porum undulatum_, one of the most
beautiful of New Zealand evergreen trees, may be so placed, for example,
as to be exceedingly pictorial; but, as a rule, we must keep our shrubs
to an average maximum height of not more than from 4 to 5 feet, and,
generally speaking, those of still lower stature are better suited to
the ordinary Rock Garden.

[Illustration: _CISTUSES AND ROSES IN THE ROCK GARDEN._

(_In the left lower corner, Cistus hirsutus; middle, Rosa alba; to
right, R. rugosa Mme. Georges Bruant._)]

Some of the small-growing Conifers, from their compact habit and
distinct character, are especially well fitted to break the outline and
to give contrast. We think of Pines and Spruce Firs and Cedars as
majestic trees, and it is only when one comes to study them in their
manifold varieties that we find how many of these range from a height of
only a few inches to 3 feet, or at most to 4 feet.

Some species, it is true, do not lend themselves gracefully to the
dwarfing process, becoming clumpy and inelegant, but this charge cannot
be brought against many of the Cypresses and Junipers. Several of the
smaller Conifers, besides, give the advantage of distinct variations of
colour with the changing seasons. Reference is not now made to the
golden and silver forms, so-called, which occur in most of the genera,
and put on their brightest tints in spring, but to the deeper winter
colouring assumed, _e.g._ by the interesting _Retinospora ericoides_,
which alters its summer tone of dark green to purple brown on the
approach of cold weather; or by _Cryptomeria elegans_, a little less
hardy, which changes to a fine shade of bronzy crimson. Like other
plants, Conifers differ greatly as to constitution, and judgment must be
used in their choice. The dwarf alpine form of the Common Juniper
(_Juniperus communis nana_) is very hardy and slow-growing, never
becoming too rampant for the smallest Rock Garden, and shares the
blue-grey tint which is so characteristic of this beautiful species. _J.
c. alpina aurea_ is a delightful small-growing Conifer. In summer the
foliage is light yellow, and in winter heavily shaded with bronzy
yellow. Very distinct from it is the lovely prostrate Savin (_J. Sabina
procumbens_), one of the best of evergreen shrubs for the Rock Garden,
and one most restful and satisfying to the eye at all times in its deep
tones of sea green. A first-rate variety is _J. S. tamariscifolia_,
which is of very spreading g