a_ (Canadian Poplar), _P.
nigra_ (Black Poplar), Lombardy Poplar, and _P. tremula_ (the Aspen).
But the Poplars must not be overdone, and by pond or lakeside are often
out of place. In such places the Cardinal and Yellow-barked Willow, Sea
Buckthorn, and similar shrubs are more appropriate.

Common Alder, with its many varieties--Cut-leaved, the Golden-leaved,
and such as _Alnus incana_ and _A. serrulata_.

_Taxodium distichum_ (Deciduous Cypress); tender green in spring and
brownish red in autumn, when the leaves change colour.

_Hippophae rhamnoides_ (the Sea Buckthorn).

[Illustration: _NATURAL TREE GROWTH BY WATER (Burnham Beeches.)_]

TREES AND SHRUBS FOR MOIST (BUT NOT SWAMPY) SOIL

_Berberis Darwinii_ (Darwin's Barberry), _B. Thunbergi_ (for its
beautiful autumn leaf-colouring), Birch, Dogwoods, _Cornus alba_ and
varieties; the variety _sibirica_ has brilliant-red stems. _Cotoneaster
buxifolia_, _C. frigida_, _C. Nummularia_, _C. Simonsii_; Ash, _Myrica
Gale_ (Sweet Gale) and _M. asplenifolia_; _Ledum palustre_, _Nyssa
sylvatica_ (Tupelo tree), Mountain Ash, _Quercus aquatica_ (Water Oak),
_Q. palustris_ (Swamp Oak); _Rhamnus Frangula_ (Buckthorn). Roses
with brightly-coloured hips--_Rubus biflorus_ (White-stemmed Bramble),
_R. fruticosus fl. pl._ (Double Pink Bramble). _R. laciniatus_
(Cut-leaved Bramble), _R. spectabilis_ (Salmon Berry). _Sambucus
racemosa_ (Red-berried Elder), _Spiraea Douglasii_, _S. hypericifolia_,
_S. lindleyana_; Tamarisk. _Viburnum Opulus_ (Guelder Rose); when this
native shrub is weighed down with the rich red berry-clusters, it is a
remarkable colour picture, and the autumn leaf tints add to its beauty.

Of Conifers, mention may be made of _Tsuga canadensis_, _Picea
sitchensis_, _Cupressus thyoides_, and _Thuya gigantea_.

Bamboos: Select those of robust growth, such as _Arundinaria japonica_
(_Bambusa Metake_), _A. Simoni_, _A. Veitchii_, and _A. palmata_;
_Phyllostachys viridi-glaucescens_ and _P. mitis_.

[Illustration: _WILLOWS BY WATERSIDE._]

CHAPTER XIX

TREES AND SHRUBS FOR THE ROCK GARDEN

If we think of the changes in gardening terms which have occurred during
the last quarter of a century, there is surely significance in the
gradual transition from the Rock Garden or Alpine Garden into the more
imposing Rock Garden of our present-day language. It points to the
bolder grouping--now happily adopted in most good gardens and more in
accordance with Nature'