AIR-PLANTS are so called because they possess the power of living for a considerable time suspended in the air. It is however a mistake to suppose that there plants are naturally suspended freely in the air, and that such a situation is that in which they will thrive; they will only exist in air for a shorter or longer period, according to the species and to other circumstanced, but in the end they will perish. This arises from the fact that all plants require inorganic m well as organic constituents} and although those latter elements can be supplied from the air in the forte of carbonic acid, ammonia, and water, the former cannot. • There are two different tribes to which the name of Air-Planta has been applied ; of which one, containing the moss-like Tillandaia arneoides, which hangs in festoons from the branches of tram in the hot damp fortetts of tropical America, and the fragrant T. .riphioides, which adorns the balconies of the houses in Buenos Ayres, is called by botanists Bromeliacar ; the other, abounding in species of the most different nature and appearance, is named Orckidacar.
Till within a few years the cultivation of Air-Planta of the Orchis tribe was supposed to be attended with insuperable difficulties ; and of the many hundreds of beautiful species that are found in foreign countries, scarcely any were known in Europe, except from drawings, had descriptions, and imperfect dried specimens.
The native country of those curious plants is wherever a climate is found in which heat and moisture are in excels. Within the tropics in Asia, Africa, and America, in damp and shady forests, by the side of fountains, within reach Of the spray of waterfalls, perched upon the branches of trees, or clinging to rocks and stones by means of their long and writhing roots—creeping among moss, rearing their flowers in the midst of brakes and other moisture-loving tribes—in all such situations they are found in abundance. The princiied stations for them are the woods of Brazil and Peru, the lower mountains of Mexico, the West Indies, Madagascar, and the adjoining islands, and the whole of the Indian Archipelago; in Java alone nearly 300 species have been discovered.
The conditions under which Air-Planta, of the kind now described, naturally thrive are—I, high temperature; 2, diffused light, like that of a shady grove, and not direct solar light; 3, a great degree of dampness; and, 4, n perfect freedom from stagnant water round their roots : for on the trunks of trees or on stones and reeks no water can lodge, and all the moisture they receive must necessarily be in the form of vapour or of falling rain. And it is to circumstances of this nature that the gardener has chiefly to attend. Damp, shade, heat, and good drainage will be his object's; the three former will cause him no trouble, but the latter will require him to alter entirely his usual mode of cultivation. Instead of considering in what kind of soil his Air-Phtnts nro to be placed, ho will endeavour to dispense with soil, and to supply its place with bits of rotten wood, chopped moss in very email quantities, fragments of half-baked pottery, such as garden-pots, and the like.
Another point of great importance in the cultivation of these plants is, securing for them a season of repose. In their native climates, although they have no winter, they have a period of comparative rest from growth, and securing for them this repose whilst under culture is n great secret of success. It is ton knowledge of this, taken in conjunction with the circumstances before explained, that we owe the remarkable improvement that has taken place in the mode of cultivating these plants in Great Britain.
(Lindley, Observations in the Transactions of the Horticultural Society, voL i., New Series, p. 42, and the latter volumes of the Botanical Register.) (Ertrurry-i ; Oncertnnessi