Dipladenia
(from diploos, double, and aden, a gland; referring to the presence of two gland-like processes on the ovary). ORD. Apocynaceae. Very ornamental stove evergreens. Flowers usually rose or purple, showy. Leaves opposite, entire. Among stove twiners, there are few more deserving of general cultivation than these, as the large flowers of some of the species and hybrids are unrivalled for brilliancy of colour, especially if the plants are allowed free root room, in a prepared border. They are also well adapted for exhibition purposes, in which case it will be necessary to cultivate in large pots, to admit of removal. When in flower, and well grown, Dipladenias, in either of these positions, must be classed amongst the most beautiful of stove plants.
Propagation is effected by cuttings of the young shoots that are produced when the plants commence new growth, in spring. These, or single eyes, should be inserted in a compost of equal parts sand and peat, covered with a bell glass, and placed in a brisk bottom heat. Roots will soon be emitted, and the young plants may then be transferred to separate pots, grown on, and shifted into larger sizes as required.
After - Cultivation. This will consist chiefly in supplying plenty of heat and moisture in the early part of the season, and in thoroughly ripening the main growths in autumn for the succeeding year. A suitable compost is fibry peat, broken up roughly for use, with sufficient silver sand added to insure the free passage of water. Drainage must also be efficient, as few flowering subjects show the effects of a waterlogged soil quicker than do these. Young plants should be grown on without stopping, and be supported by a stake until of sufficient size to be placed on a trellis. This is best made of small galvanised wire, and a conical or globular form is most suitable. If intended for planting out, to train on the roof of a stove--a position best suited for showing the flowers of Dipladenias--the trellis will be unnecessary, as the plants may be trained upright until established, and then placed out permanently. If a little bottom heat can be obtained, it will be of material assistance. The flowers are produced in profusion all the latter part of the summer, on the wood of the current year. Nearly all this should be removed when the flowering season is over, unless required for main shoots to cover the trellis. Dipladenias should be kept warm and in a moderately dry condition when at rest in winter, gradually introducing more moisture to start them in spring. Plenty of heat and frequent syringings, in early summer, will encourage the production of good flowering wood. The plants are subject to the same insect pests as many others grown in the high. temperature of a stove. When insects are detected, sponging the leaves and stems will prevent their increase, and is the best method of destruction.
D. amabilis (lovely).* fl. rosy-crimson, borne in clusters, very large, 4in. to 5in. in diameter; petals very round and stiff. May to September. l. shortly stalked, oblong-acute. h. 10ft. A very fine hybrid between D. crassinoda and D. splendens. (F. M. 309.) D. amoena (pleasing).* fl. pink, suffused with rose, somewhat resembling D. splendens, but much finer; petals round, stiff, and not reflexed. l. oblong-acuminate. Garden variety. This valuable plant flowers as freely as D. amabilis, and has better foliage than that plant.
D. boliviensis (Bolivian).* fl. white, about 2in. across, with a golden-yellow throat; racemes sub-terminal or axillary, three or four-flowered. l. oblong, acuminate. Stems slender. Bolivia, 1866. A very pretty small growing species. (B. M. 5783.) D. Brearleyana (Brearley's).* fl. opening pink, and changing to the richest crimson, very large. l. opposite, oblong, acute, dark green. A garden hybrid, of great beauty, and of the most floriferous character. D. carissima (choicest).* fl. of a soft delicate blush-pink, with an open throat, marked opposite the centre of the oblique limb-segments by radiating lines of bright rose, about 5in. in diameter. Garden variety. for which we are indebted to Mr. Wm. Bull. (F. & P. 1879, 502.) D. crassinoda (thick-jointed). fl. rose-coloured, of a very lovely shade. l. oblong-lanceolate. h. 10ft. Rio Janeiro. An old and well-known stove plant, now superseded by more showy sorts. SYN. D. Martiana. (B. R. 30, 64.) D. c. Houtteana (Houtte's). An improved variety of the preceding, with beautiful rose-coloured flowers, having an orange-coloured throat. D. delecta (choice). fl. of a very pretty shade of rosy-pink. finely formed, and of good substance; mouth encircled with deep rose and shaded with violet, and the light throat shaded with yellow. Garden variety. D. diadema (diadem).* fl. of a soft pink colour, suffused with rose, the mouth encircled with deep rose, of large size and excellent form. Garden variety. D. Harrisi (Harris's). A synonym of Odontadenia speciosa. D. hybrida (hybrid).* fl. of a flaming crimson-red, freely produced. l. large, stout, bright green. A beautiful garden variety, but rarely seen. D. insignis (remarkable).* fl. rosy-purple, bold. A stout-growing garden variety, with very strong foliage. See next page, Fig. 675, for which we are indebted to Messrs. Veitch and Sons.
D. Martiana (Martius's). A synonym of D. crassinoda. D. nobilis (noble).* fl. changing from rosy-purple to orange-red, large. A very handsome, free-growing, garden variety. (G. C. 1847, 748.) D. ornata (adorned). fl. of a rich crimson colour, beautifully suffused with violet, large. Garden variety.
D. Regina (Queen).* fl. blush on first opening, and afterwards changing to a most delicate flesh-colour, the throat being suffused with rose. An early-flowering variety, of neat growth and remarkably free habit. D. rosacea (rosy). fl. soft rosy-pink, suffused here and there, and also bordered, with a deeper and richer shade of the same colour; throat yellow, marked with a bright rose ring at the mouth. Garden variety. D. splendens (splendid). fl. white, suffused with pink, borne on spikes that keep on extending for months. Organ Mountains. A species with broad foliage and stout shoots. SYN. Echites splendens. (F. d. S. 1, 30.) D. s. profusa (profuse).* fl. rich carmine, 5in. in diameter, produced abundantly in bunches from the axils of the leaves, and lasting a long time in perfection. l. oblong, acuminate. Garden variety.
D. s. Williamsi (Williams's). fl. with a deep pink throat. Raised from D. splendens, on which it is a decided improvement, flowering more freely.