A tree up to 100 ft high in the wild, but never even half that size in this country; trunk slender, paler than in P. tremula when young; young shoots reddish brown, glabrous. Leaves 1 to 21⁄2 in. long and wide, very broadly ovate or roundish, with a short, abrupt apex, and a broad, rounded or nearly straight base, very finely toothed, and furnished with fine hairs on the margin, dark glossy green above, pale and dull beneath, glabrous on both sides; stalk slender, two-edged, 1 to 21⁄2 in. long. Catkins 2 to 21⁄2 in. long, more slender than in P. tremula.
P. tremuloides is perhaps the most widely distributed tree of N. America, occurring throughout Canada south of the tundra and in most parts of the USA with the exception of the south-east and some of the prairie states. In the west it ranges from N.W. Mexico to Alaska. It is often confused in gardens with the Old World P. tremula, from which it differs in characters pointed out under that species. According to Aiton, it was introduced in 1812, but there is some doubt as to this; a poplar grown under the name of P. graeca, but identical with P. tremuloides, is said to have been cultivated in 1779. P. tremuloides has never succeeded very well in this country, where it is mainly represented by the following garden variety:
cv. ‘Pendula’. Parasol de St Julien. – A pendulous variety. According to a note by M. Ferdinand Cayeux in the Garden for 21st January 1886, p. 65, it was found by a foreman in the employ of Messrs Baltet at St Julien, near Troyes, in 1865. It has more slender twigs than the weeping variety of P. tremula, but it is a female, and the catkins are not so striking as the male ones of the weeping aspen.
var. vancouveriana (Trel.) Sarg. P. vancouveriana Trel. ex Tidestr. – This variety, a native of British Columbia (including Vancouver Island) and also reported from Washington and Oregon, differs from the typical state in the young shoots being downy and in the leaves being woolly when young. Trelease, who describes it as a tree 15 to 35 ft high, says it is easily distinguished from P. tremuloides by the peculiar toothing of the leaves. ‘The teeth are much larger than in any of its immediate allies and besides being crenulate are depressed so that each tooth viewed from the edge forms a double curve.’