272 Nelson : New Plants from Wyoming 



It occurs probably throughout the middle Rockies, occupying 

 dry, open slopes at moderate elevations (1800— 2500 m.). Numer- 

 ous collections of it are at hand ; the following are cited as repre- 

 sentative : 128, 1305, 3139, 5569 and 5656, the first three from 

 southern Wyoming and the last two from Yellowstone Park. 



■ 



Senecio dispar 



Rootstock almost wanting, merely a crown for the numerous 

 fibrous or semi-fleshy roots : the single stem erect, only moderately 

 stout, 5—8 dm. high, striate, appearing almost smooth and some- 

 times somewhat shining but sparsely pubescent with flat, crisped 

 hairs : leaves very variable, thin, entire or obscurely repand-dentic- 

 ulate, the mid-nerve prominent, delicately reticulate-veined ; the 

 root leaves narrow, the blade proper oblong-lanceolate and borne 

 on a margined petiole equaling or exceeding it ; the lower stem 

 leaves oblong-spatulate, tapering gradually into a broad petiole 

 which is shorter than the blade, 8—10 cm. long (including the 

 petiole), somewhat exceeding the root leaves ; the middle stem 

 leaves sessile by a broadish base, tapering gradually to the acute 

 apex ; the uppermost similar or often long-acuminate, gradually 

 smaller and becoming bract-like, giving the upper part of the stem 

 a scape-like appearance : heads few to many (5-20), campanulate, 

 10-14 mm. high, somewhat umbellately clustered or when more 

 numerous with some additional peduncles from the axils of the 

 uppermost bracts : the peduncles very unequal, the earliest short 

 and stout, some of the later ones often 7-12 cm. long and bearing 



2—4 heads : involucral bracts linear-lanceolate, minutely black- 

 tipped, y-8 mm. long: rays conspicuous, 6-10, 12-15 mm - long* 

 about 3 mm. broad : akenes flattened, obscurely striate, linear- 

 oblong, smooth or very minutely and sparsely scabro-puberulent, 

 about 4 mm. long, mostly exceeded by the soft white pappus. 



Most nearly allied to S. integerrimns Nutt. which is to be distin- 

 guished from this by its glabrous condition, its rather fleshy leaves, 

 and the less evidently margined petioles. In that the inflorescence 

 is also rather simply cymose- umbellate while in 5. dispar some 

 accessory peduncles arise in the uppermost axils. 



Occurs in the open woods among the undershrub, along the 

 streams. Laramie Hills, June 16, 1897, no. 3162; Green Top, 

 June 29, 1897, no. 3232 (type); Yellowstone Park, July 10, 1899, 



no. 5754. 



