CLASS XXir. ORDER XII. 397 



from right to left. Petioles reflexed, contorted, channelled. 

 Leaves heart shaped, acuminate, entire, beautifully marked with 

 long, distinct, single nerves, glabrous above, smooth or villous 

 beneath. Flowers minute, alternate, sessile, on long, filiform, 

 axillary peduncles. Calyx in the barren flowers in six ovate 

 segments, with six minute anthers. Fruit inversely heart 

 shaped, three winged. — Woods on the Concord turnpike, rare. — 

 May, June. — Perennial. 



POLYANDRIA. 



409. POPULUS. 

 PopuLus tre:muloides. Mich. American Aspen, 



Leaves roundish, abruptly acuminate, serrulate, 

 pubescent at the edge. Mich. f. 



The small, tremulous leaves of this Poplar have great affinity 

 to those of the European Aspen, whose quivering foliage has 

 long been proverbial. The tree somewhat exceeds the middle 

 size. The flowers appear in April, long before the leaves, in 

 pendulous, silken aments ; the calyx of the barren flowers of a 

 dark, chesnut color with a fringe of white hairs. Corolla white. 

 Anthers numerous, deep brown with white pollen. The leaves 

 are small, compared with other species, light, roundish, scarcely 

 hearted at base. The bark is smooth, and the wood light, fine, 

 soft, and perishable. 



PopuLus GRANDiDENTATA. MicJi. Large Aspen 01' Poplav. 



Petioles compressed; leaves roimd-oval, smooth 

 both sides, unequally sinuate, with large teeth, the 

 younger ones villous. Mich. f. 

 Syn. PopuLus trepida. Muhl. 



This tree is occasionally met with in our woods, but is much 

 less common than the preceding species. It is easily distin- 

 guished from the various cultivated poplars by the large, unequal 

 indentations on the margin of the leaves. The leaves, as Mi- 

 chaux observes, are covered when young with a white down, 

 which disappears as they grow older. In many instances they 

 are furnished with a pair of glands at base. The aments, which 



34 



