COMPOSITAE (COMPOSITE FAMILY) 531 



Aster-like; rays broad, comparatively few; disk-flowers numerous. Style- 

 appendages short, triangular-cuspidate. Achenes short, densely pubescent, 

 subterete. Erigeron in part. 



Caudex merely an enlarged crown, or the branches, if any, very short. 

 Glistening silvery-white, the pubescence microscopically fine, ap- 

 pressed 1. W. argentata. 



Greenish but more or less cinereous-lanate. 



Leaves short, mostly 1-3 cm. long 2. W. cana. 



Leaves long; mostly 4-8 cm. long . . . . . .3. W. Tweedyana. 



Caudex freely branched, forming a dense tuft, with one or more stems 



from each crown. 



Leaves 1-2 mm. wide; stems slender, curved-ascending . . .4. W. pulcherrima. 

 Leaves 2-5 mm. wide; stems stoutish, strict . . . . .5. W. cinerea. 



1. Wyomingia argentata (Gray) A. Nels. Silvery white pubescence 

 throughout very close and fine, the separate hairs indistinguishable; stems 



[-3 dm. high: radical leaves very densely clustered, linear-spatulate or broader, 

 >-5 cm. long; the cauline scattered and much smaller: heads broad, 12-15 mm. 

 ligh: rays rather broad and large, 12-14 mm. long : achenes sericeous-pubescent 

 or villous, 5-8-nerved. (Erigeron argentatus Gray, Proc. Am. Acad. 8: 649. 

 1873.) Desert regions of western Colorado to Utah and Nevada. 



2. Wyomingia cana (Gray) A. Nels. Silvery appressed pubescence ob- 

 viously strigillose under a lens, that of the involucre loose and spreading: stems 

 1-2 dm. high, leafy: the linear cauline leaves gradually diminishing upward; 

 the radical spatulate-lanceolate or narrower: head about 8 mm. high: rays 

 narrow, 6 mm. long: achenes glabrous. (Erigeron canus Gray, PI. Fendl. 67. 

 1848.) Arid areas; western Nebraska to Wyoming and New Mexico. 



3. Wyomingia Tweedyana (Canby & Rose) A. Nels. Perennial, from a mul- 

 ticipital caudex, 1-2 dm. high, simple or somewhat branched, soft-pubescent 

 below, becoming lanate above (apparently densely white, lanate when young) : 

 leaves narrowly linear, 4-8 cm. long, crowded at base, reduced and scat- 

 tered above, somewhat pubescent: heads 6-10 mm. high, a little broader, 

 terminating the simple stems or the branches: the peduncles long and naked 

 or with few bract-like leaves: involucre of numerous narrow acuminate bracts, 

 so crowded as to seem but 1-2 series, with tips a little spreading, densely 

 lanate: rays numerous, conspicuous, white: pappus double, the outer mul- 

 tisquamellate; achenes pubescent. (Erigeron Tweedyana Canby & Rose, 

 Bot. Gaz. 15: 65. 1890; E. montanensis Rydb. Bull. Torr. Bot. Club 24: 296. 

 1898.) Arid districts; Montana. 



4. Wyomingia pulcherrima (Heller) A. Nels. Bull. Torr. Bot. Club 26: 249. 

 1899. Stems about 20 cm. high, tufted at the base, simple, slender, leafy, 

 with prominent yellowish lines, pubescent with short, appressed, white hairs: 

 leaves all very narrow, about 1 mm. wide; the basal ones linear-spatulate, 

 about 1.5 cm. long; those of the stems 2-4 cm. long, linear, acute, white- 

 pubescent: peduncles a prolongation of the stems, 2-5 cm. long: heads large, 

 3.5 cm. in diameter, 7 mm. high; involucral bracts in about 4 rows, slightly 

 spreading, linear-lanceolate, with spreading pubescence: rays 20-30, either 

 white, pinkish, or violet blue, 1.5 cm. long, 2 mm. wide, emarginate. Sandy 

 hills; New Mexico and probably southern Colorado. 



5. Wyomingia cinerea A. Nels. 1. c. 250. Stems erect, fascicled, somewhat 

 striate with yellowish-green lines, about 2 dm. high, the upper part naked- 

 pedunculate, usually with a single bract: leaves linear or some of the crown 

 leaves spatulate, acute, cinereous (as are also the stems) with a short, close, 

 appressed pubescence: heads large, when fully open 3 cm. or more across; 

 involucre broadly hemispherical, about 1 cm. high; the bracts acute, cinereous 

 with a spreading, crinkled pubescence: rays 30 (more or less), 5-7-nerved, 

 white or pinkish, the tube finely pubescent as are also the disk florets, 3 mm. 

 broad, 3-toothed at the rounded apex: pappus tawny, in a single series, about 

 as long as the disk-corollas, the bristles mostly abruptly flexed one third their 

 length below the apex: achene short, striately marked with 2-4 greenish- 

 yellow lines: receptacle flat, alveolate. Desert hillsides; south central Wyo- 

 ming. 



