7 8 
THE ESSEX NATURALIST. 
The salient features of B. alba are:—Height 75 to 80 feet, 
the thin branches, as they fray out, pendulous, young branches 
with resinous peltate glands, hairs absent, leaf lamina acuminate, 
doubly serrate, veins raised on upper surface, lateral lobes 
of the bracts more or less falcate (Plate VIII. fig. 2), wing of fruit 
twice or three times the diameter of the nutlets. 
The chief points respecting B. pubescens are:—Rather less 
in height than B. alba, young branches with hairs, often densely 
pubescent, not infrequently with small rudimentary verrucosities, 
leaf lamina not acuminate, irregularly serrate, veins raised on 
the under surface, more or less hairy when young, often glabrous 
or sub-glabrous later, wing of fruit as broad as or a little broader 
than the nutlets. 
The white birch has a deeply furrowed bark, but the depth 
of the furrows, and the extension from the base of the trunk 
upwards, vary considerably. 
The birch is shallow rooted. Great numbers of slender roots 
are found at very little depth below the surface of the soil and 
should there be an accumulation of decaying leaves, at or near 
the foot of the tree, numerous, thread-like rootlets, each infected 
with mycorrhiza will be found ramifying throughout the decaying 
mass. 
Birches, owing to their shallow root-system, are considerably 
damaged by heavy storms. At the present time there still 
remain evidences of the damage done to these trees by the 
great snowstorm of Sunday, 27 April 1919. It fell upon the 
birches when they were in full spring foliage. Being heavily 
weighted with snow, the shallow root-system proved quite 
inadequate to withstand the severe strain. Some trees are now 
growing out of the perpendicular, others that were brought 
to the ground were soon afterwards stripped of their branches 
(Plate VIII. fig. 1). The trunks of some still remain upon the 
ground forming an excellent nidus for saprophytic fungi. 
The groves of the High Beach—Epping plateau are, in some 
localities, as close around the church of the former place, and at 
Long Running, almost pure birch, while in others the wood is 
of the type, oak-birch-heath association, with a large propor¬ 
tion of birch. The association has not been invaded by Pinus 
sylvesiris although this tree was planted some forty years ago 
at Piercing Hill. 
