Rydberg : Studies on the Rocky Mountain Flora 631 



(Poir.) Britton, Trans. N. Y. Acad. 



Sci. 9 ; 182. 1890 



ipsis trifidt 



2:353. i8ir. 



Thelesperma filifoliiim A. Gray, Kew Journ. Bot I : 253. 

 1 849. 



This species grows in dry soil from Nebraska to Texas and 

 eastern Colorado. 



A 



^ 2. Thelesperma tenue sp. no v. 



slender, glabrous plant with perennial rootstock. Stems 

 1-3, slender, less than 2 mm. in diameter, light green, mostly sim- 

 ple and leafy to near the top, 1.5-4 dm. high : leaves twice pin- 

 nately dissected into linear filiform segments, mostly appressed to 

 the stem: peduncles 1-3, 5-10 cm. long : outer bracts 6-8, linear- 

 lanceolate, half as long as the inner or less ; the inner united to 

 the middle, broadly scarious-margined : rays 8-12 mm. long, 4-6 

 mm. wide : awns of the pappus very short, about half as long as 

 the width of the summit of the dark shining achenes. 



This species resembles most the preceding but has a simpler 

 stem and perennial rootstock. It grows in sandy soil at an alti- 

 tude of about 2800 m. 



Colorado : Veta Pass, 1900, Rydberg & Vre eland, S4-73 (type); 

 1870, Dr. G. W. Hulse; Plains, 1871, Wm. M. Canby. 



m 



t/ $. Thelesperma intermedium sp. nov. 



A glabrous bushy plant with a biennial or perhaps perennial 

 tap-root. Stems several, much branched and very leafy, 2-6 dm. 

 high : leaves once or twice pinnately divided into linear segments, 

 1-3 mm. wide: peduncles very numerous, 1— 1 .5 dm. long: invo- 

 lucre about 1 cm. broad : outer bracts very narrowly linear-lanceo- 

 late, about half as long as the inner; these united to about the 

 middle, scarious-margined : rays 10-12 mm. long, 6-8 mm. wide, 

 rounded, 3-toothed at the apex : teeth of the pappus longer than 

 the width of the achenes. 



This has been confused with T. ambiguum, but is of a quite 

 different habit. T. intermedium is much branched and very leafy 

 throughout, has a vertical tap-root of short duration, numerous 

 heads, rather lone outer bracts and the inner with narrow scarious 

 margins. T. ambiguum is leafy only at the base, has a creeping 

 rootstock, very short outer bracts md the inner with a very broad 

 scarious margin. 



