Stout, rough-hairy or slightly so, 2—8 feet high. Leaves lanceolate, triple-nerved, acute at each end, the lower ones sharply serrate and petioled, 3—6 inches long, ⅓—1 inch wide, the upper smaller, entire. Heads small, ⅛ of an inch or less high, very numerous on one side of the spreading or recurved branches of the usually large and dense panicle; involucral bracts linear, obtuse or acutish; rays 9—15 small. In open usually dry soil at the lower altitudes throughout the Rockies; flowering during July and August. [Illustration: _a_ Erigeron salsuginosus (Rich.) A. Gray. Large Purple Fleabane. _b_ Erigeron acris L. Blue Fleabane. _c_ Saussurea densa Hook. Saussurea. (⅗ Nat.)] [Sidenote: =Erigeron simplex= Greene. _Arctic Fleabane._] Stems 1—6 inches high, several from the same root. Leaves few, the basal spatulate or oblanceolate, 1—2 inches long; stem leaves linear and few. Heads ⅓ of an inch in diameter, solitary; involucre usually rough-hairy as well as woolly, bracts linear acute, rather close, rays ¼—⅓ of an inch long, white, very numerous. An alpine plant in dry ground at the higher elevations, among stones and on the moraines, flowering in July. [Sidenote: =Erigeron salsuginosus= (Richards) A. Gray. _Large Purple Fleabane._] Soft hairy above, 12—20 inches high. Leaves smooth, thick, bright green, spatulate or nearly ovate, acute or conspicuously bristle-tipped, the uppermost small and bract-like. Heads over 1½ inches in diameter; rays 50—70, purple or violet, ½—¾ of an inch long; disc bright yellow; involucral bracts linear, attenuate and spreading, glandular-hairy. A most striking violet or purple daisy on moist banks, slopes, and in moist, open woodlands; flowering during July. [Sidenote: =Erigeron asper= Nutt. _Rough Fleabane._] Stem simple or branched above, more or less hairy, sometimes roughly so, 6—24 inches high. Leaves smooth, hairy or fringed on the margin with hairs, entire, the basal ones spatulate, obtuse, 2—4 inches long, narrowed into a margined petiole; stem leaves oblong-lanceolate or linear-lanceolate, obtuse or acute, the upper smaller. Heads several or solitary, slender peduncled, ⅓—½ an inch broad; involucre hemispheric, its bracts linear, acute, or rough-hairy; rays 100—150, very narrow, violet-purple or nearly white, ⅓ to nearly half an inch long. In dry soil in the lower valleys and slopes of the Rockies; flowering in July. [Sidenote: =Erigeron cæspitosus= Nutt. _Tufted Fleabane._] Stems tufted, closely white-hairy from a deep root; simple or branched above, 6—12 inches high. Leaves white-hairy, entire, narrowly oblanceolate or spatulate, obtuse or acutish, 1—3 inches long; stem-leaves linear or linear-oblong, acute or obtuse, the upper gradually shorter. Heads solitary or several, short-peduncled, ⅓—½ an inch broad; involucre hemispheric its bracts lanceolate or linear-oblong acute, white-hairy; rays 40—60, ¼—⅓ of an inch long, white or pinkish.