Manual of Gardening Part 47

Very handsome; leaves silvery white beneath; among others is a weeping variety.

American elm, _Ulmus Americana._(A)(D)

One of the most graceful and variable of trees; useful for many purposes and a standard street tree.

Cork elm, _U. racemosa._(A) Softer in aspect than the last, and more picturesque in winter, having prominent ridges of bark on its branches; slow grower.

Red or slippery elm, _U. fulva._(A) Occasionally useful in a group or shelter-belt; a stiff grower.

English elm, _U. campestris,_ and Scotch or wych elm, _U. scabra_ (_U.

mantana_). Often planted, but are inferior to _U. Americana_ for street planting, although useful in collections. These have many horticultural forms.

_Non-coniferous trees for the South._

Among deciduous trees for the region of Washington and south may be mentioned: Acer, the American and European species as for the North; _Catalpa bignonioides_ and especially _C. speciosa;_ celtis; cercis, both American and j.a.panese; flowering dogwood, profusely native; white ash; ginkgo; koelreuteria; sweet gum (liquidambar); American linden; tulip tree; magnolias much as for the North; China-berry (_Melia Azedarach_); Texas umbrella-tree (var. _umbraculiformis_ of the preceding); mulberries; oxydendrum; paulownia; oriental plane-tree; native oaks of the regions; _Robinia Pseudacacia;_ weeping willow; _Sophora j.a.ponica; Sterculia platanifolia;_ American elm.

Broad-leaved evergreens of real tree size useful for the South may be found among the cherry laurels, magnolias, and oaks. Among the cherry laurels are: Portugal laurel (_Prunus Lusitanica_), English cherry laurel in several forms (_P. Laurocerasus_), and the "mock-orange" or "wild orange" (_P. Caroliniana_). In magnolia, the splendid _M.

grandiflora_ is everywhere used. In oaks, the live-oak (_Quercus Virginiana,_ known also as _Q. virens_ and _Q. sempervirens_) is the universal species. The cork oak (_Q. Suber_) is also recommended.

[Ill.u.s.tration XVI: The flower-garden of China asters with border, one of the dusty millers _(Centaurea)._]

8. CONIFEROUS EVERGREEN SHRUBS AND TREES

In this country the word "evergreen" is understood to mean coniferous trees with persistent leaves, as pines, spruces, firs, cedars, junipers, arborvitae, retinosporas, and the like. These trees have always been favorites with plant lovers, as they have very distinctive forms and other characteristics. Many of them are of the easiest culture.

It is a common notion that, since spruces and other conifers grow so symmetrically, they will not stand pruning; but this is an error. They may be pruned with as good effect as other trees, and if they tend to grow too tall, the leader may be stopped without fear. A new leader will arise, but in the meantime the upward growth of the tree will be somewhat checked, and the effect will be to make the tree dense. The tips of the branches may also be headed in with the same effect. The beauty of an evergreen lies in its natural form; therefore, it should not be sheared into unusual shapes, but a gentle tr.i.m.m.i.n.g back, as I suggested, will tend to prevent the Norway spruce and others from growing open and ragged. After the tree attains some age, 4 or 5 in. may be taken off the ends of the main branches every year or two (in spring before growth begins) with good results. This slight tr.i.m.m.i.n.g is ordinarily done with Waters's long-handled pruning shears.

There is much difference of opinion as to the proper time for the transplanting of evergreens, which means that there is more than one season in which they may be moved. It is ordinarily unsafe to transplant them in the fall in northern climates or bleak situations, since the evaporation from the foliage during the winter is likely to injure the plant. The best results are usually secured in spring or summer planting. In spring they may be moved rather late, just as new growth is beginning. Some persons also plant them in August or early September, as the roots secure a hold on the soil before winter. In the Southern states transplanting may be done at most times of the year, but late fall and early spring are usually advised.

In transplanting conifers, it is very important that the roots be not exposed to the sun. They should be moistened and covered with burlaps or other material. The holes should be ready to receive them. If the trees are large, or if it has been necessary to trim in the roots, the top should be cut when the tree is set.

Large evergreens (those 10 ft. and more high) are usually best transplanted late in winter, at a time when a large ball of earth may be moved with them. A trench is dug around the tree, it being deepened a little day by day so that the frost can work into the earth and hold it in shape. When the ball is thoroughly frozen, it is hoisted on to a stone-boat or truck (Fig. 148) and moved to its new position.

Perhaps the handsomest of all the native conifers of the northeastern United States is the ordinary hemlock, or hemlock spruce (the one so much used for lumber); but it is usually difficult to move. Transplanted trees from nurseries are usually safest. If the trees are taken from the wild, they should be selected from open and sunny places.

For neat and compact effects near porches and along walks, the dwarf retinosporas are very useful.

