=4.= =Populus grandidentàta= Michaux. Large-toothed Aspen. Plate 18. A small or medium-sized tree, 1-4 dm. in diameter; bark smooth, grayish-green or whitish, becoming furrowed and dark brown on the trunks of old trees that grow in the northern part of the State, especially when growing in a swampy habitat. In the southern part of the State where the tree usually grows on the top of hills, the bark does not darken so much, frequently remaining a light to dark gray until maturity. Shoots more or less woolly at first, becoming glabrous, reddish-brown; leaves on sprouts and very young trees very velvety beneath, slightly hairy above, ovate in outline, cordate at base and with blades up to 20 cm. in length; leaves on older trees a yellow green, glabrous, ovate, blades usually 6-10 cm. long, coarsely and unevenly toothed, the base slightly rounded, rarely truncate or slightly cordate, the apex pointed or rounded; petioles strongly flattened laterally; stamens 6-12; capsule about 5 mm. long on a stalk about 1 mm. long; wood soft, light and not strong. =Distribution.=--Nova Scotia west to northern Minnesota and south to the Ohio River, and along the Alleghany Mountains to South Carolina. Found throughout Indiana, except we have no authentic records for Gibson[11] and Posey[12] Counties. In the northern part of Indiana it is found in great colonies about lakes, etc. or rarely a few trees on the crests of gravel and sand ridges. In southern Indiana it is found in the "knob" area in small colonies on the tops of the ridges associated with scrub pine and chestnut oak and is rarely found in low ground in this part of the State. =Remarks.=--This species is too rare to be of much economic importance. It could be most profitably used for excelsior and pulp wood. [Illustration: Plate 18. POPULUS GRANDIDENTATA Michaux. Large-toothed Aspen. (× 1/2.)] =5.= =Populus tremuloìdes= Michaux. Quaking Aspen. Plate 19. A straight narrow tree up to 3 dm. in diameter, usually about 1-5 dm. in diameter; bark usually smooth, greenish-white or gray, on older trees becoming rough or fissured, and turning darker; shoots glabrous or with a few hairs, turning reddish-brown the first season, later to a gray; leaves of sprouts and very small trees usually ovate with a cordate base and two or three times as large as leaves of older trees; mature leaves on older trees variable, glabrous, the prevailing type has a bluish-green leaf which is widely ovate or nearly orbicular, 3-7 cm. long, truncate or slightly rounded at the base, usually abruptly short-pointed at apex, finely and regularly serrate, the unusual type of leaf is thinner, yellow-green, ovate, 2/3 as wide as long, rounded or wedge-shaped at base, gradually tapering to a point at the apex, otherwise as the prevailing form; stamens 6-12; capsules about 6 mm. long, on stalks about 1 mm. long; wood light, soft and weak.