126 FAMILIAR TREES 
This constant agitation of the foliage by the least 
breath of wind, owing to the unusual length and 
flattened form of the leaf-stalk, though commen to 
the whole genus, is most conspicuous in the case of 
the Aspen. To it the tree owes its French name, and 
it is explained scientifically by the length of the 
slender leaf-stalk and its lateral compression, so that 
the broad and heavy leaf is suspended on a sup- 
port which is itself readily acted on by the smallest 
atmospheric movement. The rustling noise, as of a 
babbling brook, is, of course, produced by the friction 
of the leaves on one another. 
In March or April the bare grey boughs or 
brownish shoots are thickly covered with catkins, and 
the male ones produce a general effect of warm vinous 
red. When the foliage appears, associations of refresh- 
ing coolness and of laughing mirth, suggested by the 
resemblance of the sound made by the leaves to the 
music of a brook, mingle, as we gaze at their pallid 
colour, and as the rising wind changes the rippling 
laugh into a long drawn sigh, with those of the deepest 
melancholy. When autumn, its “gold hand gilding 
the falling leaf,” spread its badge of splendid decay 
over each leaf in succession, the tree gains in variety 
of colour, but its rustling gives it even a more 
melancholy effect than it had before. 
The soft woods of all the Poplars are naturally 
very liable to the burrowing of insect larve. The 
caterpillars of the Goat-moth (Cos’sus ligniper’da) and 
the Wood Leopard (Zew’zera w’sculi) are among the 
most destructive. Entomologists also associate the 
Poplars with the beautiful Poplar Hawk - moth 
