2 PITTONIA, 
marked by a peculiar cut and indentation of the leaves; for the 
three lobes are as it were terminal, and the margin displays an 
evenness of subserrate dentation not seen in any of its allies. 
It is related to A. Douglasii, Hook., an inhabitant of the same 
region, though widely distributed; but that has a 5-lobed leaf, 
the lobes radiating, as it were, and their base is subcordate, 
while as to the margins of the lobes they are more coarsely 
and unevenly or doubly subserrate-toothed. 
A. TORREYI. Less arborescent than the preceding, the stems 
_ apt to be tufted and bushy, branches slender and with smooth 
red bark, the internodes 1} to 3 inches: largest leaves seldom 
3 inches long, about as broad, mostly 3-lobed, occasionally with 
2 small lobes developed, the base of the leaf seldom truncate 
usually subcordate, broader than long, the middle lobe not 
much larger than the other two, somewhat cuneate-obovate 
with 3 to 5 secondary shallow lobes and these with a few incise 
eeth: fruits usually 1 to 3, sometimes 5, diverging to form a 
broadly V-shaped sinus, or even more widely divergent. 
Shrub of the Californian Sierra at middle altitudes; easily 
distinguished from the Rocky Mountain A. glabrum by its com- 
paratively broader leaf (broader than long) and relatively longer 
lobes, the whole much less deeply incised. 
A. DIFFUSUM. A low diffusely branching subalpine shrub. 
occasionally several feet high ; sterile shoots slender and straight, 
with internodes twice exceeding the small leaves: foliage mostly 
trifoliolate, the leaflets cuneate obovate, 4 to # inch Jong, coarsely 
toothed, the slender ascending petioles often an inch long or 
more: linear-oblong sepals and petals greenish and striate- 
nerved ; stamens very short: fruits large, with broad almost 
oblong wings of nearly equal width from apex to base and 
strongly divergent. 
Known only in specimens collected by myself near the summit 
of the West Humboldt Mountains, Nevada, 29 July, 1895. The 
species is noteworthy as being a low intricately branched bush, 
with leaves almost as small ag those of a Sibbaldia and somewhat : 
