200 PITTONIA. 
in northeastern California, is always a low ceespitose under- 
shrub seldom or never a foot high; and this large shrub, 
with its peculiar pubescence, should not have been referred 
to that species. Meanwhile, in its very prominently angled 
achene E. dumosum has an excellent technical character. 
-~ E.ARIDUM. Near E.umbellatum, of the same habit, though 
smaller in all its parts and rather more slender; the foliage 
less tomentose, but decidedly more equally and permanently 
so on both faces of the leaf: the peduncles more numerous 
and more slender, 5 to 10 inches high, the umbels simple, 
about 5-rayed (3 to 6) and the rays short: perianths of a dull 
cream-color (as in E. subalpinum) decidedly narrower than 
in the allied species, the segments narrowly oblong-cunet- 
form, the outer and inner ones much alike: anthers oblong; 
filaments strongly villous-ciliate about midway: achenes 
with rather narrowly lanceolate face, the angles retrorsely 
hairy at summit. 
Peculiar to the arid foothills above the Humboldt Wells 
in eastern Nevada. A near relative of E. umbellatum and 
E. subalpinum, having the mode of growth characteristic of 
the former, the pale flowers of the latter ; quite distinct from 
both in floral character, and belonging to a dry desert region 
Where neither of those species occurs or would be expected. 
E. LuTEOLUM. Near E gracile and molestum, annual, slen- 
der, usually more than a foot high, repeatedly and rather 
widely trichotomously and dic hotomously branching, with 
the small involucres solitary in the forks, and virgately 
arranged on all the ultimate branchlets: leaves mostly at 
base of the stem, small, round-ovate or orbicular, densely 
white-woolly beneath, glabrate above, less than a half-inch 
long, on petioles of more than an inch; the stem and branches 
green and glabrous: involucres many-flowered, small, pris- 
matic, a little widened upwards, glabrous or with some vil- 
losity between the short erect mucronate teeth: perianth 
light-yellow, # line long, the outer segments cuneate-obovate, 
4 
