496 CocKERELL: NortH AMERICAN SPECIES OF HyMENOXyYS 
2. Rincon Mts., Arizona, Sept. 1891, G. C. Nealley. Basal 
leaves narrowly linear and entire; caudex multicipital in one 
specimen ; hair of achenes ferruginous ; pappus-scales very short, 
white tinged with ferruginous. 
It is hardly possible to rely on the character of the pappus to 
distinguish the forms of 7. Cooperi from H. Rusbyi, but the aspect 
of the plants is extremely different. 
A modified form of the above, which I call var. argyrea, oc- 
curs in the region of the Grand Cajfion. It has some resemblance 
to H. canescens biennis, but unquestionably belongs with 7. Cooperi. 
Its characters are as follows : | 
Root larger, 10 mm. broad: stem single, rather slender, 
about 6 dm. high, branching about the middle, with long, slender 
branches having few linear leaves, terminated by heads hardly 15 
mm. broad excluding rays; rays narrow, about 13 mm. long; 
outer bracts eight, pale green, straight-sided, fairly broad ; inner 
broad and fimbriate, with short green tips: disc-corollas as in 
H. canescens biennis, very pubescent and swollen basally : hair of 
achenes, and pappus, silvery-white, pappus-scales pointed but not 
awned. The stem is reddened, strongly grooved, glabrous except 
at extreme base; basal leaves as in H. canescens biennis. This 1s 
from about the Grand Cajion of the Colorado, 7,000 feet, June 
28, 1898, Dr. D. T. MacDougal, in herb. U. S. Nat. Museum. © 
Exactly the same thing is from the Grand Canon north of Flag- 
staff, June 14, about 2,000 feet on rocks, D. 7. MacDougal 207- 
I take it that this var. argyrea is more xerophytic than subsp. 
Grayi; perhaps some of the difference is not truly racial. 
»Hymenoxys Rusbyi (Gray) 
Actinella Rusbyi Gray, Proc. Am. Acad. 19: 33. 1883. 
Picradenia Rusbyi Greene, Pittonia, Sr 271. 11806. 
Tall and bushy, with very numerous rather small heads, the 
rays inconspicuous, but the disc-florets prominent and bright 
orange; involucral bracts with prominent dorsal ridges ; basal 
leaves long and linear, about 15 cm. long, simple and grass-like ; 
pappus-scales very short, subtruncate to somewhat pointed, the 
apical margin serrulate. Rusby has written on a sheet of his col- 
lection, “I mistook it for Senecio eremophilus,” a remark which at 
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