528 COMPOSITAE (COMPOSITE FAMILY) 



slender decumbent flowering stems 10-15 cm. high; herbage subcinereous with 

 a fine appressed pubescence of straight hairs: basal leaves 7-12 cm. long in- 

 cluding the short petiole, linear-lanceolate, acute at both ends, entire, 3- 

 nerved; stems with few and rather remote, sessile, linear-lanceolate leaves: 

 heads commonly solitary, rarely 2 or 3, on slender naked peduncles; bracts 

 of the rather small involucre subequal, hispid at the very base: rays 30 or 

 more, rather narrow, purplish: achenes sparsely strigose-hispid ; bristles of 

 the pappus fine and fragile, subtended by an obscure, short-setiform outer 

 series. Common in the foothills of our mountains. 



24. Erigeron pumilus Nutt. Gen. 2: 147. 1818. Stems tufted, slender, 

 simple or branched, 1-2.5 dm. high: leaves entire, hirsute, the lower and 

 basal ones narrowly spatulate or linear, petioled, 2-10 cm. long, 2-4 mm. wide; 

 stem leaves linear: heads 12-20 mm. broad, short-peduncled ; bracts linear, 

 acute, hirsute: rays 50-80, white, 6-8 mm. long, at length deflexed: pappus 

 double, the outer row of bristles short and more or less intermixed with the 

 inner; achenes pubescent. Dry sandy plains; South Dakota to Kansas and 

 west to Utah and Idaho. 



25. Erigeron corymbosus Nutt. Trans. Am. Phil. Soc. 7: 308. 1841. Stems 

 erect from a creeping rootstock, often 3-4 dm. high, soft-cinereous or some- 

 times hispidulous with mostly spreading short pubescence: radical leaves 

 narrow-lanceolate or spatulate-lanceolate, largest 8-12 cm. long, 6-8 mm. 

 wide, 3-nerved; the cauline linear and narrow: heads sometimes solitary, usually 

 several and corymbosely disposed on short slender peduncles; involucre 

 6 mm. high, canescently pubescent: rays 30-50, mostly narrow and 6-10 mm. 

 long, blue or violet, apparently sometimes white. (E. Nelsonii Greene, 1. c. 

 294.) Colorado to Montana and far northwestward. 



26. Erigeron caespitosus Nutt. 1. c. 307. Stems tufted, canescent, simple 

 or branched above, 1.5-3 dm. high: leaves canescent or pubescent, entire, the 

 lower and basal ones petioled, narrowly oblanceolate or spatulate, 2-7 cm. 

 long: heads solitary or several, short-peduncled, 25-35 mm. broad; bracts 

 lanceolate or linear-oblong, acute, canescent: rays 40-60, 6-12 mm. long, 

 white or pinkish: pappus double, the outer series of very short bristles. (E. 

 subcanescens Rydb. Bull. Torr. Bot. Club 24: 294. 1897.) Dry flats and 

 ridges; throughout our range and west to the Pacific States. 



27. Erigeron concinnus (H. & A.) T. & G. Fl. 2: 174. 1842. Very hirsute 

 throughout with long, spreading, white hairs; stems several from the same root 

 or caudex, 1-2 dm. high, slender, leafy, branching above, the branches ter- 

 minated by single heads: leaves narrowly linear, elongated, entire, attenuate 

 at the base, the lowermost tapering into a slender petiole: heads 10-12 mm. 

 in diameter; bracts of the involucre linear, very acute, densely hirsute: rays 

 numerous, 12 mm. long, white to blue. The variety aphanactis [E. aphanac- 

 tis (Gray) Greene Fl. Fr. 389. 1907] is a rayless form which may occur in 

 the western part of our range. Infrequent; in the arid areas of the western 

 parts of our range to the Pacific States. 



28. Erigeron compositus Pursh, Fl. Am. Sept. 2: 538. 1814. Herbage 

 hirsute to glabrate and more or less viscidulous; stems very short, from a 

 somewhat woody creeping base, densely leafy: leaves fan-shaped in outline, 

 usually 2-3-ternately parted into linear or short and narrow spatulate lobes, 

 4-12 mm. long, on long, slender, hispid-ciliate petioles; the few on the erect 

 flowering stems 3-lobed, or entire and linear: involucre 6-8 mm. high, sparsely 

 hirsute: rays 40-60, not very narrow, white (purple or violet), mostly 6-8 mm. 

 long. (E. multifidus Rydb. Mem. N. Y. Bot. Gard. 1: 402. 1900.) Dry, 

 stony slopes, middle elevations; throughout our range and to the Pacific States. 



28a. Erigeron compositus discoideus *pray, Am. Journ. Sci. 33: 237. 

 1862. Rays wanting or abortive: heads commonly smaller. Same range 

 as the species and often growing with it. Two other varieties, nudus Rydb. 

 and incertus A. Nels., are merely glabrate forms of the species and the variety, 

 respectively. 



29. Erigeron trifidus Hook. Fl. Bor. Am. 2: 17. pi. 120. 1834. Very near 

 to the preceding, hirsute: leaves slightly fleshy, on long petioles, 3-cleft; the 



