112 THE ESSEX NATURALIST
bending of the older shoots brings about the development of
adventitious ones, hence numerous new shoots sprout from the
base of the hedge and a thick barrier is produced. It is not usual
for adventitious buds to form on roots, but they are known in
some plants, for example, in the Plums. Gardeners will find
that Plums tend to produce suckers much more readily than
Apples and Pears: in digging round the tree, roots are often
damaged and adventitious buds arise from the wounded area,
giving rise to sucker shoots; removal of these suckers obviously
results in further damage with the same result; consequently
it is not surprising that sucker removal is a profitless task, for
several often appear where one has been removed.
Apart from the pruning action of the wind which has just
been mentioned, the form of many trees may be varied con-
siderably by human agency, and this operation in essentials
involves the cutting away of unwanted growths, thus stimulating
other buds to develop into shoots or pre-existing shoots to
develop more vigorously. Osier Willows are trees which in
cultivation are kept as shrubs by the continued cutting of the
branches which arise from the stool shoots, produced in the first
place by the cutting back of the main trunk. The coppicing of
trees like Hazel, Hornbeam and Chestnut for hop poles, hurdles
and pea sticks is similar. Where osiers are grown in fields
used by cattle the trunk is allowed to grow for some feet and
then cut, so that the young pliant branches, which are desired
for basket making, grow out of browsing reach of the cattle;
this type of pruning, of course, produces the familiar pollard trees.
Similarly, the forester plants his trees close together so that the
lower branches and buds are shaded and killed off; in this
way long straight trunks suitable for timber are produced.
The process occurs naturally in virgin forest. Again, in horti-
culture, many trees are shaped to man's requirements by
artificial pruning, which is carried out, apart from shaping the
tree, to give selected shoots full room to develop, to preserve
floral shoots for the purpose of obtaining maximum growth of
flowers and fruit and, of course, to remove diseased shoots.
Such pruning must not be haphazard and much will depend on
the form of the tree and its particular habit. For pruning we may
classify our trees and shrubs into three groups. 1. Those which
produce flowers on the current season's growth like bush Roses
and Buddleia variabilis and which are pruned in spring, before
the new growth appears, thus avoiding too much top growth;
2. those which produce flowers on the previous year's growth
like Rambler Roses and Forsythia and which are pruned imme-
diately after flowering (or fruiting) to encourage the new growth
which will produce next year's crop of flowers; and 3. those