Special Qualities of Trees and Shrubs
COLOURED AND VARIEGATED PLANTS
Some of the glories of our gardens are provided not by the brilliant colours of thebut by the more muted hues of trees and shrubs, for not only are the leaves in several tints and hues of green, but they also come in white, cream, yellow, gold, orange, red, purple, silver, grey and glaucous blue-green. Some of these colours are encompassed in the normal life cycle of the tree or shrub, beginning in the spring with the soft green breaking of the opening buds, the colour gradually losing its yellow and turning a darker green until autumn when the chlorophyll disappears and the leaves turn brown and fall or perhaps become a more spectacular orange and yellow and scarlet before they go.
Many varieties of trees and shrubs maintain a striking leaf colour during the season, and some evergreens hold their colour throughout their lives. These permanent plants with variegated foliage are of the greater value for they enable us to create permanent blocks of colour of particular importance in the winter, when among the dark and dismal leaflessness suddenly shines through the cheerful gold of Chamaecyparis lawsoniana ‘Lanei Aurea’ or one of the other invaluable golden evergreens.
It is impossible to draw a firm and definite line between the various coloured foliages but in their rough categories here are a few of the best of these fine plants. Among those trees with variegated white, cream or pale yellow leaves perhaps the most spectacular and beautiful is the poplar, Populus candicans ‘Aurora’, which produces white, cream, green and pink leaves in the late spring. These fantastic colours do not last, but they are wonderful when they are there. Look also for some of the variegated maples and the lovely gold-edged leaves of the tulip tree, Liriodendron tulipifera ‘Aureo marginatum’.
There are too many cream and gold variegated shrubs to mention, many of them evergreen, from Abelia chinensis ‘Frances Mason’ through to the variegated forms of the spiky, but look particularly for some of the hollies and phormiums, the and the elaeagnus. There are even several silver and golden variegated climbers.
Some of the most useful trees and shrubs are in the gold spectrum. Among trees the golden beech and the golden poplar are recommended and the beautiful Robinia pseudoacacia ‘Frisia’ has leaves which are wonderfully coloured and attractively shaped. Among shrubs seek out Catalpa biguonioides ‘Aurea’, Acer japonicum ‘Aureum’ and the golden privet, elder and.
HABIT AND RATE OF GROWTH
Horticultural nomenclature is generally fairly intelligible once explained, but some words have a slightly different meaning from that in general use. The ‘habit’ of a plant, for example, means the overall appearance in relation to its manner of growth. So a tree is said to be erect or weeping, bushy or prostrate. This, then, is its natural habit of growth. ‘Growth’ is dependent to some extent on the habit. An erect tree, for example, will tend to grow upwards rather than outwards. So growth can be defined as the increase in size by cell division and expansion, made permanent by the thickening of cell walls and the formation of supporting and strengthening tissues such as fibre and wood — all of which may sound technical but is necessary to help explain some of the elementary essentials of modern gardening.
It is important to take note of these recorded characteristics. We read, for example, that a conifer is of prostrate habit and moderate growth. This could indicate that it will be suitable to cover and conceal an unattractiveinspection cover. Or it could prevent the frequently committed sin of planting a tender and beautiful young weeping willow in the vacant space in front of a living room window. Although the young tree will present an enchanting picture for the first two or three years, it will increasingly fill all the available space and darken the room and will eventually be taken down, only to leave a large and disfiguring stump to be concealed.
This same tree planted further down the garden could serve first to disguise and then conceal the factory chimney, for example, or to create a natural playground for the children.
With some plants and under certain circumstances it is possible to alter its habit in order to make it more useful or even more attractive, but as a general rule this is both unwise and counter-productive. When an erect growing plant is used with other similar plants to make a hedge or barrier, it is possible to stem the upright habit of growth by clipping or cutting away the top. This stimulates side growth and is normally successful, so that instead of having a plant with erect habit, you have one with a more suitable spreading nature.
All good lists and catalogues of plants give an indication of their habit and growth. Growth, for example, is usually quoted as an average height and spread for a mature tree or shrub. Maturity is usually reached in about 10 to 15 years. It is therefore a comparatively simple matter to decide whether or not a tree or shrub is likely to fit the space available for the foreseeable future.
SCENTED FLOWERS AND AROMATIC FOLIAGE
There is a tendency to dismiss all trees and many shrubs as a source of garden perfumes, expecting scent only from the flowers of herbaceous materials and a few shrubs such as, lavender and witch hazel. Yet many plants are perfumed.
