1 
RYDBERG: Rocky MOUNTAIN FLORA 467 
North Dakota, Montana, and northward far down the Mackenzie. 
Dr. Greenman thought that the Colorado plant should be referred 
to S. MacDougalu Heer, and so I adopted that view in the Flora 
of Colorado. I have seen two specimens from Colorado which 
may be included in S. MacDougalii, but the rest belong to what I 
think should be recognized as a distinct species. 
Senecio ambrosioides sp. nov. 
Senecio eremophilus Porter & Coulter, Syn. Fl. Colo. 82, mainly. 
1874. Not S. eremophilus Richards. 
Senecio MacDougalii Rydb. Fl. Colo. 397. 1906. Not S. Mac- 
Dougalii Heller. 1899. 
Perennial, with a stout rootstock; stem glabrous, leafy, 4-10 
dm. high; leaves lanceolate or oblanceolate in outline, pinnatifid to 
near the midrib or the lower incised, glabrous, all except the 
uppermost short-petioled, the lobes lanceolate, coarsely sige s or 
incised; heads numerous, corymbose- paniculate, 9-10 m. high, 
erect; involugres glabrous, 6 mm. high and shack as. ti soe 
bracts carinate, linear, acute, with black tips, the calyculate ones 
subulate, 4-5 mm. long; ligules light yellow, 5-6 mm. long, 1.5-2 
mm. wide; achenes minutely scabrous-puberulent on the angles. 
This species differs from Senecio MacDougalii in the larger 
heads (in S. MacDougalii only about 7 mm. high), more campanu- 
late involucres, lanceolate instead of linear divisions of the leaves, 
and the achenes scabrous-puberulent on the angles. From 5S. 
eremophilus it differs in the smaller and erect heads (in S. ere- 
mophilus 10-12 mm. high), shorter rays, and smaller leaves. 5S. 
ambrosioides grows in damp places at an altitude of 1800-3000 m. 
CoLtorApo: Green Mountain Falls, El Paso County, Aug. 2, 
1892, C. S. Sheldon (type, in herb. N. Y. Bot. Gard.); above 
Beaver Creek, July 8, 1896, Crandall 3030; Pagosa Peak, 1899, 
Baker 706; Parrott City, 1898, Baker, Earle & Tracy 475 475; Ute 
Pass, 1896, Clements 190; Colorado Springs, July, 1893, Saunders; 
Parlin, Aug. 16, 1901, B. H. Smith 127; Ruston Park, Igor, 
Clements ents 152; Mesa Yempa, 1898, Shear 3943; Chambers Lake, 
1896, Baker; Ute Pass, 1896, Shear 3695; mountains between 
Sunshine and Ward, 1902, Tweedy 4863; Empire, 1903, Tweedy 
5783; Silver Plume, 1895, Shear 4999; La Veta, 1896, Clements 
166; Silver Plume, 1894, E. A. Bessey; Georgetown, 1878, 
M. E. Jones 728; Gunnison, 1901, Baker 590. 
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