THISTLE FAMILY 891 



tichophyllus Greene. Alpine peaks: Mont. — Colo. — Ore. — B.C. Mont. — <Su6- 

 alp. Jl-Au. 



39. OREOSTEMMA Greene. 



Subacaulescent perennials. Leaves narrow, entire, subcoriaceous. Heads 

 solitary', terminating the scapiform stems. Involucre hemispheric; bracts sub- 

 equal, in 2-3 series, herbaceous. Rays pistillate, numerous; ligules purple. Disk- 

 flowers perfect, fertile. Style-branches with subulate or lanceolate acute ap- 

 pendages. Achenes narrow, cylindric. Pappus of brittle, barbellate deciduous 

 bristles. [Oreastrum Greene.] 



1. O. Haydeni (Porter) Greene. Low perennial, with thick woody root 

 and caudex; stem 1 dm. high or less, glabrous; basal leaves many, linear, 5-10 

 cm. long, 2-3 mm. wide, glabrous; stem-leaves shorter; head solitary; involucres 

 about 1 cm. high, 10-12 mm. broad; bracts linear, glabrous, slightly tinged with 

 purple, with narrow scarious, ciliolate margins; ligules blue, about 1 cm. long. 

 Aster pulchllus A. Gray, in part, not Willd. A. Haydeni Porter. Mountain 

 slopes: Mont. — Wyo. — Nev. Mont. — Subalp. Jl-S. 



40. ASTERIGERON Rydb. 



Low perennials, with cespitose rootstocks. Leaves alternate, the basal ones 

 numerous, the cauhne ones much reduced. Heads solitary, terminal, radiate. 

 Involucres hemispheric; bracts imbricate in 3 series, those of the inner series 

 broad, lanceolate, with reddish purple-tinged scarious margins, the rest linear. 

 Ray-flowers pistillate; hgules purplish. Disk-flowers perfect, fertile. Style- 

 branches with ovate or triangular, subulate-acuminate appendages. Achenes 

 flat, appressed pubescent. Pappus of many hispidulous bristles. In general 

 habit, involucre and fruit agreeing with Erigeron, but the stjie-tips more like 

 those of Aster. 



1. A. Watsoni (A. Gray) Rydb. Perermial, with a cespitose rootstock; 

 stems slender, decumbent, 1 dm. long or less, glabrous or nearty so; basal leaves 

 2-3 cm. long, petioled, linear-spatulate, glabrous; stem-leaves verj- small, 4-10 

 mm. long; heads solitary, peduncled; involucre about 5 mm. high and 8 mm. 

 broad; bracts oblong-lanceolate, acute, pruinose, and with some scattered hairs, 

 with purplish membranous margins; ligules about 4 mm. long, white or purplish. 

 Aster Watsoni A. Gray. Mountains: Nev. — Utah. Mont. Au. 



41. DOELLINGERIA Nees. White Aster. 



Perennial caulescent herbs, with rootstocks. Leaves alternate, ciliate, entire. 

 Heads in corjTnbiform cymes, radiate. Involucres campanulate; bracts imbri- 

 cate in 2-4 series, narrow, appressed, not herbaceous at the tips; receptacle pitted. 

 Ray-flowers few or several, pistillate; ligules white. Disk-flowers perfect; cor- 

 ollas slender, expanded into a 5-lobed limb. Anthers obtuse at the base. Ap- 

 pendages of the style-branches subulate to ovate. Achenes slightly broader 

 above. Pappus double, the outer of short bristles or squamellae, the inner of 

 capillar^' bristles, usually clavellate at the apex, tawny. 



1. D. pubens (A. Gray) Rydb. Stem 5-10 dm. high, finely puberulent; 

 leaves lanceolate or ovate-lanceolate, 5-15 cm. long, entire, acute, green and 

 scabrous above, pale and tomentulose beneath; involucres about 5 mm. high; 

 bracts linear-lanceolate, slightly tomentulose; ligules white, 4 mm. long. Aster 

 umhellatus pubens A. Gray. Meadows and open woods: Upper Mich. — Wis. — 

 Neb.— Sask. Plain. JI-S. 



42. lONACTIS Greene. 



Perennial caulescent plants, often ligneous at the base. Leaves alternate, 

 narrow, entire. Heads radiate, solitary or corjTnbose. Involucres turbinate; 

 bracts narrow, well imbricate, appressed, firm. Ray-flowers numerous; ligules 

 violet. Disk-flowers perfect; corollas with campanulate throats. Style-branches 

 with subulate appendages. Achenes pubescent, flat, with strong marginal nerves. 

 Pappus double, the inner series of capillary- bristles, the outer short, setulose. 



