878 CARDUACEAE 



1. U. alba (Nutt.) Rydb. Stems 2-5 dm. high, smooth, scabrous, or his- 

 pidulous; lower leaves linear-oblanceolate, 3-5-ribbed, 5-15 mm. long, firm, the 

 upper linear; involucres about 5 mm. high, 5-8 mm. broad; ligules 5-6 mm. long. 

 Inula alba Nutt. Aster ptarmicoides T. & G. Rocky banks and bluffs: Vt. — 

 N.Y. — Colo. — Sask. Plain — SubmonL Jl-S. 



2. U. lutescens (Lindl.) Rydb. Stem 2-4 dm. high, scabrous, at least 

 above; leaves similar to those of the preceding species; involucres 5-6 mm. high, 

 6-8 mm. broad; ligules about 8 mm. long. Diplopappus lutescens Lindl. Aster 

 ptarmicoides lutescens A. Gray. Banks and plains: 111. — Wis. — Sask. Plain. 

 Au-S. 



37. BUCEPHALUS Nutt. 



Caulescent leafy perennials, with rootstocks. Leaves alternate, sessile, from 

 ovate to linear. Heads corymbose, radiate, middle-sized. Involucres cam- 

 panulate; bracts regularly imbricate in several series, ovate to lanceolate, not 

 foliaceous or in one species with foliaceous tips, dry and chartaceous with a dis- 

 tinct keel or midrib. Ray-flowers pistillate; ligules violet or purplish. Disk- 

 flowers numerous, perfect; corollas yellow. Style appendages subulate, acute, 

 or rarely oblong and obtuse. Achenes flat, hirsute or glabrate in age. Pappus 

 of white capillary bristles. 



Bracts all thin and acute, villous-eUiate on the margins; .style-appendages subulate. 

 Leaves ovate-oblong or broadly lanceolate; heads 10-15 mm. high. 1. E. Engelmannii. 

 Leaves lanceolate; heads 8-10 mm. high. 2. E. elegans. 



Bracts firmer, merely ciliolate, the outer obtiLse. 



Bracts with more or less foUaceous tips; involucre and branches of mflorescence de- 

 cidedly glandular, the leaves less so. 3. E. wasatchensis. 

 Bracts without foliaceous tips; plant not glandular or very rarely so. 



Inner bracts acute. 4. E. glaucus. 



All bracts obtuse or rounded and mucronate at the apex. 5. E. fonnosus. 



1. E. Engelmannii (D. C. Eat.) Greene. Stem robust, 5-15 dm. high, gla- 

 brous or slightly puberulent; leaves thin, 5-10 cm. long, loosely veined; involu- 

 cres hemispheric; bracts ovate, acute or acuminate, purple-tinged, in 5 series, 

 puberulent on the back and ciliate on the margins; ligules white, fully 1 cm. long. 

 Aster Engelmannii D. C. Eat. Mountains: Alta. — Colo. — Nev. — Wash. — B.C. 

 Submont. — Mont. Jl-S. 



2. E. elegans Nutt. Stem 3-10 dm. high, leafy, puberulent; leaves pale, 

 lanceolate, 3-5 cm. long, scabrous-puberulent ; involucres campanulate; bracts 

 ovate, acute, purple-tinged, puberulent on the back, villous-ciliate on the mar- 

 gins; ligules about 8 mm. long, white. Aster elegans T. & G. Woody mountain 

 slopes: Mont. — Wyo. — Utah — Neb. — Ore. Submont. — Mo7it. Jl-S. 



3. E. wasatchensis (M. E. Jones) Rydb. Perennial with a rootstock; stem 

 glabrous up to the inflorescence; leaves lance-oblong, acute, sessile, 4-6 cm. long, 

 rather pale, glandular-puberulent; involucres 10-12 mm. broad; bracts lanceo- 

 late, acute; rays fully 1 cm. long. A. glaucus ivasatchensis M. E. Jones. Moun- 

 tains: Utah. Mont. Au. 



4. E. glaucus Nutt. Stem branched, glabrous, 3-5 dm. high; leaves gla- 

 brous, glaucous, lanceolate, linear or oblong, acute, 3-7 cm. long, reticulatc- 

 veno.se; involucres about 6 mm. high and 8 mm. broad; bract ovate, glabrous, 

 slightly ciliolate on the margins; ligules violet or white, 8-10 mm. long. A. 

 (jlaucus T. & G. Mountains: Wyo. — Colo. — Utah. Submont. — Mont. Jl-S. 



5. E. formosus Greene. Stem glabrous, 3-5 dm. high; leaves linear, glau- 

 cous, glabrous, scabrous on the margins; involucres about 6 mm. high and 8 

 mm. broad; bracts ovate or oval, strongly purple-tinged, minutely ciliolate; 

 ligules deep blue, about 1 cm. long. Moimtains: Colo. Mont. Au. 



38. ASTER (Tourn.) L. Aster. 



Perennial herbs, usually with a rootstock, rarely with a woody caudex. 

 Leaves alternate, various. Heads corymbose, paniculate, racemose, or rarely 

 solitary, radiate. Involucres hemispheric or campanulate, or turbinate; bracts 

 imbricate in several scries, herbaceous or with herbaceous tips; receptacle flat or 



