28 
WAYSIDE AND WOODLAND TREES. 
birch in its own qualities of colour and form, still less in that 
air and bearing which are so much more difficult to describe. 
In winter you see the full delicacy of the sprays that the lightest 
foliage hides, and in early spring this tree clothes itself, next 
after the willow, with tiny triangular leaves, inexpressibly light 
in the mass, so that from a distance they have the effect of a 
green mist rather than anything more material. When the 
tree is isolated sufficiently to come against the sky, you may 
see one of the prettiest sights in Nature — the pure deep azure 
of heaven, with the silvery white and fresh green of the birch in 
opposition. And yet it is not a crude green, for there is a good 
deal of warm red in it, which gives one of those precious ter- 
tiaries that all true colourists value.” 
Linnaeus named our common Birch Betula alba; but more 
than a century ago Ehrhart pointed out that there were two 
well-defined forms of the tree, which he proposed to separate as 
distinct species under the names of B. verrucosa and B. pube- 
scens. Hooker regards the first of these as the typical form, for 
which he properly retains the Linnaean name. It is distinguished 
by having the base of the bole covered with coarse, rough, and 
blackish bark, the smooth leaves looking as though their base 
had been cut off, and the twigs warty. The B. pubescens of 
Ehrhart appears to be a variety of Fries’ B. glutinosa, which 
Hooker treats as a sub-species of B. alba. The bark at its 
base is smooth and white, its downy leaves have a triangular 
base, and its twigs are free from warts. It sometimes assumes 
a bush-like form . 
The Dwarf Birch {Betula nand) is a distinct species, which 
occurs locally in the mountainous parts of Northumberland and 
Scotland. It is not a tree, but a bush, only two or three feet in 
height. Its firm-textured, round leaves have scalloped margins 
and short footstalks. 
The foliage of the Birch in autumn turns to a yellow hue. At 
this period — and, indeed, for a month earlier — there may be 
