stiffest part of the London clay. Probably every piece of cultivated ground, which contains a laburnum tree, produces each spring a plentiful crop of self-sown young trees, which come up without the least care or protection until destroyed in the process of weeding; yet the laburnum shows no disposition to take a place among the naturalised trees of our woods and hedges, although the seeds must often be carried there by birds. It is remarkable that many of our common vegetables, the cabbage, the asparagus, the sea-kale, the celery, are natives of our own shores, never growing spontaneously out of reach of the salt spray; and yet requiring, when transplanted into our gardens, no peculiarity of soil or treatment to enable them to support a vigorous existence. These are instances of plants to which our climate appears entirely congenial, and yet which seem as if they could not propagate themselves with us or spread, except under man's protection. Others, again, appear to require only to get a footing in a foreign soil to become established in it with extraordinary rapidity, even to the overmastering or expulsion of some of the indigenous inhabitants. When Australia and New Zealand were first colonized by Europeans, their flora presented an aspect of perfect strangeness, very few of the native trees or flowers belonging even to genera common to Europe. The seeds of some of our English weeds were, however, introduced, intentionally or accidentally, by the early settlers; and now the thistle covers the waste lands of Australia as it does in England, and the clover and the groundsel everywhere remind the Englishman of his far-away home, and have become as completely at home as the mustangs or wild-horses on the pampas of South America. In our own country a very remarkable instance of this rapid naturalisation has occurred in the case of the Elodea canadensis or Canadian water-weed; which, introduced not many years since into our canals from Canada, has now become such a pest in many places as seriously to impede the navigation. Other instances might be mentioned of foreign plants introduced with seed having in a very short time become common weeds in all cultivated land. Indeed, many of the species included in our handbooks of British plants are so entirely confined to arable land or to spots in the immediate vicinity of human dwellings, that it is impossible to say how many of them may be really indigenous to the soil, and how many naturalised aliens.

There is no doubt we have a great deal to learn as to the mode in which plants propagate themselves in nature, which may be of the utmost value to our gardeners. Every one is familiar with the fact of the apparently spontaneous appearance, in immense abundance, of plants in soil when subjected to certain farming operations, or on the sowing of some particular crop. Whenever a new railway cutting or embankment is made, some plant unknown in the neighbourhood is almost sure to appear, and either permanently

establish itself or again disappear after a few years. The "sowing" of land with lime is invariably followed by the appearance of a crop of white or Dutch clover. When certain kinds of wood are cut down, it is said that during the next year a particular species of moss will always be found covering the ground. Immediately after the great fire of London in 1666, the London Rocket (Sisymbrium Irio) sprang up in enormous quantities on the dismantled walls, but is now no longer to be found in the metropolitan district. The usual theory to account for this sudden appearance of new plants is the existence in the soil of large "stores of seeds" ready to germinate on the first favourable opportunity. In his Anniversary Address to the Linnean Society in 1869, Mr. Bentham, however, pointed out that if this explanation is the true one, it ought not to depend merely on theory, but would be capable of easy practical verification. He suggested whether a hitherto insufficiently acknowledged part in the rapid dissemination of plants may not be played by birds. The whole subject presents a wide field for further investigation, and must amply reward any one who takes up the inquiry, if endowed with the qualities of accurate observation and patient research.

Mr. Mongredien's Planter's Guide' deals chiefly with the introduction into this country of foreign trees and shrubs. Within the last twenty or thirty years the appearance of our lawns and plantations has been greatly changed by the number of new forms which have made their appearance. The stately Wellingtonia, the formal self-asserting "Puzzle - monkey or Araucaria imbricata, the massive Deodar and Cryptomeria, the elegant Pinus insignis and Cupressus Lawsoniana, are all still of too recent introduction to permit us to judge of what their effect will be when grown to their full stature. The number of cone-bearing trees from all parts of the world, perfectly hardy in this climate, is extraordinary; and, partly from their graceful shape, partly from the evergreen character of their leaves, the attention of cultivators has been perhaps too exclusively confined to them, while deciduous trees have been comparatively neglected. Recent experiments have shown that in this quarter also there is abundant room for an extension of our powers of domestication. In one of the London Parks least frequented by the upper ten thousand, that at Battersea, great success has attended the introduction, during the last few years, of half-hardy trees and shrubs, the precaution being taken of protecting their roots during winter by a layer of some substance impervious to frost. The French have paid more attention to the perfect naturalisation of half-hardy plants than we have done: notwithstanding the greater severity of their winter, species are grown by them out of doors which are never seen with us except in greenhouses; even as far north as Paris, the bamboo, for instance, is frequently met with in

gentlemen's gardens; and there is no doubt that many shrubs and herbaceous plants, which we never think of attempting to grow except under protection, might, with a very little care and attention, become permanent denizens of our gardens and shrubberies. Probably few are aware that the common Camellia will stand with impunity an ordinary English winter. Mr. Mongredien says that "if protected during the first two or three years after being planted out, and when once established, it proves in the climate of London quite as hardy as the common laurel, and blooms as profusely as in a conservatory. It is true that, from its habit of flowering early in the spring, the blossoms are sometimes damaged by the nipping easterly winds, but this occurs only in unfavourable seasons; and even if the tree never flowered at all, its lovely foliage would still make it one of the most beautiful evergreens of which our gardens can boast. A plant of the variety Donkelarii has stood out for twelve years in a garden at Forest Hill with a northern aspect, without the slightest protection during the severest winters, and now forms a good-sized bush, densely clothed with magnificent foliage. The Camellia ought to be planted out in every garden, and with a little attention for the first year or two, it would prove quite hardy, at least in the more southern counties, and each season it would increase in attractiveness."

