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Understanding a Little About How Plants Grow
The way plants become taller and broader, lengthening and extending their
branches, is by the growth that takes place from buds located at the tips of the
shoots. After that growth is completed, the new portion hardens and remains in
the same position permanently. It does not move farther up or outward. Only new
growth at the tips continues to extend
The circumference of branches and trunks increases each year,
because a new layer of growth is added on the outside. The center
part of the branch or trunk does not grow. On a tree, rose bush or
woody shrub, you can scratch away some of the outer bark and find
below it a green layer. This is the cambium, the precious part in
which growth takes place. When a tree is cut down, you can see in
its cross section the series of rings recording the amount of yearly
growth,
The location of a branch on a tree or shrub is permanent.
However, each year as the tree grows higher, the stem or trunk, and
the branches become bigger around. You must look ahead and visualize
how large those main branches may become, and provide space for them
to develop without crowding.
Growth buds are the key to pruning. They are undeveloped
branches. You will notice them on each stem or twig. In winter, on
plants that shed their leaves, these buds are easy to see. During
summer, or all year on plants with evergreen foliage, the buds will
be inconspicuous in the axils of the leaves (the spot where the leaf
stem joins the main stem). Each leaf indicates or marks the location
of a growth bud. In some plants the buds are always arranged
opposite one another along the stem--an example is lilac. In others
they are always alternate, or somewhat spirally arranges--an example
is spirea. These facts will play a part in the way you prune.
Tip or terminal buds are the most important ones. They are at the
top or end of each stem, and are larger than the lateral buds. They
are the kings, the leaders, doing the most growing, extending the
length of the branch in the direction that it is pointing. On
branches with buds arranged opposite to one another, there will be a
pair of terminal buds, and they will both be leaders and develop
equally unless something happens to one of them.
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