the different countries situated in temperate climates, which are not indigenous to Britain, with the catalogues of plants considered as already introduced into this country, it will be found that there are some names of species and varieties, in the lists of almost every country, that are not in British catalogues, and, consequently, not yet introduced. There are a number of names, for example, that are not in our Hortus Britannicus. Here, then, is an important use in giving these lists, because they point out to commercial gardeners, and to amateurs and travellers who are botanists, what trees and shrubs it is desirable to enquire after in other countries; and what they should endeavour, if possible, to introduce into their own. It may also be observed, that the same names that are in the lists in preceding chapters frequently occur in British catalogues; yet it is by no means certain that in every case they are applied to the same plants. Here, then, is another point calling for the exertions of the patriotic botanist or traveller; and it may be observed respecting this point, that it will always be the safest side to err on, to reintroduce plants which are already in the country, rather than to remain in any doubt respecting our possessing them. All trees and shrubs liable to great variations, and of great utility or ornament, such as the genera Quercus, Pinus, Pyrus, Cratæ gus, &c., ought to be introduced in all their varieties. We are persuaded that there are, in France and Spain, many interesting varieties of Pìnus, and of Quércus Cérris and Q. Flex, which have not yet found their way into British gardens. The Quércus austràlis, recently introduced in consequence of the information given by Captain Cook (see p. 171.), may be cited as a proof of this; and there are, doubtless, hundreds of species and varieties of trees and shrubs in North America, that have never yet been seen in Europe. There is, therefore, ample room for exertion, to those who wish to increase the botanical riches of their country; and more especially in the case of that kind of botanical riches which adds so conspicuously and permanently to its ornament, and to its useful resources. It would, however, be a very contracted view of this subject, to limit our views to the aggrandisement of the collections of trees and shrubs in Britain. The time for believing that the exclusive possession of any benefit contributes to the prosperity or happiness of nations is gone by; and the principles of free and universal exchange and intercourse are found to constitute the surest foundation for the happiness of nations. This is so obviously true in matters of botany and gardening, that it cannot for a moment be doubted.

If it is desirable for us that we should assemble in our country the trees and shrubs of every other similar climate, it must be equally desirable that the inhabitants of every other similar climate should possess all those species for which their climate is adapted; in short, it is desirable for the advancement of civilisation and human refinement, that all the trees and shrubs of temperate climates should be distributed throughout all those climates. This will, no doubt, be the case at some future period, when the civilisation of the whole world is comparatively equalised; and, in the mean time, it may be useful to offer such hints as will contribute towards so desirable a result.

One of the first steps towards the equalisation of the plants of different regions, of similar capacities for growing such plants, is, to determine, with something like precision, what the plants of each region are. This can only be done by assembling living specimens of all of them, or of such a class of them as it may be desirable to equalise, in one garden, and cultivating them there for some time, so as to determine the species and varieties. In old countries of limited extent, such as Britain, which have been examined by botanists for two or three centuries, the establishment of botanic gardens for determining the number of indigenous species of plants may be considered unnecessary; but this is far from being the case with such countries as North America, Upper India, China, Japan, Van Diemen's Land, and a number of others. It would, doubtless, contribute to the spread, all over the world, of the trees and shrubs of North America, if one part of them could be seen in a grand national garden at New York, and another in a garden or arboretum

Q

at Charlestown; or if the whole could be assembled in one grand park and pleasure-ground at Washington. We do not, however, expect this to be done; for, in the progress of civilisation and refinement in every country, there are many much more important points to be attended to than the culture of trees and shrubs.

With a view both to introduction into any particular country, and equalisation in all similar countries, the first thing that ought to be done, after the indigenous plants of the country are clearly determined, is to assemble, in one garden in the given country, all those of all other similar countries, with a view to determining what they are. Thus, in the case of trees and shrubs, all those mentioned in the preceding lists as being foreign, with reference to the trees and shrubs of Britain, ought to be assembled and proved in one grand British national garden; and the same thing ought to be done in a similar garden in every other country. The idea may be thought chimerical; but it is hard to say what will not be done by nations, when they come to cultivate with ardour the arts of peace and of refinement. The cooperation of individuals attached to the same pursuit may, in the mean time, contribute much to the advancement of that pursuit; and hence, though in the neighbourhood of London it might be difficult, or impossible, to induce the metropolis or the government to form an arboretum of 150 acres in extent, so as to exhibit in it all the species of trees and shrubs of temperate climates, that will grow with us in the open air; yet, if the proprietors of a certain number of estates within ten miles of London were to agree each to form a collection of the species or varieties of a particular genus, and to allow these to be examined by botanists, the same result would be obtained, at least as to accuracy of nomenclature, as if the whole of the genera and species were assembled in one national garden. We have explained this cooperative system, at length, in the Gardener's Magazine, vol. xi. p. 600., and it is needless to say that it is as applicable to every other country as to England, and to every other large town as to London. The practice might, therefore, be adopted in the neighbourhood of Edinburgh and Dublin; and in that of Exeter, for the south of England; Bristol and Liverpool, for the west; York, for a central situation; Norwich, Lincoln, and Hull, for the east; and Newcastle and Carlisle, for the north.

