from the pergola in that the pergola has solid
and permanent supports, its original purpose, in addition to the giving
of shade, being to support vines. The green alley, being made of stiffer
and more woody growths, only needs a temporary framework to which to
train the trees till they have filled the space and formed the shape.
Hornbeam was the tree most used in former ages, and for a simple green
alley nothing is better. Beech is also good. Several other of the
smaller trees of weeping growth should be more used for this and the
allied uses of training for arbours and other shelter-places in the
garden.

The common Plane is much used on the continent for green shelters; the
trees are pollarded at about eight feet high, and the vigorous young
growths trained down horizontally to a slight framework.

It would be interesting to make a green alley with two or perhaps three
kinds of plants whose leaf form was of the same structure. For instance,
a groundwork of Weeping Ash could soon be trained into shape, and
Wistaria would be best to grow all over and through it. The more stiff
and woody Ash would supply the eventual solid framework, as by the time
the Wistaria was making strong growth (for it is very slow to make a
beginning) the whole would be well in shape, and might dispense with the
framing of "carpenters' work" that is necessary for its first shaping.
It would be best to plant the Ash zigzag across the path so that the
main of the head of each tree might be trained across the path and down
to the ground on the opposite side, when it would occupy the space
between the two opposite trees.

It is important to further maintain the distinction between green alley
and pergola by using in the green alley only things of a permanent and
woody character; no Roses or Clematis, or any other plants of which
portions are apt to die or wear out. These are proper to the pergola,
whose permanent substructure makes it easier to cut away and renew those
of its coverings, whether structural or growing, that are liable to
partial decay.

A great many delightful things may be done with these green alleys and
green shelters. Much interest is already aroused in the pergola, and
when thinking of this it is well to consider these other ways of adding
to the comfort and charm of our gardens. One thing, however, should be
carefully considered. It should be remembered that where a path is made
more important by passing under trained green