1. Branch with sterile and fertile flowers. 2. Sterile flower. 3. Stamen with pollen-sacs. 4. Fertile flower. 5. Fruiting branch. 6. Branch. 7. Branch with needle-shaped leaves. SALICACEAE. WILLOW FAMILY. Trees or shrubs; leaves simple, alternate, undivided, with stipules either minute and soon falling or leafy and persistent; inflorescence from axillary buds of the preceding season, appearing with or before the leaves, in nearly erect, spreading or drooping catkins, sterile and fertile on separate trees; flowers one to each bract, without calyx or corolla; stamens one to many; style short or none; stigmas 2, entire or 2-4-lobed; fruit a 2-4-celled capsule. POPULUS. Inflorescence usually appearing before the leaves; flowers with lacerate bracts, disk cup-shaped and oblique-edged, at least in sterile flowers; stamens usually many, filaments distinct; stigmas mostly divided, elongated or spreading. SALIX. Inflorescence appearing with or before the leaves; flowers with entire bracts and one or two small glands; disks wanting; stamens few. =Populus tremuloides, Michx.= POPLAR. ASPEN. =Habitat and Range.=--In all soils and situations except in deep swamps, though more usual in dry uplands; sometimes springing up in great abundance in clearings or upon burnt lands. Newfoundland, Labrador, and Nova Scotia to the Hudson bay region and Alaska. New England,--common, reaching in the White mountain region an altitude of 3000 feet. South to New Jersey, along the mountains in Pennsylvania and Kentucky, ascending 3000 feet in the Adirondacks; west to the slopes of the Rocky mountains, along which it extends to Mexico and Lower California. =Habit.=--A graceful tree, ordinarily 35-40 feet and not uncommonly 50-60 feet high; trunk 8-15 inches in diameter, tapering, surmounted by a very open, irregular head of small, spreading branches; spray sparse, consisting of short, stout, leafy rounded shoots set at a wide angle; distinguished by the slenderness of its habit, the light color of trunk and branches, the deep red of the sterile catkins in early spring, and the almost ceaseless flutter of the delicate foliage. =Bark.=--Trunk pale green, smooth, dark-blotched below the branches, becoming ash-gray and roughish in old trees; season's shoots dark reddish-brown or green, shining; bitter.