Rydberg : Rocky Mountain flora 655 



has very narrow, linear outer bracts and usually purplish or bluish 

 rays. A. Osterhoutii grows along ditches at an altitude of about 

 i 500 m. 



Colo k a do : New Windsor, 1899, Osterhout 2306 (type) ; also 

 1898, p, and 1900, 2328. 



Aster corymbiformis sp nov. 



About 3 dm. high ; stem strict, branched above, pubescent on 

 decurrent lines ; leaves linear, 5-8 mm. long, scabrous on the 

 margins, otherwise usually perfectly glabrous, half-clasping ; in- 

 florescence leafy, corymbiform ; heads about 8 mm. high ; bracts 

 linear-lanceolate, very acute, glabrous, rather firm, with an oblan- 

 ceolate green tip, in about 3 series of nearly equal length ; rays 

 white or purplish, about 7 mm. long and I mm. wide. 



This is perhaps nearest related to A. paniculatus, but in habit 

 reminding somewhat of A. adseende/is. From the former it differs 

 in the strict habit, the corymbiform inflorescence and the entire 

 leaves. From A. adsccndeiis it differs in the more numerous 

 heads and the bracts, the outer of which at least are oblanceolate 

 and obtuse in A. adsceiulens. 



Colorado: West Cliff, 1896, Shear 3460 (type); also 3813 

 and ?8ip; Parlin, Gunnison Co., 1901, B. H. Smith 114 and 

 116 (?). 



Aster Tweedyi sp. nov. 



Perennial with a horizontal rootstock ; stem simple, usually 

 purplish, pubescent only on decurrent lines, about 4 dm. high ; 

 leaves oblanceolate, acute, glabrous except the ciliate margin, 

 rather firm, often 1 dm. long ; the lower with a winged petiole ; 

 the upper sessile and half clasping ; inflorescence paniculate, leafy ; 

 heads about 1 cm. high ; bracts in about 3 series, linear or ob- 

 lanceolate, not very unequal in length, the outer mostly green and 

 obtuse, the inner with green tips and midrib, whitish on the sides 

 below ; rays rose or purple, 8-10 mm. long and 1.5 mm. wide . 



This species is related to A. adseendeus but differs in the stouter 

 habit, broader and firmer leaves and larger heads. It grows in 

 valleys at an altitude of 1500-2600 m. 



Wyoming: Copperton, 1901, Tweedy 4096 (type) ; Big Horn 

 Mountains, 1899, Tzveedy 2323 ; Laramie, 1897, Elias Nelson 132. 



Colorado: Laramie River, Larimer County, 1897, Osterhcut 

 2318. 



