AERATION. The exposure of the soil to the free action of the air, as essential to the growth of plants.
AERIDES (from aer, the air; in reference to the power the species have of deriving their sustenance from the atmosphere). ORD. Orchideæ. An extensive genus of epiphytal orchids, confined to the tropics of the Old World, including many large and showy-flowered species. The majority of them are extremely handsome. The thick fleshy leaves are noteworthy for their characteristically distichous arrangement—that is to say, they are arranged in two opposite rows. They are usually truncate at the apex, and for the most part deeply channelled down the centre, but in some species terete or nearly cylindrical. All of them throw out large fleshy roots from various parts of their stems, by which they absorb the moisture from the atmosphere; and, in order to grow them successfully, they must be fixed upon blocks of wood. But this method should be adopted only whilst the plants are young, as it is almost an impossibility for the cultivator to maintain a sufficient amount of atmospheric moisture to meet their requirements; and, unless this is managed, the leaves will shrivel and fall off, leaving only a few at the extremity. Therefore, as soon as the plants are established upon the blocks of wood, let them be removed and potted. Fill the pot three parts full of broken potsherds and lumps of charcoal, and then use nothing, but clean, living sphagnum, placing a few roots in the moss and leaving the others free. By this means a greater amount of moisture can be supplied to them, and thus beautiful and symmetrical specimens obtained. The Aerides are easily grown into handsome plants, which usually bloom profusely, and thus recommend themselves to all who cultivate orchids. From early spring until the end of September they should be treated liberally with water, at the same time taking care never to wet the flowers. After the above-named time, a gradual diminution in the water supply to the roots should take place; and the atmosphere, too, should be less densely charged with moisture. But drought should never be carried far enough to cause the leaves to shrivel, for, if this is done, the uniformity of the specimen is marred; and, although we are quite willing to admit the possibility of the plants producing a greater quantity of flower spikes after a thorough shrivelling, we prefer to advocate the system that gives a fair amount of flower coupled with good leafage. As before remarked, the Aerides are peculiarly eastern, and therefore are usually classed amongst the orchids which require the hottest houses. This is, in one sense, correct; yet they do not require the great amount of heat which many imagine, and which has, until recently, been given them. They must not, therefore, be excluded from the amateur's collection of orchids. During the winter season many of the species may be kept in a temperature of 58deg. to 60deg.; whilst during the growing season the temperature may run up by sun heat without limit, so long as a free circulation of air and a sufficiency of moisture are secured. The following status of temperature may be observed: In spring, from 65deg. in the night, to 70deg. or 80deg. by day; in summer, from 70deg. in the night, to 80deg. or 85deg. through the day; in winter, about 60deg. night, and 65deg. day.
A. affine (related).* fl. delicate rose, produced, in great profusion, on branching spikes, which are sometimes 2ft. in length, and continue in bloom two or three weeks; the sepals and petals equal, rounded at the apex; the lip is sharply rhomboid and three-lobed, with a short spur. l. light green, about 1ft. long. h. 3ft. A very handsome species from India, forming an excellent exhibition plant.
A. a. superbum (superb).* An improved variety, with larger and richer coloured flowers, and more compact habit.
A. Brookii (Sir A. Brooke's).* fl. purple and white; labellum bright purple; sepals and petals white, very fragrant. l. very ornamental, of a glaucous (milky green) hue. Bombay. This species, although one of the handsomest, is very rare.
A. crassifolium (thick-leaved).* This is a dwarf, densely-habited plant, with broad, thick, purple-dotted obliquely-bilobed leaves. The flowers, which are borne on long and drooping spikes, are bare—larger than those of A. falcatum, which they resemble in form, and have the segments tipped with rich purple or amethyst, the centre or throat of the flower being ivory-white. Compared with A. falcatum, the spur is here bent under at an angle, while in that plant it is straight; the side laciniæ of the lip are much broader and shorter in the present plant, and the two keels on the lip here stand close together at the base, and become divergent, whilst in falcatum they are distant at the base, and become convergent near the middle of the lip. This species is described as being the best in the genus. It may be grown near the glass, suspended in a basket. Burmah, 1877.
FIG. 34. FLOWER OF AERIDES CRISPUM.
A. crispum (curled).* fl. white, suffused with purplish rose, nearly 2in. in diameter; sepals and petals ovate, acute; lip three-lobed, the middle lobe being very large, toothed at the base, and fringed at the margin; the horn-like spur is slightly incurved; racemes ascending, more than double the length of the leaves, many-flowered. l. deep green, flat and broad, blunt at the ends, and two-lobed, about 4in. or 5in. long. Bombay, 1840. Lasts a long time in beauty. See Fig. 34.
