Ada.—Cool-house genus from Colombia. Leafy evergreen plants with racemes of orange-scarlet flowers. Ada aurantiaca is almost the sole representative of the genus in gardens, and should be grown even in the smallest collections.
Aëranthus. See Angræcum.
Aërides.—A large genus of evergreen Orchids with distichously arranged, leathery, green leaves, the stem producing air-roots freely. Natives of India, the Malay Archipelago, and other parts of that region, extending to Japan.
All the species of Aërides may be grown in pots, crocked from one-half to two-thirds of the way up, the old stems of the plants, when long, being placed in the pots before the crocks are filled in. The surface should be of good living Sphagnum-moss, and the plants should be liberally watered from the end of February or beginning of March until autumn, when the supply of water should be restricted according to the condition of growth of the plants. Those which have finished their growth and are not showing new leaves in the centre should be given the least supply, but it is not advisable to dry any off completely, unless for some reason they have to be kept comparatively cool throughout the winter, when they are safest if kept tolerably dry. The smaller species may be grown in baskets with advantage when convenient—indeed, the true epiphytal character of the whole genus would suggest that method as the better, but experience has proved that they may be equally well grown in pots. The warm house, or warm end of the intermediate house, suits all the species, but A. japonicum may be grown in the cool house. Most of the species have white and rose-coloured flowers, and they are very fragrant.
A. odoratum, one of the oldest of garden Orchids, is one of the best and most free-growing species. A. crispum, A. crassifolium, A. Fieldingii, A. Houlletianum, A. falcatum, A. Lawrenciæ, A. multiflorum in its many forms, A. quinquevulnera, A. suavissimum, and A. virens are the best for amateurs.
A. cylindricum and A. Vandarum have terete leaves like Vanda teres, the former with white flowers, having a fleshy yellow and red lip, and the latter, which is more membraneous in substance, being white. Although often confused with each other in gardens, there is little resemblance between these two species.
Aganisia.—This genus thrives best in Orchid pans in the intermediate house, in the ordinary compost used for epiphytal Orchids, with an addition of leaves. Place the plants in a moist situation.
A. cærulea is of trailing habit, and has blue and white flowers. A. ionoptera is white and purple, and A. lepida white.
Angræcum.—A large genus chiefly from Africa and Madagascar, and requiring similar treatment to Aërides. Botanists have divided the genus into Aëranthus, Listrostachys, Mystacidium, &c., but for garden purposes the one generic title suffices. The flowers of nearly all the species are white and fragrant, many of them being furnished with long, greenish spurs.
A representative selection could be made with A. arcuatum, A. Ellisii, A. Humblotii, A. infundibulare, A. Kotschyi, A. modestum, A. Scottianum, A. superbum (eburneum), and A. sesquipedale, the last-named Madagascar species being the finest of the genus.