160 RypDBERG: Rocky MOUNTAIN FLORA 
tapering below into petioles about 3 cm. long ; inflorescence corym- 
biform; heads about 4, about 12 mm. high; involucres obconic- 
turbinate, floccose at the base ; bracts linear, gradually acute ; rays 
pale-yellow, 8-9 mm. long, 3 mm. wide. 
This species is probably most closely related to S. pentodontus, 
but distinguished by the peculiar involucre, which tapers gradually 
into the peduncles. 
Cotorabo: Lake City, 1878, 7. N. Pease. 
Senecio multicapitatus Greenman, sp. nov. 
Perennial with a thick woody root; stem 4-10 dm. high, yel- 
lowish, glabrous, branched and broom-like, leafy ; leaves irregu- 
larly pinnately dissected into linear-filiform lobes, 1—1.5 mm. wide, 
or the upper simple and linear-filiform, somewhat fleshy, glabrous 
and yellowish-green ; heads in a corymbiform inflorescence, nu- 
merous, almost cylindric, 7-8 mm. high, about 4 mm. in diam- 
eter; bracts 8-10, yellowish, linear, gradually acute, glabrous and 
shining ; calyculate ones small, subulate; rays pale-yellow, 7-8 
mm. long and 2 mm. wide; achenes striate, grayish strigose- 
hispidulous, 
This species has been included in S. Doug/asi:, which has long 
-calyculate bracts and is confined to the west coast. .S. mu/ticap- 
itatus resembles closely S. Riddellii in habit, but differs in the 
narrow heads and few bracts. In S. Riddellii the bracts are 12-15 
and the involucre campanulate. SS. mul/ticapitatus grows on plains 
and in mountain valleys of Colorado, New Mexico, and Arizona. 
Cotorapo: Huerfano Valley, near Gardner, 1900, /. KR. Vree- 
land 651; Mt. Princeton Station, 1901, Underwood & Selby 465. 
New Mexico: Gray, Lincoln Co., F. S. Earle & Ester 5, 
Earle ; high plains north of El Capitan Mountains, 7. S. Earle & 
Ester S. Earle 388. 
Arizona: Holbrook, 1896, Myrtle Zuck. 
PRENANTHELLA Rydb. gen. nov. 
Low diffusely branched annuals, with numerous small heads 
terminating the branches. Lower leaves ample, oblong or spatulate 
in outline, more or less runcinate ; the upper reduced and bract-like- 
Involucres oblong, 4—5-flowered with as many oblong bracts and 
I or 2 small calyculate ones. Achenes gradually tapering dow?- 
ward from the truncate summit, 4—5-ridged. Pappus of white 5 
capillary bristles. 
