92 RELATIONS OF FOLIAGE-LEAVES TO ABSORBENT ROOTS. 
RELATIONS OF THE POSITION OF FOLIAGE-LEAVES TO THAT OF 
ABSORBENT ROOTS 
Anyone who has ever taken refuge from a sudden shower under a tree will 
remember that the canopy of foliage afforded protection for a considerable time, and 
that the ground underneath was either not wet at all, or only slightly so. No doubt 
some of the rain flows down the bark of the trunk, and in many species, as, for 
instance, the Yew and the Plane-tree, the volume of water conducted down the 
trunk is considerable; but in the case of most trees the rain-water which reaches 
the earth in this manner is not abundant, and in comparison with that which drips 
from the peripheral parts of the foliage its quantity is negligeable. This phenome- 
non is dependent upon the position of the foliage-leaves relatively to the horizon. 
In almost all our foliage-trees—in limes and birches, apple and pear trees, planes 
and maples, ashes, horse-chestnuts, poplars, and alders—these organs slope out- 
wards, and are so placed one above the other that rain falling upon a leaf on one 
of the highest branches flows along the slanting surface to the apex, collects there 
in drops, and then falls on to a lower leaf whose surface is also inclined outwards. 
Here it coalesces with the water fallen directly upon this leaf; and so it goes from 
one tier to another, lower and lower, and at the same time further and further 
from the axis, till a number of little cascades are formed all round the tree. From 
the under and outermost leaves of the entire mass of foliage the water falls in 
great drops to the ground, and after every shower of rain the dry area at the 
foot of the tree is surrounded by a circular zone of very wet earth. It is only 
necessary to dig at these places to convince one’s self that the tree’s absorptive roots 
penetrate the earth precisely to the wet zone. When a tree is young, its roots lie 
in a small circle, and the crown too is not extensive, so that the damp zone is 
proportionately restricted. But as the latter is enlarged there is a corresponding 
elongation of the roots in their search for moisture, and thus roots and foliage 
progress pari passw in peripheral increase. It seems not improbable that the 
custom amongst gardeners and foresters of trimming the foliage and roots of trees 
when the latter are transplanted is to be attributed to the phenomenon above 
described. For the rule is observed that the branches of the trunk and those of the 
root must be about equally shortened, and accordingly the suction - roots, as they 
develop, reach the zone of drip of the growing crown. 
A similar method of carrying off water is to be observed in coniferous trees. 
Take, for example, the Common Pine. The lateral branches are horizontal near 
the main trunk; the secondary branches curve upwards like bows The needles 
near the tip of each of the latter slant obliquely upwards from the axis, whilst 
the older needles, situated on the under side of the part of the branch which is 
almost horizontal and at some distance from its extremity, are directed obliquely 
downwards and outwards. Rain-drops striking the upturned needles glide down 
them to the bark of the branch in question, and thence to other needles whose 
