AMENTIFERZ. 197 
Var. a is a tree usually of moderate size, though sometimes attaining 
a great height, with smooth grey bark; suckers numerous; the leaves 
2 to 6 inches long, exceeding the petiole, with much stiffer hairs on 
the underside than in P. canescens. Mature leaves on long much com- 
pressed petioles ; lamina 1 to 2 inches long by 1 to 3 inches broad, much 
resembling that of P. canescens, but more regularly and less deeply 
sinuate-serrate, the teeth curving inwards and rounded off at the apex. 
The young leaves have a few hairs above, but are quite silky and 
white beneath; they at length become quite glabrous on both sides. 
Female catkins longer and with more deeply laciniate scales than in 
P. canescens. Segments of the stigma shorter and thicker, generally 
4, rarely 6 or 8. Fruit considerably smaller and narrower. Leaf- 
buds more pointed and with scarcely any hairs except at the margins 
of the scales. 
Var. 6, at least the specimens of it I have seen, is a bush 3 to 12 
feet high, with the leaves smaller, somewhat inclining to rhombic, and 
the teeth usually curving less forward, often so little as to be rather 
dentate than serrate, though this varies much in both forms. 
Aspen. 
French, Peuplier tremble. German, Zitterpappel. 
The origin of the popular name, Aspen, is thus given by Dr. Prior: “In Chaucer 
aspe, the adjective form of which we have adopted as the name of the tree: Anglo- 
Saxon, aepse, and German aspe, words that seem to represent the sibilant sound of 
its ever-moving leaves, as in asp, Greek demic, a serpent, from its hissing ; whisper, 
wasp, and sibilo. Skinner would derive it from the Greek deruipw, palpitate, but 
the word is much older in the north than the study of Greek.” The peculiar 
trembling movement of the leaves of the aspen has given rise to much speculation, 
and various traditions. It is accounted for by mechanical facts, and the flattened 
petiole of the leaves allows the slightest motion of the atmosphere to affect the leaf, 
so that— 
* When zephyrs wake, 
The aspen’s trembling leaves must shake,” 
and, by their friction on one another, make a constant rustling sound. This trembling 
is constantly the subject of poetical allusions. In Scotland there is a superstition 
that the cross of Christ was made from the wood of this tree, and that consequently 
it never ceases to tremble, as a consequence of the terrible event in which its species 
became involved. A recent writer observes that this can hardly apply to the leaves, 
as the cross could not have been made of them; but perhaps, she adds, “they struggle 
to escape from the wicked wood on which they grow.” Gerard says, “It is the 
matter whereof women’s tongues were made (as poets and others report), which 
seldome cease wagging.” This sentiment is surely somewhat malicious. 
In its natural state, the trembling poplar forms the chief food of beavers, where 
the animal abounds; and deer, goats, and other creatures, are fonder of the spray 
and buds than those of any other tree. The wood is white and tender, and is 
employed by turners, by sculptors, and engravers. The bark is used in tanning, in 
common with that of the other species. As fuel, it is inferior, and gives but little 
heat. Its charcoal is light and soft, and is used in making gunpowder. The leaves, 
