506 Rydberg : Studies on the Rocky Mountain Flora 



but unfortunately it is antedated by A. ciliatus Walt In A. mu/ti- 

 florns the pubescence is mostly appressed and the bracts are nar- 

 row-oblanceolate and rather thin. In A. exiguas the pubescence is 

 much denser and divaricate and the bracts are thick, broadly spatu- 

 late or obovate. In fact A. exigmts differs from the preceding only in 

 the smaller, more crowded heads and the shorter rays ; the former 

 are less than 5 mm. high and the rays are only 5-6 mm. long. The 

 New Mexican form which Gray regarded as A. hebecladits DC. and 

 for which Dr. Greene has revived the name belongs here, but is 

 evidently not A. hebecladits DC. for this is described as having 

 glabrous stem and linear bracts. 



A. exiguus grows on prairies and plains along roads, etc., and 

 westward is much more common than A. multiflorus. It ranges 

 from Vermont and Pennsylvania to Washington and south to 

 Texas and Arizona. 



Machaeranthera 



nov. 



Biennial or perhaps perennial. Stem erect or nearly so, simple 

 below, branched above, 4-6 dm. high, terete, striate, usually tinged 

 with red or purple, finely strigose-puberulent, not viscid : leaves 

 linear or linear-oblanceolate, sessile, acute, entire or sparingly 

 dentate, scabrous-ciliolate on the margins ; the largest 8 cm. long, 

 and 8 mm. wide : heads corymbose-cymose, numerous : involucre 

 10-12 mm. high, 12-15 mm. in diameter: bracts numerous, linear- 

 lanceolate with attenuate, almost terete squarrose tips, viscid- 

 puberulent: rays numerous, dark blue, about 12 mm. long and 1 

 mm. wide : pappus sordid : achenes flat, sparingly and minutely 

 strigose. 



The species grows in dry soil at an altitude of 2000-2700 m. 



Colorado : Mesas, La Veta, 1900, F. K. Vrceland, 681 (type) ; 



Telluride, 1894, F. Tweedy, 304 and joj. 



^Erigeron laetevirens sp. nov. 



■ 



Perennial with a woody tap-root. Stems several, 1.5-2 dm. 

 high, slender, erect or ascending, striate, silky strigose : basal 

 leaves very narrowly linear-oblanceolate, acute, 5-10 cm. long, 

 1-3 mm. wide, sparingly strigose; stem -leaves narrowly linear, 

 2-6 cm. long, scarcely over 1 mm. wide : heads solitary : invo- 

 lucre 12-15 mm. in diameter, grayish villous-hirsute : bracts 

 in 2-3 series, subequal, linear-lanceolate, long-acuminate : rays 

 numerous, blue or purple, 7-8 mm. long, r-1.5 mm. wide. 



