506

THAT IS SCARCELY TRUE.

Apples and Pears, and seeds of Strawberries, Raspberries, Gooseberries, and Currants, always selected from the finest varieties cultivated in England. It is, moreover, entirely at variance with the experience of the great Belgian fruit growers. (See De Jonghe on raising Pears from seed in the Gardeners' Chronicle, 1855, p. 21.)

CHAPTER XIX.

OF RESTING.

A GARDENER is said to rest a plant when he exposes it to a condition in which it cannot grow, aud which is analogous to its winter state. For many parts of gardening, especially what relates to forcing, and the management of exotic plants, this is a subject of the first importance.

If we look over the different climates of the world, we shall find that in each there are a season of growth, and a season in which vegetation is more or less suspended; and that these periodically alternate, with the same regularity as our summer and winter. I do not know that there is in nature any exception to this rule for even in the Tierra templada of Mexico, where it is said that, at the height of 4000 to 5000 feet, there constantly reigns the genial climate of spring, which does not vary more than 8° or 9°, intense heat and excessive cold being alike unknown, and the mean temperature varying from 68° to 70°, we cannot suppose that, even in that favoured region, a season of repose is wanting; for it is difficult to conceive how plants can exist, any more than animals, in a state of incessant excitement. Indeed, it is pretty evident that these countries have a period when vegetation ceases; for Xalapa belongs to the Tierra templada, and we know that the Ipomoea purga, an inhabitant of its woods, dies down annually like our own Convolvuli. We also know that Jonquils, Hyacinths, and Tulips when grown in the Bahamas, where they are unable to take the rest which is natural to them, refuse to flower.

But, although all plants have naturally a season of repose, their winter is not in all cases cold. In the topics it is marked

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PERIODS OF RESTING

by coolness and dryness, while the summer is rainy and very hot; and in extra-tropical countries the two seasons vary in their character, according to latitude and local circumstances.

In some parts of Persia, Armenia, and Mesopotamia, the summer heats are excessive, while the winters are rendered cold by the proximity of mountains. Bagdad is described as having a cold winter, because of the proximity of the mountains of Koordistan; yet its heats are intense: in August, 1819, the thermometer stood at 120° in the coldest parts of the house, and at 108° at midnight in the open air. This was preceded by heavy rains, which raised the Euphrates 7 feet above the ordinary level: the whole country was like a vapour bath, and multitudes of persons dropped down dead: twenty-two in three days in a single caravan. In the northern provinces of Mexico the winters are of German rigour, while the summers are those of Naples and Sicily; the Tierra fria of its southern provinces has however a very different climate, the mean heat of the summer being 76°, and the winters so mild that the thermometer only occasionally falls below 32°.

At the Cape of Good Hope there are districts in which the period of wet is long and very severe; and many of the favourite flowers of our gardens are produced by those districts. The Karroos are plains of great extent, destitute of running water, with a soil of clay and sand, coloured like yellow ochre by the presence of iron, and lying on the solid rock. During the dry season the rays of the sun reduce the soil nearly to the hardness of brick: Fig-Marigolds, Stapelias, and other fleshy plants, alone remain green; nevertheless, the bulbs and tubers of Irids and other plants are able to survive beneath the sunscorched crust, which appears indeed to be necessary to their nature. But in the wet season these bulbs are gradually reached by the rain; they swell beneath the earth; and at last develope themselves so simultaneously that the arid plains become at once the seat of a charming verdure. Presently afterwards, myriads of the gay flowers of Irids and Mesembryanthemums display their brilliant colours: but in a few weeks the verdure fades, the flowers disappear, hard dry stalks alone remain; the hot sun of August, when in those latitudes the

IN DIFFERENT COUNTRIES.

509

days begin to lengthen, completes the destruction of the few stragglers that are left, the Karroo again sinks into aridity and desolation, and the desert reappears. What succulents survive are covered with a grey crust, and derive their nourishment only from the air. In other parts of the Cape of Good Hope the mean range of the thermometer in winter is 48° to 93°, with cold rain, while that of the summer is from 55° to 96°, with dry days and damp nights.

In the Canaries we have the season of growth from November to March, when rains fall like those of Europe, and the mean temperature is 66°; the period of rest is April to October, when it never rains, and the mean temperature is 73°.

In Brazil the seasons are thus described by Mr. Caldcleugh:-"The summer begins about the months of October or November, and lasts until March or April. This is the wet season; but the rains by no means descend from morning till night, as in some other tropical countries, but commence generally every afternoon about four or five o'clock with a thunderstorm. The heaviness of the rain can only be conceived by those who have been in these latitudes. This fall naturally arrests the sea breeze, and the succeeding night is dark and cloudy. Formerly these diurnal rains came on with such regularity that it was usual, in forming parties of pleasure, to arrange whether they should take place before or after the storm. During this period of the year there is seldom, if ever, a deposition of dew. From April until September very little rain falls; vegetation almost stops, and, to the eye of every one who has not just arrived from Europe, a wintry appearance is discernible. The land and sea breezes do not succeed each other with the same regularity, and are, besides, more frequently disturbed by violent gusts from the S. W., imagined to be the tails of those destructive winds, the Pamperos of the River Plate. The nights are beautifully clear; Venus casts a shadow, and the southern constellations are seen in all their beauty. The dews, as might be expected, are at this season very copious." (Brande's Journal, No. 27. p. 41.)

The periods of rest and activity in the vegetable world are, however, not always evident. The vegetation of the primitive forests of Brazil,

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ANNUAL REST IS UNIVERSAL.

writes Aug. de St. Hilaire, is in a state of constant activity. The winter is only distinguished from the summer by a changed green of the leaves, and if some trees lose their leaves it is only to be immediately replaced with new ones. In some districts, however, the trees become leafless every year. This happens when the rains, which endure for six months, suddenly cease, which takes place in February, and the heat increases gradually till June. In this latter month the trees are almost leafless, but in August again, before the rain commences, the buds have again expanded, and the trees are covered with leaves. The cause of this fall of the leaf is no doubt owing to the dryness of the soil, but it can only occur in some exposed districts of the primitive forests, as in most cases the trees are found on the borders of great rivers and on naturally damp soils, where the earth into which they strike their roots is never dry.-Treviranus.

In other parts of the tropics the seasons of growth and rest are equally marked. In Ava, during the rainy season, which lasts from May to October, the mean temperature varies from 78° to 91.5°; while, in the dry season, from November to April, it falls to from 63° to 80°. At Calcutta, in the growing season, from April to October, fifty-eight inches of rain commonly fall, with a mean temperature of 79° to 86°; while during the season of rest, from November to March, there is not perhaps an inch of rain, and the thermometer sinks to from 66° to 80°. At this time vegetation is said, in such countries, to "labour under a deadly languor; but one night's rain converts an arid plain into a verdant meadow."

In most of the West India Islands situated under the tropic of Cancer, there is said not to be much difference in the climate, so that accurate observations made on any one of them may be applied with little variation to them all. Malte Brun gives the following sketch of their seasons. "The spring begins about the month of May; the savannas then change their russet hue, and the trees are adorned with a verdant foliage. The periodical rains from the south may at this time be expected; they fall generally about noon, and occasion a rapid and luxuriant vegetation. The thermometer varies considerably; it falls sometimes six or eight degrees after the diurnal rains, but its medium height may be stated at 78° Fahrenheit. After these showers have continued for a short period, the tropical summer appears in all its splendour.