COMPOSITAE (COMPOSITE FAMILY) 581 



Bot. Club 8: 98. 1881.) Dry hills; Colorado to Montana and far northwest- 

 ward. 



20a. Senecio canus Purshianus (Nutt.) A. Nels. Usually lower, more 

 densely tufted, and the leaves largely linear. (S. Purshianus Nutt. Trans. 

 Am. Phil. Soc. 7: 412. 1841.) Dry slopes and ravines; Colorado to Montana 

 and Oregon. 



21. Senecio werneriaefolius Gray, Proc. Am. Acad. 19: 54. 1883. Woolly 

 and canescent, tardily glabrate: leaves thick and coriaceous, tapering into a 

 petiole, crowded on the multicipital caudex, quite entire, erect or ascending, 

 spatulate-linear (5-8 cm. long, including the petiole-like base) to elongated- 

 oblong and short-petioled, the margins sometimes revolute: scape about 1 dm. 

 high, rather stout, bearing 2-8 heads, which are 8-10 mm. high: rays 10-12, 

 oblong, 3-4 mm. long, rarely few or wanting. Alpine; mountains of Colorado. 



22. Senecio perennans A. Nels. 1. c. Caespitose in habit or surculose- 

 spreading, forming large mats; stems simple, 1-2 dm. high: leaves crowded 

 on the crowns of the caudex and at the base of the scapose stems, of 2 

 forms; the larger narrowly elliptic to oblong, 2-4 cm. long, obtuse or acute or 

 more rarely 3-toothed, tapering into a petiole as long as the blade or longer, 

 nearly glabrous at flowering; the smaller leaves tomentose, interspersed bract- 

 like among the larger ones; bract-like leaves of the scape small, linear from a 

 broad tomentose base: heads 3-8, or rarely only 1 or 2, cymose-corymbose, 

 the terminal one overtopped by most of the others, 9-12 mm. high: rays 5-9, 

 oblong-elliptic, 5-7 mm. long: achenes glabrous. Moist places on canon 

 sides; Wyoming and Colorado, at middle elevations. 



23. Senecio petrocallis Greene, Pitt. 4: 116. 1900. Glabrous or early gla- 

 brate: leaves orbicular-obovate or oval (7-14 mm. long) to cuneate-oblong, 

 entire or 3-7-crenate-toothed at the broad summit, abruptly petioled: scapes 

 3-10 mm. high, bearing solitary or several clustered heads, which are 8-10 

 mm. high: rays 6-10, golden-yellow, 5-6 mm. long. S. petraeus. High alpine 

 throughout our range. 



24. Senecio Nelsonii Rydb. 1. c. 26: 483. 1899. Many-stemmed from a 

 densely tufted caudex whose numerous branches are reduced to short leafy 

 crowns, green and becoming glabrate, the thin tomentum in part deciduous: 

 leaves numerous, crowded on the crowns, and several on the stems, oblong, 

 lanceolate, or oblanceolate, pinnately toothed to deeply lobed or sometimes 

 divided nearly to the midrib; the segments obtuse or acute, often incisely 

 toothed; stem leaves slightly reduced upward: stems 2-4 dm. high, simple, 

 terminating in a crowded corymbose cyme, the upper pedicels sub umbellate: 

 heads 7-10 mm. high; calyculate bracts small, only 1 or 2: rays few (6-12), 

 rather large: achenes brown, glabrous, distinctly striate, 2-3 mm. long. (S. 

 rosulatus Rydb. 1. c. 27: 188. 1900.) Gravelly banks and slopes; Wyoming 

 and Colorado. 



25. Senecio Fendleri Gray, PL Fendl. 108. 1848. Very canescent with 

 floccose wool, the stem in part and the leaves on the upper surface becoming 

 glabrate in age; stem solitary or few from the crown, erect, 2-5 dm. high: 

 leaves rosulate on the crown and scattered on the stem, generally all of them 

 sinuate or pectinate-dentate, but the lower often barely sinuate : heads several, 

 in corymbose cyme: rays 6-9, usually less than 1 cm. long: achenes glabrous. 

 [S. salicinus and S. canovirens Rydb. Bull. Torr. Bot. Club 27: 186 & 187. 

 1900; S. lanatifolius Osterh. Bull. Torr. Bot. Club 32: 612. 1905 (?). The 

 last has been collected but once and the specimens look as if they might 

 be abnormal.] Southern Colorado, New Mexico, and probably Arizona. 



26. Senecio plattensis Nutt. 1. c. Perennial, more or less densely and 

 persistently tomentose or woolly-canescent; stems rather stout, solitary, or 

 sometimes tufted, 3-4 dm. high: basal leaves oval, ovate, or oblong, some or 

 all of them more or less pinnatifid, with the terminal segment much larger 

 than the lateral ones, crenulate or dentate, long-petioled : heads several or 

 numerous, compactly or loosely corymbose, conspicuously radiate. In the 

 eastern part of our range to the Missouri. 



27. Senecio uintahensis A. Nels. Perennial from a short caudex, which is 