The leaves of eucalyptus trees are of course scented, as are the leaves oiPopulus balsam if era with their perfume of balsam, but the boundaries of smell extend much further. Many leaves are used in various aspects of scents, unguents. Salves and in cookery. Leaves of Laurus nobilis, the bay tree, have been used in the kitchen for years, as have those of the sage, Salvia officinalis, and of rosemary. Lavender leaves and flowers are well known particularly in pot pourri and body perfumes. Some varieties of cistus produce a sap or gum so fragrant that it is used in the manufacture of perfumes.
It is the flowers that really provide the perfumes, as would be expected, although it is not generally realized just how many flowering trees are scented. The blooms of the flowering crabs and cherries are rich in scent. One of the mountain ashes, Sorbus esserteauana, gives strongly scented flowers in late spring, while the manna or flowering ash, Fraxinus ornus, produces perfumed white blooms just before this. Several of the tilias or limes are so strongly perfumed that the air is scented all around them and attracts the bees in the neighbourhood to their creamy yellow flowers in June or July.
Shrubs provide us with the widest possible list of perfumed flowers and how grateful we are for some of the earliest to scent the air in spring. In the darkest days of winter, scent is provided by the flowers of Viburnum farreri (also known as V. fragrans), of wintersweet, Chimonanthus praecox, and the witch hazel,and H. pallida. For the remainder of the year there is a constant How of perfume from flowering shrubs such as the mahonias, elaeagnus, lavenders, syringas, buddleias, daphnes and many more. How surprising, for example, to discover the powerful scent of vanilla emanating from the miniature yellow flowers oiAzara microphylla and to identify the well-known Spanish broom, Spartium junceum, as the source of a honey smell.
Among the climbers to provide familiar scents are jasmine and honeysuckle, myrtle and mimosa.
Most gardeners could make better use of their garden perfumes. Instead of spreading them about and so lessening their impact, they could concentrate them where they would be enjoyed to greatest advantage. Plant honeysuckle and species roses to waft their scents into the open bedroom windows in summer.
ORNAMENTAL FRUITS, BARK AND WOOD
We tend to favour various trees and shrubs because of their striking foliage or their beautiful flowers, thinking too seldom of the other advantages they may possess. Fruits and berries, both of which are merely seed capsules, can be beautiful too, as can bark colour. How fascinating are the peeling and curling barks of Betula papyrifera and Acergiiseum, and the brilliant red of‘Sibirica’. No garden is complete without some examples of the variety of nature as expressed not merely in flowers and foliage but in other ways.
If you are fortunate enough to have the space to grow one, look at the flowers of a horse chestnut tree, like a pyramid of tiny orchids, each flower exquisitely formed and coloured. These will be followed by large, rounded, prickly fruits containing the glossy conkers so beloved of small children. There are luscious round or conical fruits on crab trees, golden or scarlet, cherry-like or almost as large as eating apples. There are long, twisted pods on a honey locust, Gleditschia triacanthos. And the extraordinary bladder-like fruits of Koelreuteria paniculala. Medlars from the mespilus and mulberries from the Moms nigra can be collected and enjoyed. If birds allow you, you can have colourful berries — white. Yellow, pink, orange or red — on sorbus trees.
Perhaps not quite so dramatic, the range of fruits presented by the shrubs in our gardens can be even wider than those found on trees. Every colour is represented, ranging from amelanchier, with its shining red summer fruits deepening to almost black, to vitis, many of which have edible grapes.
The strawberry tree, arbutus, gives exceptional value with cinnamon-coloured bark, lily-of-the-valley flowers and the simultaneous large strawberry-like fruits. Symphoricarpus albus, the snowberry, produces white or pink berries and grows strongly. The quinces prove profitable with useful fruits following their vivid flowers. If you have bushes of both sexes, thewill produce an abundance of semi-translucent orange berries. For a change grow Corylus maxima ‘Purpurea’ and get purple hazel nuts, not the normal brown, as richly coloured as the abundant foliage.
You can expect berries on viburnums, hollies, berberis, cotoneaster,and skimmia. Less well-known shrubs which can provide a fruitful autumn include Callicarpa bodinieri, with violet berries; Dorycnium hirsutum, bearing fruit pods tinged with red; Osmanthus decora, purple-black berries; , with swollen pods like bladders; Gaultheria procumbens, bright red berries; Ruscus aculeatus, with curious leaves which bear scarlet berries in their centres; and Rhamnus frangula, with fruits beginning as red and changing gradually to a deep black.