The climate of the south of England is far more congenial to the introduction of foreign trees and shrubs than that of the northern counties, not from the greater severity of the winters in the north, for the minimum temperature of the year is often as low in Kent or Hampshire as in Yorkshire or Northumberland, but from the shorter and cooler summers. Many plants absolutely require a considerable period of high temperature to enable them to ripen their wood sufficiently to withstand the winter frosts, and especially to induce them to flower. In many parts of Scotland, however, the climate is as favourable to horticulturists as in any district of England. In the Duke of Sutherland's estate at Dunrobin, on the east coast of Sutherlandshire, Hydrangeas, myrtles, and other half-hardy plants, grow as freely and as unchecked out of doors as they do in Devonshire or Cornwall. The equalizing effect of the Gulf Stream on the temperature is no doubt the cause of this special immunity from frost. The proximity of the seacoast is not generally favourable to the growth of trees and shrubs, not so much from the saltness of the air as from the prevalence of high winds, which are very injurious to growing vegetation. Young and tender shoots which will bear a moderate amount of cold, will sometimes be scorched as if by fire by a tempestuous night.

Mr. Mongredien's book is intended as a repertorium of everything connected with the choosing, planting, and treatment of English and foreign trees and shrubs, and contains an immense mass

of information for any one whose tastes lie in this direction. Its defects are rather of omission than of commission. The plan promises a completely exhaustive treatment of the subject: in the first place we have an alphabetical list, with brief descriptions, of 621 trees and shrubs, selected as desirable for planting in the open air in this country; followed by a classification of them under a variety of headings, as to their height, their foliage, their time of flowering, the colour of their flowers, their fruit, their timber, and other points. It is illustrated by a number of very pretty woodcuts, of which we subjoin a specimen. The principle on which these 621 species

have been selected is not always obvious. Why, for instance, is our common Fuchsia (miscalled Fuchsia coccinea, as Dr. Hooker has shown) excluded, forming as it does the glory of every cottage-garden in the Isle of Wight and in Devonshire, the stems assuming almost

a tree-like character; or the Berberis aquifolium, which, with its glossy leaves and very early flowers, is so deservedly a favourite in every shrubbery? In the enumeration of winter-flowering plants we miss also the beautiful Forsythia, and several others which might have been mentioned. An exceedingly useful list is that of "species which thrive in the smoke of cities," in which Mr. Mongredien names the horse-chestnut, Ailantus glandulosa, Virginian creeper, almond, Artemisia abrotanum, Aucuba, Catalpa, Cydonia japonica, laburnum, fig, ivy, Cape jasmine, privet, Paulownia imperialis, Phillyrea media, plane, evergreen oak, Rhamnus Alaternus, sumach, flowering currant, Robinia pseudacacia (commonly called the acacia), Sophora japonica, and guelder rose; a very useful list to cultivators of suburban gardens, but again very incomplete. In London gardens the lilac is everywhere the companion of the laburnum; magnificent hawthorn-trees could be shown within two miles of Charing Cross; the roads in the suburbs are everywhere adorned in early spring with the beautiful light-green foliage of the lime; while the sides of the houses are gay in the summer with the gorgeous flowers of the hardy passion-flower, or the gigantic leaves of the Aristolochia Sipho; nor should the apple, the pear, and the cherry have been omitted, if it is only for the wealth of their flowers. It is worthy of remark that the smoke of an ordinary town is not nearly so destructive to vegetation as that poured forth from the chimneys of manufactories or chemical works. Flowers will be found to thrive in gardens in the very heart of London, which many a Lancashire gentleman would give almost any money to establish even in his greenhouses. Notwithstanding the deficiencies we have named, The Planter's Guide' is a book that should be in the hands of every one interested in the subject; and we hope it may be the means of attracting attention to the great value and importance of ornamental planting in improving the character of our lawns, shrubberies, and parks.

If we now turn from trees and shrubs to herbaceous plants, we enter on a still wider field, and one more within the reach of every lover of nature. Arboriculture, after all, must always be the pursuit of those only who have both money and space at their command; floriculture may be followed by every cottager, and even by every dweller in a town who has a window-sill at his disposal; and we doubt whether the latter does not derive the most pleasure from it. Although many of the favourite flowers of the last two or three generations will probably always hold a place in our gardens, and deservedly, yet the number of species that have been introduced of late years worth cultivating for their beauty, and within the reach of every one who possesses a flower-pot, is very large; and as a hand-book for this class of plants, though treating only of a section of them, plants especially adapted for rock-work, we can most