138 Rydberg : Rocky Mountain flora 



Plant glabrous or sparingly short-pubescent A. Lindleyanus. 



Basal leaf-blades lanceolate ; upper stem-leaves narrowly lanceolate 



or those of the inflorescence lance-linear. 

 Heads few ; involucres 8-9 mm. high ; rays about 15 mm. long ; 



achenes glabrous A. MacCallae. 



Heads numerous ; involucres 5-6 mm. high ; rays 8-IO mm. 



long; achenes hispidulous-strigose A. Butleri. 



Aster Wilsonii sp. nov. 

 Aster Lindleyanus /9 T. & G. Fl. N. Am. 2 : 122. 1841. 



Perennial, with a horizontal rootstock ; stem 3-6 dm. high 

 often purplish, more or less pubescent with long white, curved, 

 somewhat deciduous hairs; basal leaves petioled ; petioles 5-10 

 cm. long, densely white-ciliate, together with the midrib ; blades 

 ovate or subcordate, 5-10 cm. long, usually more or less hirsute 

 on both sides, but in age glabrate, serrate, acuminate at the apex ; 

 the lower stem-leaves similar ; the upper lanceolate, sessile, sub- 

 entire or those of the paniculate inflorescence narrowly lanceolate ; 

 involucre 7-8 mm. high, scarcely 1 cm. wide ; bracts subulate, at- 

 tenuate, with a green midrib which widens somewhat above the 

 middle; rays 8-10 mm. long, bluish purple; pappus tawny; 

 achenes glabrous. 



This species is related to Aster Lindleyanus and may grade into 

 it, but the typical specimens are very distinct, characterized by the 

 long white hairs on the petioles, midribs, and often the stem, by 

 the narrower upper leaves, the smaller heads, and the more ascend- 

 ing branches. 



British Columbia: Armstrong, 1904, £. Wilson 4.19 (type, 

 in herb. N. Y. Bot. Gard.) ; also 414, 416, and J03. 



Alberta: Grattan Creek, Aug. 16, 1 906, Macoun & Herriot 

 77073; also Edmonton, Aug. 26, 1906, 77074. 



Western Ontario: Fort Williams, Sept. 7, 1889, Dr. and 

 Mrs. N. L. Britton and Miss Millie Tiviniennan. 



Mackenzie: Fort Resolution and Mackenzie River, 1861-2, 

 R. Kennicott. 



Aster MacCallae sp. nov. 



(?) Aster praecox Lindl. in Hook. Fl. Bor.-Am. 2: 9. 1834. 

 Not A. praecox Willd. 1 8 1 3. 



Perennial, with a horizontal rootstock ; stems 3-6 dm. high, 

 often purplish, glabrous up to the inflorescence, the branches of 

 which are slightly pubescent in lines ; lower leaves with winged 