The number of works which have been written, exclusively devoted to the description and uses of trees and shrubs, shows, in a general point of view, the estimated importance of the subject by authors; and, when we consider the rapidity of the succession of these works within a comparatively limited period, it shows the accumulation of knowledge which is continually being acquired respecting ligneous plants. In this, as in all other branches of natural history, the attention of naturalists was first directed to the objects which more immediately surrounded them in their own country; afterwards it extended to adjoining countries; and lastly, which seems to embrace the most comprehensive view of the subject, to all the other countries in the world which are similarly circumstanced in regard to climate and all that affects the growth of trees and shrubs. Hence, the first books on dendrology were merely local catalogues, enumerating the medical, or such other properties, as, in the age in which these books were produced, excited most attention; while the last are scientific descriptions, with the geography, history, and uses in civilised society, of all the species and varieties enumerated.

The conclusion which we draw with reference to the literature of trees and shrubs is, that, though there are a great many excellent works on the subject already before the public in the English, French, and German languages, yet none of these works embrace the whole subject, and bring it down to the present time; and that, consequently, we are justified in our endeavour to comprise every thing which it is desirable to know, respecting the trees and shrubs which will stand the open air in Britain, in our present Encyclopædia.

193

PART II.

OF THE SCIENCE OF THE STUDY OF TREES.

THE subject of trees, like every other subject, to be studied in the best manner, must be studied according to some methodical arrangement; and it is the purpose of this part of our work to lay down an outline of that method which we consider the best. By including in such an outline every particular which ought to be taken into consideration in the study of trees, we shall be the less likely to omit any of these particulars in giving the description and history of individual species; and the reader, also, will profit by having his attention previously directed to what this history and description ought to contain.

Trees may be studied both as individual objects, and as connected with other objects. As individual objects, they may be considered pictorially, or as component parts of the general scenery of a country; and botanically, as organised beings. As objects connected with others, trees may be studied with reference to nature, animate and inanimate, which may be considered as their natural history; and with reference to man in a state of civilisation, which may be called their economical history. We shall devote a short chapter to each of these subjects, and in a concluding one give a summary of the whole.

CHAP. I.

OF THE STUDY OF TREES PICTORIALLY, OR AS COMPONENT PARTS OF GENERAL SCENERY.

THE study of trees, as component parts of landscape, may be carried on with very little knowledge of either their natural or their economical history; and, indeed, with less knowledge of any other objects or sciences, than most studies. Experience proves that a man may excel as a graphic artist with very little knowledge beyond his art; but, at the same time, it is also found, from experience, that all the greatest artists have been, more or less, philosophers; and hence, though a knowledge of the natural and economical history of trees may not be essential for the artist who studies them pictorially, it will yet be found to render him material assistance.

The subject of this chapter naturally divides itself into the study of the forms of trees and shrubs; the study of their character and expression; and the art of delineating them pictorially.

SECT. I. Of the Study of the Forms of Trees and Shrubs.

THE first quality in a tree which will strike a general observer, coming to the study with only a few notions relative to form, will be its bulk, or the space that it occupies in the landscape which meets his eye. This bulk, or magnitude, resolves itself into height and width; and the consideration which immediately follows is, the outline that the tree makes against the sky, or against any other object which appears behind it. The next points that will probably attract notice are, the colour of the tree, and the degree of brilliancy of the lights which appear on its masses. Subsequently, the attention may be drawn to the trunk of the tree: for example, to observe whether it appears to be adequate to the support of the head; whether the head appears equally balanced on it; and whether it stands perpendicularly, or obliquely, to the sur

face on which the tree grows. The next point is, to observe whether the head is open and airy, or compact; and the last, whether the general form of the tree is regular or irregular. All these particulars are equally applicable to shrubs as to trees; with the exception of those which apply to the trunk, which is almost always wanting in what are pictorially, as well as botanically, considered as shrubs or bushes.

The different points, then, to which attention ought to be directed in the study of trees and shrubs as pictorial forms, are the following:-the height and breadth, or general magnitude, of the tree; the form and outline; the colour, light, and shade; the position of the trunk and branches; the mode of growth; the mode of tufting; the leaves, and the spray and buds.

The height and breadth of trees and shrubs vary according to their kinds, and to the soil, situation, and climate in which they grow. The trees of greatest height, in the temperate regions of the globe, are those of the pine and fir tribe; and they are those, also, which have least breadth in proportion to their height; because their branches, technically called frondose, have not the same tendency as those of other trees to increase in thickness with the age of the tree. The most bulky trees, or those which have the greatest width of head in proportion to their height, are some species of poplars, elms, oaks, &c., and the cedar of Lebanon, which, though it is a tree with frondose branches, yet, when it stands singly, has a head generally broader than its height. The highest shrubs, which grow independently of other objects of support, are, among evergreens, the common laurel, and, among deciduous kinds, the common lilac, the dogwoods, and the Guelder rose. Among the smallest trees, considered as pictorial objects, are the thorns and the spindle tree; and among the smallest shrubs are the heath, the furze, and some of the rhododendrons and azaleas.

