly a foot or 

 two high : lowest leaves 2-3-piunately parted ; uppermost simply pinnatifid or on the flower- 

 ing branchlets entire ; lobes short, setulose-mucronate : heads half-inch high : bracts of the 

 involucre narrowly linear, with slender mostly linear-subulate spreading foliaceous tips, or 

 the outermost almost wholly foliaceous: rays numerous (half-inch long or more), bright 

 violet : akenes rather broad, villous. Nov. Gen. & Spec. iv. 95. A. chn/santhcjnoides, Willd. 

 in Spreng. Syst. iii. 538. Machazranthera tanacetifolia, Nees, Ast. 224 ; Hook. Bot. Mag. 

 t. 4624; Gray, PI. Wright, i. 90. Chri/snpsis (Pappochroma) coronopi folia, Nutt. Jour. Acad. 

 Philad. vii. 34. Dieteria coronopifolia, Nutt. Trans. Am. Phil. Soc. vii. 300; Torr. & Gray, 

 1. c. Moist ground, Nebraska to Texas, Arizona, and borders of California. (Mex.) 



Var. pygmeeus, a low and small form, seemingly a precocious state, with less dis- 

 sected leaves, rather smaller heads, and much shorter foliaceous tips to the involucral bracts, 

 seems to connect this with the following. Machmr anther a canescens, var. humilis & var. 

 pygmcea, Gray, PI. Wright, ii. 74. New Mexico, Wright. 