A. c. Lindleyanum (Lindley's). A robust-growing variety, producing a large, much-branched panicle of flowers; sepals and petals white; lip large, bright rich rose-coloured.
A. c. Warneri (Warner's).* The leaves are smaller, and more slender than in the species; the sepals and petals are white, with a soft, rich, rose-coloured lip.
A. cylindricum (cylindric).* fl. white and pink, as large as those of A. crispum; sepals and petals crispy. l. elongate, subulate, terete, 4in. to 6in. long. East Indies. A very rare and distinct species. SYN. A. vandarum.
A. dasycarpum (thick-fruited). fl. brownish, rosy. India, 1865.
A. dasypogon. See Sarcanthus erinaceus.
A. difforme (deformed). fl. green and brown. India, 1865.
A. Dominiana (Dominy's).* This is a garden hybrid between A. Fieldingii and A. affine, with the colour of the former, but markings and shape of the latter. Very rare.
A. falcatum (sickle-leaved).* fl. sepals and petals white, dotted with reddish crimson, and tipped with soft rose; lip white at the sides, with a rosy-crimson centre; spur short, parallel with the lip; racemes pendulous, many flowered. l. closely set upon the stem, peculiar blue-green, coriaceous, obtuse and mucronate. This species is very closely allied to A. crassifolium. SYN. A. Larpentæ.
FIG. 35. AERIDES ODORATUM.
A. Fieldingii (Fielding's).* The Fox-brush Ærides. fl. white, numerous, large, beautifully mottled with bright rose colour; the much branched racemes are 2ft. to 3ft. long, and continue blooming three or four weeks. l. 8in. to 10in. long, in some plants light green, and in others dark green; long, broad, thick, and fleshy, obliquely two-lobed at the apex. h. 3ft. to 4ft. Assam.
A. Houlletianum (Houllet's).* fl. sepals and petals buff, shading off into cream white at the base, with a purplish eye-spot at their tips; lip white; front part dark purplish, with some lines of the same colour on the sides; on densely crowded spikes. l. and growth similar to A. virens. Cochin China. SYN. A. Mendelii.
A. japonicum (Japanese).* fl. white, with the lateral sepals slightly barred with brown purple; several on the pendent racemes; lip purple, spotted, marked with a dark violet central ridge. l. short, linear-oblong, obtusely bilobed. Stems short, about 4in. high. A pretty cool house species from Japan, 1862.
A. Larpentæ (Lady Larpent's). Synonymous with A. falcatum.
A. Lobbii (Lobb's).* fl. white in the centre, slightly tinted with blush-rose towards the outside, somewhat spotted with violet; lip marked with a whitish central bar, and stained with a deep violet on either side; on long, dense, cylindrical, pendent spikes. l. ligulate, obliquely two-lobed at the apex, thick and fleshy in texture, about 18in. long, and of a light green hue. Moulmein, 1868. This elegant plant, of which many distinct varieties are in cultivation, is one of the most delicate of the genus.
A. maculosum (spotted). fl. large, with obtuse pale rose-coloured sepals and petals, which are spotted with purple; lip flat and undivided, bluntly ovate, and of a deep rosy-purple; racemes pendulous, proceeding from among the upper leaves, somewhat lax and branching. l. ligulate, thick, and fleshy, obtuse at the apex, 8in. or 9in. long, dark green. A somewhat slow growing species, with a rather stiff, dwarf habit. Bombay, 1840.
A. m. Schrœderi (Schrœder's).* fl. very delicate white, tinged with lilac and spotted with rose; labellum beautiful rose coloured. l. dark green, 10in. long. h. 18in. East Indies. A very free growing and handsome variety, superior to the species, but rare in cultivation.
A. Mendelii (Mendel's). Synonymous with [A. Houlletianum.]
A. mitratum (mitred).* fl. waxy-white; lip violet coloured, on numerous dense erect racemes. April. l. cylindrical, attenuated, about 2ft. long, dark green. Moulmein, 1864. A rare but elegant species.
A. nobile (noble).* fl. sepals and petals white tipped, and spotted with bright rose; lip three-lobed, the side lobes creamy yellow, and the middle lobe slightly bifid at the apex, white, dotted with rose-purple, very fragrant; racemes 2ft. to 3ft. long, pendulous, much branched, many flowered. l. strap-shaped, obliquely emarginate at the apex, light green, slightly spotted with brown. Not unlike A. suavissimum, but with larger and better coloured flowers, and more robust growth. East Indies.
