AMERICAN MIDLAND NATURALIST. tiy 
characteristic of this species: they are dark green above and 
densely white tomentose beneath, cordate or truncate, obscurely 
5-parted,—three lobes prominent, and the two basal lobes small, 
unequally serrate, 8-10 cm. or longer, and somewhat broader. The 
normal leaves are smaller, ovate, cordate, cordate-angular or rotund, 
4-6 cm. long and somewhat narrower, white tomentose when 
young, canescent in age. Branchlets and buds more or less white 
tomentose. Pistillate catkins. 5-8 cm. in length; flowers crowded, 
olive colored, style very short: stigmata filiform, lobed. I have 
not observed any male trees in America. "The species is found in 
cultivation in the Mormon settlements in Utah and Idaho. "There 
are several trees about an abandoned nursery near Washington, D.C. 
: Populus alba as we understand it, is a strikingly handsome tree. 
The clear gray bark of trunk and branches, the dark green upper 
and the ‘‘snow white’’ nether face of the leaves produce an effect 
which no other poplar can do, with the exception perhaps of our 
American Quaking Aspen after a frost. 
II. POPULUS CANESCENS. 
This species has been referred to above. "That it was embraced 
in the earlier concept of P. alba there is little room for doubt as 
there are more characters in common between 2. alba and P. cane- 
scens than between the latter and P. tremula. P. canescens appears 
to occupy a mean position between 2. alba and P. tremula, and 
although its claim to specific rank has been disputed by many its 
different aspect would entitle it to be classed as a species. It is 
difficult to distinguish the normal leaves of P. canescens from those 
of P. a/ba asthey vary very much in both species both as to form 
as well as to pubescence. The leaves of the rootshoots in P. cane- 
scens vary from cordate-ovate and somewhat 5-lobed to nearly 
orbicular with variously indented margins, —crenate to irregularly 
dentate. The branchlets are sometimes canescent but usually 
glabrous and of a rich chestnut color. 
As noted above the uppermost branches and rootshoots in P. 
alba bear the large 3-lobed, tomentose leaves so characteristic of the 
species. In 2. canescens, on the other hand, the large abnormal 
leaves are found principally on the rootshoots, if my observations 
prove correct. The principal synonyms of this plant are: 
Populus alba minoribus foliis Lobel. Icon. 2:193. 1581. C. 
Bauh. Pin. 429. 1623. Weinm. Iconogr. 136. t. 826. f. 
B. 1745 
