THISTLE FAMILY 891 



tichophyllus Greene. Alpine peaks: Mont. Colo. Ore. B.C. Mont. Sub- 

 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 pulch?llus 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 cauline 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; ligules 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 style-tips more like 

 those of Aster. 



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

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

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

 mm. long; heads solitary, pedimcled; 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 corymbiform 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 

 capillary 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 

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

 Neb. Sask. Plain. Jl-S. 



42. IONACTIS Greene. 



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

 narrow, entire. Heads radiate, solitary or corymbose. 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. 