A. odontochilum (tooth-lipped). h. 2ft. Sylhet, 1837.
A. odoratum (fragrant).* fl. sepals and petals creamy and white, tipped with pink; lip cucullate, with even side lobes, the middle lobe being ovate and inflexed, the spur conical and incurved, of the same colour as the sepals, very fragrant; racemes longer than the leaves, many-flowered, pendulous. l. oblique, obtuse, mucronate at the apex, and dark green. East Indies, 1800. See Fig. 35.
A. o. cornutum (horned). fl. pink and white. Distinct.
A. o. majus (greater).* Like A. odoratum in growth, but with larger and longer spike of flowers.
A. o. purpurascens (purplish).* A very robust variety, with broad dark green leaves and massive spike of large flowers, which are white, tipped with bright pink.
A. pachyphyllum (thick-leaved). fl. light crimson lake; spur and column white, the small laciniæ of the blade of the lip on front part of spur painted with more or less warm purple (these laciniæ are just as insignificant as the spur is preponderant); raceme short, few-flowered. l. fleshy, short; apex obtuse, and unequally two-lobed. Burmah, 1880.
A. quinquevulnerum (five-wounded).* fl. fragrant; sepals and petals obtuse, white, marked with five reddish crimson blotches, and tipped with purple; lip cucullate and funnel-shaped, the side lobes being erect and the centre lobe oblong, incurved and serrated, of the same colour as the sepals; spur conical, green, large; racemes longer than the leaves, pendulous, and many-flowered. Late summer and early autumn. l. ligulate, about 12in. long, tightly clasping the stem at the base, obliquely mucronate at the apex, bright shining green. Philippines, 1838.
A. q. Farmeri (Farmer's).* A very rare variety of the above, with similar habit, but the flowers are pure white throughout, and fragrant.
A. Reichenbachii (Reichenbach's).* fl., sepals neatly striped (not blotched); lip deep orange colour; racemes densely crowded. Borneo, 1858. A very rare species.
A. roseum (rose-coloured).* fl., sepals and petals narrow, acute, pale rose colour, with darker spots; lip flat, entire, and acute, of a bright rose, freckled—like the sepals and petals—with spots of a darker hue; raceme pendulous, dense, and many-flowered, upwards of 1ft. in length. l. coriaceous, recurved, and channelled above with a blunt two-lobed apex. Moulmein, 1840. As this does not root freely, it requires less moisture than any other species.
A. r. superbum (superb).* A fine variety, with stronger growth and larger and richer-coloured flowers. The spikes of this, as well as the typical species, are apt to die off if much water is given.
A. rubrum (red). A synonym of Sarcanthus erinaceus.
A. suavissimum (sweetest). fl. sepals and petals obtusely ovate, white, tipped or tinged throughout with deep lilac; lip three-lobed, pressed to the column, the side lobes being oblong and denticulate, the middle lobe linear and bifid, the whole lip being of a pale lemon colour, and the spur rosy-eyed; the numerous racemes are half pendulous and branched, bearing a profusion of deliciously fragrant flowers. l. flaccid, about 10in. long, light green, profusely freckled with brown dots. Malacca, 1848. There are one or two varieties.
A. tesselatum (chequered). fl. lined and streaked with green, white, and purple. East Indies, 1838. A scarce species.
A. testaceum (testaceous). A synonym of Vanda testacea.
A. Thibautianum (Thibaut's). A synonym of Saccolabium Huttoni.
A. vandarum (Vanda). A synonym of [A. cylindricum.]
A. virens (vigorous). fl. deliciously fragrant; sepals and petals ovate, obtuse, soft white, tipped with rosy-purple; lip large; side lobes toothed at the apex, white, dotted with crimson; middle lobe bearing a red inflated tongue; racemes long, drooping, many-flowered, commencing to bloom early in April, and lasting until July. l. broad, oblique, rounded at the apex, with a depression in the centre, and very bright green, about 8in. long.
A. v. Ellisii (Ellis's).* fl. sepals and petals large, white, suffused with rose, and tipped with amethyst; the lower sepals very round and broad; lip large; side lobes white, beautifully freckled towards the base, with short lines of amethyst; middle lobe broad, and deep rich amethyst in colour; spur stout, curved upwards, and tipped with brown; racemes about 18in. long, bearing generally from thirty to forty, or more, large flowers. l. pale green. A splendid variety.
A. Wightianum. See Vanda testacea.
A. Williamsii (Williams's).* fl. delicate pinkish white, produced in great abundance; spikes 2ft. to 3ft. long, and branched, l. broad, dark green, drooping. A very scarce and pretty species.
AEROBION. See [Angræcum.]