Most of the pines and spruces are too coa.r.s.e for planting very close to the residence. They are better at some distance removed, where they serve as a background to other planting. If they are wanted for individual specimens, they should be given plenty of room, so that the limbs will not be crowded and the tree become misshapen. Whatever else is done to the spruces and firs, the lower limbs should not be trimmed up, at least not until the tree has become so old that the lowest branches die. Some species hold their branches much longer than others.

The oriental spruce (_Picea orientalis_) is one of the best in this respect. The occasional slight heading-in, that has been mentioned, will tend to preserve the lower limbs, and it will not be marked enough to alter the form of the tree.

The number of excellent coniferous evergreens now offered in the American trade is large. They are slow of growth and require much room if good specimens are to be obtained; but if the s.p.a.ce can be had and the proper exposure secured, no trees add greater dignity and distinction to an estate. Reliable comments on the rarer conifers may be found in the catalogues of the best nurserymen.

_List of shrubby conifers._

The following list contains the most usual of the shrub-like coniferous evergreens, with (A) to mark those native to this country. The (DD) in this and the succeeding list marks those species that are found to be hardy at Ottawa, Ontario, and are recommended by the Central Experimental Farm of Canada.

Dwarf arborvitae, _Thuja occidentalis._(A)

There are many dwarf and compact varieties of arborvitae, most of which are excellent for small places. The most desirable for general purposes, and also the largest, is the so-called Siberian. Other very desirable forms are those sold as _globosa, ericoides, compacta,(DD) Hovey,(DD) Ellw.a.n.geriana,(DD) pyramidalis,(DD) Wareana_ (or _Sibirica_),(DD) and _aurea Douglasii._(DD)

j.a.panese arborvitae or retinospora, _Chamoecyparis_ of various species.

Retinosporas(DD) under names as follows: _Cupressus ericoides,_ 2 ft., with fine soft delicate green foliage that a.s.sumes a purplish tinge in winter; _C. pisifera,_ one of the best, with a pendulous habit and bright green foliage; _C. pisifera_ var. _filifera,_ with drooping branches and thread-like pendulous branches; _C. pisifera_ var.

_plumosa,_ more compact than _P. pisifera_ and feathery; var. _aurea_ of the last, "one of the most beautiful golden-leaved evergreen shrubs in cultivation."

Juniper, _Juniperus communis_(A) and garden varieties.

The juniper is a partially trailing plant, of loose habit, suitable for banks and rocky places. There are upright and very formal varieties of it, the best being those sold as var. _Hibernica (fastigiata)_,(DD) "Irish juniper," and var. _Suecica,_ "Swedish juniper." Northern juniper, _J. Sabina,_ var. _prostrata_(A) One of the best of the low, diffuse conifers; var. _tamariscifolia,_(DD) 1-2 ft.

Chinese and j.a.panese junipers in many forms, _J. Chinensis._

Dwarf Norway spruce, _Picea excelsa,_ dwarf forms. Several very dwarf sorts of the Norway spruce are in cultivation, some of which are to be recommended.

Dwarf pine, _Pinus montana,_ var. _pumilio._

Mugho pine, _Pinus montana,_ var. _Mughus._(DD) There are other desirable dwarf pines.

Wild yew, _Taxus Canadensis._(A) Common in woods; a wide-spreading plant known as "ground hemlock"; 3-4 ft.

_Arboreous conifers._

The evergreen conifers that one is likely to plant may be roughly cla.s.sed as pines; spruces and firs; cedars and junipers; arborvitae; yews.

White Pine, _Pinus Strobus._(A)(DD) The best native species for general planting; retains its bright green color in winter.

Austrian pine, _P. Austriaca._(DD) Hardy, coa.r.s.e, and rugged; suitable only for large areas; foliage very dark.

Scotch pine, _P. sylvestris._(DD) Not so coa.r.s.e as Austrian pine, with a lighter and bluer foliage.

Red pine, P. _resinosa_(A)(DD) Valuable in groups and belts; usually called "Norway pine"; rather heavy in expression.

Bull pine, P. _ponderosa._(A)(DD) A strong majestic tree, deserving to be better known in large grounds; native westward.

Cembrian pine, _Pinus Cembra._ A very fine slow-growing tree; one of the few standard pines suitable for small places.

Scrub pine, _P. divaricata_ (_P. Banksiana_).(A)

A small tree, more odd and picturesque than beautiful, but desirable in certain places.

Mugho pine, _P. montana_ var. _Mughus._(DD)

Usually more a bush than a tree (2 to 12 ft.), although it may attain a height of 20-30 ft.; mentioned under Shrubs.

Norway spruce, _Picea excelsa._(DD)

The most commonly planted spruce; loses much of its peculiar beauty when thirty to fifty years of age; several dwarf and weeping forms.

White spruce, _P. alba._(A)(DD)