The form and outline of trees and shrubs vary chiefly according to their kinds and their age, but partly, also, according to the physical circumstances in which they are placed; such as soil, situation, climate, and, perhaps, above all, proximity to other trees and shrubs. The natural form and outline of a tree can only be ascertained when the tree stands alone. The form which it assumes, when closely surrounded by other objects, will generally be found very different from its natural form; and, therefore, cannot be considered as characteristic of the tree or shrub. Even the climate, or the prevailing soil, or wind, will materially alter the form. The cedar, when planted in masses like the larch or the Scotch pine, produces, like them, a straight trunk, with the branches dying off from the bottom upwards; planted singly, its branches often become like so many trunks: in a sheltered situation its top will be pointed; and, in one exposed, it will become blunt or flattened, like the well-known cedars of the Chelsea Botanic Garden. Nearly the same observations may be made respecting all other trees: even the sturdy oak, in poor soils and cold elevated situations, becomes a bush; in rich soils and low situations it is a lofty tree, with a straight trunk; and in situations exposed to the sea breeze, it has the entire head of the tree leaning to one side, and presents an appearance altogether peculiar. Fig. 1. shows the effect of the sea breeze on two oaks growing on the boundary of Canford Heath, near Wimborne, in Dorsetshire; and numerous similar examples might be given from different parts of the island.

However various the outline of trees and shrubs may appear in detail, the general contour may always be reduced to some familiar or recognised form, easily retained in the memory: for example, to that of an oval, or that of an egg placed on its smallest end, which are the most common forms of trees, except in the case of those which have frondose branches; and that of an egg placed on its broadest end, or of a flattened cone, which are the most common forms of shrubs. The Lombardy poplar, the cypress, and some similar trees, may be said to have their heads in the form of an ellipsis: and others such as the common apple, thorn, &c., in that of a globe, or in that of a semiglobe. A few trees, more particularly in their young state, take the form of an inverted cone, such as the planera, as will appear by our figure of that tree at ten years' growth. Within these general forms, the greatest variety of outline

may be produced, by the receding or advancing of the terminations of the branches; by the forms of these terminations; by the manner in which they are clustered together; and by their being open or compact, regular or irregular, densely clothed with foliage, or only loosely covered.

Light and shade. The form of a tree or shrub is generally indicated by its outline against the sky; but that outline does not convey such a correct idea of the form as where the space enclosed by it exhibits both light and shade, which alone can give it the appearance of substance.

The capacities of different trees for receiving light vary according to the density of the masses of foliage. A compact round-headed tree, like the Sórbus Aria, will receive and reflect the light in one large mass; a tree or shrub, the general form of which is composed of numerous smaller masses, more or less separated from each other, will reflect the light in smaller masses; and a thin tree, which, in many parts, may be seen through, will not reflect the light from any part in a conspicuous manner. In proportion as the light is reflected from one side of a tree, the other side will appear dark; and a tree or shrub thinly clothed with foliage will appear to be equally in light and shade throughout. Most light and graceful trees are of this description; but the want of the beauty produced by light and shade is compensated by the wavy direction of the stem, which gives the idea of gentle motion, and by the variety and intricacy of the tuftings, outline, and disposition of the smaller branches, spray, and leaves.

The colours of trees and shrubs vary not only according to the kinds, but according to the season of the year, the climate, soil, situation, age, and other circumstances. In general, the colours of spring, when the tree is leafing, are more fixed and determinate than those of autumn, when it is losing its leaves; because, in the former case, it depends chiefly on the nature of the tree, while in the latter it is materially affected by the weather, and also by the soil. The birch, the leaves of which, in most soils, in a wet autumn, will die off of a yellow colour, in a dry autumn will assume a deep red; and, on a peat bog, birch leaves generally die off of a pale yellow, while on a granitic soil they generally assume a bright red or purple. On the side of the tree next the sun, the leaves of all trees are of a brighter colour than on the shady side. Those trees and shrubs which vary least in colour, whether in summer or autumn, are the evergreens; and those which vary most are the oaks, the acers, and the thorns.

The trunks of trees vary as much as their heads; not only naturally, according to the kind of tree, but accidentally, according to the circumstances in which it has been placed by nature, or by the hand of man. In general, a detached tree exhibits a trunk clothed with branches from the ground upwards; but trees grown in masses generally exhibit naked trunks to a considerable height. In some species, as in the pine and fir tribe, the length of naked trunk is great, in proportion to the size of the head; in others, as in the oak and