168 SILVA OF NORTH AMERICA. SALICACES. 
rounded on the upper side, thin veins running obliquely almost to the margins, and slender terete 
petioles from an inch and a half to two inches in length, enlarged abruptly near the base and leaving 
when they fall large semiorbicular obcordate leaf-scars. The stipules of the first leaves resemble the 
bud-scales in size and shape and are caducous; higher on the branch they gradually decrease in size 
and thickness, and on the upper leaves they are oblong-lanceolate, thin, white and scarious, slightly 
ciliate on the margins, and about a third of an inch long, and often do not disappear until the 
leaves are almost fully grown. The flower-buds resemble the terminal leaf-buds in size and shape, 
and are covered by five or six deciduous scales similar to those of the leaf-buds. The aments appear 
in very early spring before the leaves, and are pedunculate, thin-stemmed, pendulous, densely flowered, 
from two and a half to four inches long and about a third of an inch thick; their scales are broadly 
obovate, light brown and scarious, and often irregularly three-lobed or parted at the apex, which is 
cut into short thread-like red-brown lobes. The stamens vary from twenty to thirty in number, with 
abbreviated filaments and large light red anthers, and are inserted on an oblique slightly concave 
short-stalked disk. The ovary is ovate, slightly two-lobed, and sessile in the deep cup-shaped disk, 
which has a thick and undulate margin, and is crowned by two nearly sessile large oblique dilated 
crenulate stigmas deciduous from the fruit. The fruiting aments become four or five inches in length 
when the capsules open at the end of May or early in June; these are ovate-oblong, acute and often 
curved at the apex, two-valved, slightly pitted, light brown, about a quarter of an inch long, thin-walled, 
surrounded at the base by the membranaceous disks of the flower, and raised on slender stalks from 
one twelfth to one eighth of an inch in length. The seeds are oblong-obovate, pointed at the apex, 
narrowed and truncate at the base, light brown, about one twelfth of an inch long, and surrounded by 
slender hairs which envelop the aments of the ripe fruits with thick masses of soft snow-white cotton, 
and becoming detached from the capsules are wafted with the seeds to great distances from the tree. 
Populus balsamifera is distributed from about latitude sixty-five north in the valley of the Mac- 
kenzie River, and from the Alaskan coast southward to northern New England and New York,’ central 
Michigan and Minnesota,’ the Black Hills of Dakota,’ northwestern Nebraska,* northern Montana, 
Idaho, and Oregon and Nevada. It inhabits the low and often inundated bottom-lands of rivers and 
swamp borders, and is common in all the regions near the northern boundary of the United States from 
Maine to the western limits of the Atlantic forest, in the maritime provinces of Canada, and in southern 
Labrador as far north as the shore of Richmond’s Gulf on Hudson’s Bay; it is abundant, although not 
large, along all the streams which flow into James’s Bay, and mto Hudson’s Bay from the southwest 
as far north as Fort Churchill ; it is common and of large size in the region north of the Great Lakes,” 
and it is the characteristic tree of the alluvial bottom-lands of the streams which flow through the 
prairie region of British America, attaining its greatest size on the islands and banks of the Pease, 
Athabasca, and other rivers which form the Mackenzie, which carries down great trunks of the Balsam 
Poplar, undermined by the shifting currents of the turbulent streams of the north, to bleach upon the 
shores of the Arctic Sea;° it is also abundant in the valley of the upper Yukon;’ and on these 
northern bottom-lands is replaced by the Spruce as the subsoil becomes cold by the dense shade made 
by the Poplars and Willows which first cover the surfaces exposed by the washing away of banks and 
the formation of islands; in the United States west of the Red River of the North it is less common 
and of smaller size. 
? Professor William R. Dudley found in 1885 on the steep woody 3 Williams, Bull. No. 43, South Dakota Agric. Coll. 104. 
banks of the ravine at Taughannock Falls, near the west side of 4 Bessey, Rep. Nebraska State Board Agric. 1894, 104. 
Cayuga Lake, in western New York, a number of old trees of this 5 Provancher, Flore Canadienne, ii. 583. — Brunet, Cat. Vég. Lig. 
species which may have grown there without the intervention of Can. 55. — Bell, Rep. Geolog. Surv. Can. 1879-80, 45°. — Macoun, 
man, although this is much farther south than Populus balsamifera Cat. Can. Pl. 456 ; Trans. Roy. Soc. Can. iv. 7. 
usually extends in New York state (Bull. Cornell University, ii. 92 8 Richardson, Franklin Jour. Appx. No. 7, 766. 
[Cayuga Fi.]). 7G. M. Dawson, Garden and Forest, i. 58. 
” Macmillan, Metasperme of the Minnesota Valley, 180. 
