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Hoya (Named after Thomas Hoy once)

(named after Thomas Hoy, once gardener to the Duke of Northumberland, at Sion House). Honey Plant; Wax Flower. Including Centrostemma, Cyrtoceras, Otostemma, and Pterostelma. SYNS. Schollia, Sperlingia. ORD. Asclepiadeae. A genus comprising about fifty species of very ornamental stove scandent or decumbent shrubs, natives of Western Asia, tropical and sub-tropical Australia, but found in the greatest abundance in the Malayan Archipelago. Flowers medium or large, rarely small; corolla rotate. Leaves opposite, fleshy or coriaceous. Hoyas are very interesting and beautiful plants, producing handsome wax-like flowers. Most of them succeed better in an intermediate temperature than where it is very hot. They are not so well adapted for training on rafters, or and dry surface, as on a wall, or in a position where more moisture is present, such as that of a warm green-house or stove. H. carnosa is a fine species, and the one most frequently grown. It sometimes becomes attached to a wall, like Ivy, and grows freely when planted out at the base. H. bella and H. Paxtoni are slender-growing plants, requiring a little more heat. They are well adapted for culture in hanging baskets, or over pieces of dead tree fern, placed in the middle of pans. Propagation is generally effected by cuttings, or by layers. H. bella, however, succeeds best when grafted on a stronger-growing sort than it does on its own roots. Cuttings should be taken in spring, or later in the year, from shoots of the preceding summer's growth, inserted in soil composed of peat and sand, and plunged in bottom heat, inside a frame or under a bell glass. A slight shade and careful watering will be necessary. When rooted, shift into larger pots, using soil of a similar description, and stop the points of the shoots when growth is resumed. For propagation by layering, good-sized pieces should have a few of their leaves removed, and be layered in pots of soil until rooted. The plants may afterwards be grown on and repotted, according to their strength, in various-sized pots, or any of the strong-growing species may be planted out in rather rough peaty soil, care being taken to render the drainage efficient. Hoyas do not require much shade, nor an atmosphere too closely confined. They should be allowed to rest in winter, by keeping rather drier and in a lower temperature. The flower stalks should not be cut off, as the flowers of the next year are produced on them, as well as on the young wood, when it is growing well. Sometimes, when plants attach themselves to a moist wall, they do well even if the roots in the soil die away. The species described below are climbers, except where otherwise stated. H. australis (Southern).* fl. white, tinged with pink, with a Honeysuckle-like scent; disposed in deflexed umbels. October. l. obovate or sub-orbicular, coriaceous, deep green. Queensland and New South Wales, 1863. (B. M. 5820.) H. bella (beautiful).* fl. waxy-white, with a rosy-crimson centre; umbels many-flowered. l. small, opposite, dark green on the upper side. h. 1 1/2ft. India, 1847. (B. M. 4402.) H. Paxtoni closely resembles this in habit and appearance, but has less fleshy, more acuminate, and lighter green leaves, and pure white flowers with pink centres. Both species are of a dwarf, shrubby, slender habit, forming a drooping mass.

H. campanulata. See Physostelma Wallichii.

H. carnosa (fleshy).* Wax Flower. fl. pinkish-white; corolla fleshy, bearded inside; umbels pendulous, on short peduncles; pedicels pubescent. Summer. l. fleshy, oval-oblong, acuminated. Queensland, 1802. (B. M. 788, under name of Asclepias carnosa). There is a form of this species with variegated leaves. H. cinnamomifolia (Cinnamon-leaved).* fl. large; corolla pale yellow-green; rotate segments broadly-ovate, acute; leaflets of the staminal crown deep purple blood-colour, ovate, acute, thick, fleshy. July. l. opposite, on short, very thick petioles, large, ovate, slightly peltate, acuminate, thick; three central nerves very conspicuous. Stem long, branched, twining. h. 10ft. Java, 1847. (B. M. 4347.) H. coriacea (leathery). fl. brownish-yellow, produced in large umbels. summer. l. ovate-acute, coriaceous, dark green. Manila, 1838. (B. M. 4518.) H. coronaria (crowned). fl. yellow. November. l. oval, acute, with recurved edges, coriaceous, villous beneath. Java. 1856. (B. M. 4969.) H. Cumingiana (Cuming's).* fl. greenish-yellow or white, with a coronet of rich purplish-brown; umbels axillary, short. Spring and summer. l. closely packed, flat, sessile, cordate, slightly downy beneath. Malay Archipelago. (B. M. 5148.) H. globulosa (globular).* fl. pale straw or cream-colour, disposed in globose umbels; corona pink at base. April. l. oblong, coriaceous, rounded at the base, acuminate at the apex, more or less hairy. India, 1880. (G. C. n. s., xvii. 741.) H. imperialis (imperial).* fl. reddish-brown, very large, about 3in. across, waxy; umbels 8in. to 9in. in diameter, and eight to ten-flowered. June. l. 6in. to 9in. long, slightly tomentose, light green. Borneo, 1847. A very noble plant. (B. M. 4397.) H. lacunosa (furrowed). fl., corolla greenish-yellow, rotate; inner surface covered with velvety hairs; peduncles interpetiolar, solitary, usually shorter than the leaves, bearing a flattened umbel of numerous flowers. March to June. l. opposite, elliptic-lanceolate, acuminated, marked above with a depressed midrib and a few horizontal depressed veins; petioles thick, short. Branches terete, throwing out roots from various points. Indian Archipelago, 1854. (B. M. 4826.) H. l. pallidiflora (pale-flowered). fl. almost colourless. l. broader than in the type; nervation obsolete. Java. (B. M. 5272.) H. linearis (linear).* fl. white, in a sessile, terminal, lax umbel. Autumn. l. shortly stalked, cylindrical, sub-acute, deeply grooved beneath, dark green. Himalaya. A charming plant, with slender pendulous branches, suitable for cultivation in hanging baskets.

H. multiflora. This is the correct name of the plant described in this work under the name of Cyrtoceras multiflorum (which see). H. ovalifolia (oval-leaved). fl. bright yellow, with a red corona; produced in large umbels. Summer. l. fleshy, narrowly oval, about 6in. long, rolled back at the edges, dark green. India, 1840. (L. & P. F. G. 23.) H. pallida (pale).* fl. pale yellow or straw-colour, with a pink corona; very fragrant, disposed in moderate-sized umbels. Summer. l. fleshy, ovate, dark green. India, 1815. (B. R. 951.) H. Paxtoni. See H. bella.

H. Pottsii (Potts's).* fl. pale yellow, slightly downy, fragrant; corona rather purple in the centre; umbels globose. l. cordate, acuminated, with a rusty stain partly spread over them, pale whitish beneath. India, 1824. (B. M. 3425.) H. purpureo-fusca (purplish-brown-flowered). fl. purplish-brown, produced in large umbels. September. l. ovate, slightly acuminate, fleshy, dark green. Java, 1849. (B. M. 4520.) H. Shepherdi (Shepherd's).* fl. small; corolla delicate white and rose-colour; umbels about 2in. in diameter. June. l. 2in. to 6in. long, four lines wide, shortly acuminated at the apex, dark and channelled on the upper side, paler and semi-terete beneath; they are, as it were, geniculated at the apex of the short terete petiole, or bent down suddenly at an angle, and thus become pendent. h. 3ft. Sikkim-Himalaya and Khasia, 1860. A very remarkable plant. (B. M. 5269.) H. trinervis (three-nerved). fl. pale greenish-yellow, slightly scented; corona whitish, with a yellowish ting in the centre; umbels globose. Summer. l. variable in size, oblong, sharply acuminated, light yellowish-green above. China, 1824.