=E.= Buds not glutinous; leaves white-woolly beneath when young, 4. =E.= Buds very glutinous; leaves large, shining green on both sides, 8. [Illustration: P. álba.] 1. =Pópulus álba=, L. (WHITE POPLAR OR ABELE TREE.) Leaves roundish, slightly heart-shaped, wavy toothed or lobed, soon green above, very white-cottony beneath even when old; buds without the sticky coating common in the genus. Branches very white with down when young. Root creeping and producing numerous suckers. A large tree, 50 to 80 ft. high, of rapid growth, often cultivated; from Europe. Leaves and branches very variable, forming several named varieties in the catalogues of the nurseries. [Illustration: P. tremuloìdes.] 2. =Pópulus tremuloìdes=, Michx. (QUAKING-ASP. AMERICAN ASPEN.) Leaves roundish heart-shaped, with a short sharp point, and small, quite regular teeth; downy when young, but soon smooth on both sides; margins downy. Leafstalk long, slender, compressed, causing the leaves to tremble continually in the slightest breeze. Leaf with 2 glands at the base on the upper surface; buds varnished. A medium-sized tree, 30 to 60 ft. high; bark greenish-white outside, yellow within, quite brittle. Common both in forests and in cultivation. [Illustration: P. grandidentàta.] 3. =Pópulus grandidentàta=, Michx. (LARGE-TOOTHED ASPEN.) Leaves large, 3 to 5 in. long, roundish-ovate, with large, irregular, sinuate teeth; and when young densely covered with white, silky wool, but soon becoming smooth on both sides; leaf, when young, reddish-yellow; petiole compressed. A large tree, 60 to 80 ft. high, with rather smoothish gray bark. Woods; common northward, rare southward, except in the Alleghanies. Wood soft and extensively used for paper-making. [Illustration: P. heterophýlla.] 4. =Pópulus heterophýlla=, L. (DOWNY-LEAVED POPLAR.) Leaves heart-shaped or roundish-ovate with small, obtuse, incurved teeth; white-woolly when young, but soon becoming smooth on both sides except on the veins beneath. Leafstalk slightly compressed. Shoots round, tomentose. Buds not glutinous. A large tree, 70 to 80 ft. high, not very common; found from western New England to Illinois, and southward. [Illustration: P. dilatàta.] 5. =Pópulus dilatàta=, L. (LOMBARDY POPLAR.) Leaves deltoid, wider than long, crenulated all round, both sides smooth from the first; leafstalk compressed; buds glutinous. A tall tree, 80 to 120 ft. high; spire-like, of rapid growth, with all the branches erect; the trunk twisted and deeply furrowed. Frequently planted a century ago, but now quite rare in the eastern United States. From Europe. It is thought to be a variety of Populus nigra (No. 7). [Illustration: P. monilífera.]