DIPLADENIA (Greek, double gland, referring to the two glands of the ovary, which distinguish this genus from Echites). Apocyndceae. A charming genus of coolhouse twiners, mostly from Brazil, with large, showy more or less funnel-shaped fls. having a remarkable range of color, rarely white or dark red, but especially rich in rosy shades and with throats often brilliantly colored with yellow. The buds, too, are charming. The genus is fully as interesting as Allamanda, which belongs to another tribe of the same order. Other allied genera of great garden interest are Echites, Ontadenia, Mandevilla and Urechites. Some species are naturally erect bushes, at least when young, and
many can be trained to the bush form. The group is a most tempting one to the hybridizer. An all-yellow flowered kind is desirable. Many names appear in European catalogues, but they are badly mixed. as the genus greatly needs a complete botanical revision. Very many pictures are found in the European horticultural periodicals. Several prizes for American seedlings have been taken at Boston, by Geo. McWilliam, Whitinsville, Mass., who has given a full account of his cultural methods in Gardening, 5:18 (1896).
Although Dipladenias are natives of the tropics, they grow at high altitudes, and it is a mistake to keep them in close, steaming hothouses, as many gardeners do in the Old World. The writer has kept them in a house whose temperature was never above 50° F., and frequently went down to 40° on winter nights. Cuttings should be rooted in winter, and the young plants planted outdoors during the summer, being careful not to bury the crowns deep in the soil. They can endure 5 degrees of frost without losing their foliage, but even after 7 degrees of frost and complete loss of foliage, the plants have been lifted, brought into the greenhouse, and flowered with success. A good specimen will have 50-80 open fls. at one time. Tufts of fern root are excellent for potting soil, with some sharp sand added. A fine specimen may be grown in a pan 2 ft. across and 9 in. deep. Plants never need shading. In late fall, as the nights get cooler. the water supply may be gradually reduced until the middle of November, when water is used sparingly until it is desired to start the plants into fresh growth. For points concerning training and pruning, consult Gn. 5:18.
Few tropical plants excel the Dipladenias as green house twining plants, their handsome sprays of flowers being produced in profusion from May to November,
when well grown. The usual method of propagation is by 1- or 2-jointed cuttings of the well ripened growths inserted in sand with brisk bottom heat, when they will usually root very readily. Seeds are not often produced in this genus, though occasionally well grown plants will produce seeds, which should be sown as soon as ripe, in pans of light, peaty soil, with a goodly proportion of silver sand mixed with it, and the pans placed in a warm, moist atmosphere. If given good attention the seedlings will flower the first year. Dipladenias thrive best when potted in fern or kalmia root fiber only. The potting should be attended to in early spring, just before active growth commences. Care must be taken not to injure their tuberous roots, as this will result in weakening very materially the vitality of the plants. Great care must also be exercised in watering until the plants are in active growth, when they will require an abundance of water at the roots; they are also greatly benefited by an occasional watering of clear liquid cow- or sheep-manure water. Frequent spraying of the foliage will also be necessary to keep down the attacks of insects. Dipladenias do best when grown in full sunlight, the root of an unshaded greenhouse being well suited to them. The pots should be covered with some nonconducting material, however, such as sphagnum moss, to prevent injury to the roots by the heat of the sun. As soon as the season of blossoming is past, the plants should be cut back, and allowed to rest by gradually withholding the water, keeping them during the winter almost dry in a temp. of 55°.
Edward J. Canning.
The following kinds sold in America are presumably horticultural varieties which have been insufficiently described:
D. amabilis. Lvs. short-stalked,oblong. acute: fls. rosy crimson, 4-5 in. across; corolla lobes very round and stiff. See Gn. 51. p. 227. Said to be a hybrid of D. crassinoda and D. splendens.- D. Brearleyana. Lvs. oblong, acute. dark green: fls. pink at first, changing to rich crimson, very large. Gn.5l.p. 226.- D. exmia. A recent hybrid. - D. hybrida. Lvs. large, stout, bright green: fls. flaming crimson red.- D. insignis. Stout growing; foliage strong; fls. rosy purple.
A. Fls. dark purple.
atropurpurea, DC. Glabrous, lvs. ovate, acute: racemes axillary, 2-fld.: peduncles a little longer than the lvs.; pedicels twisted, bracted; calyx lobes lanceolate-acuminate, a little shorter than the pedicel, and a third as long as the cylindrical part of the corolla; corolla tube tunnel-shaped above the middle; lobes triangular, wavy, spreading, shorter than the dilated part of the tube. Brazil. B.R.. 29:27. Gn. 44:937. I.H. 42:33. Gt. 43, p. 548.- Lvs. about 2 in. long, acute at the very base: petiole V, in. long: corolla dark purple inside and out; tube 2 in. long. None of the pictures cited above show the fleshy, spreading, scale-like stipules nearly as long as the petioles which De Candolle says are characteristic of the subgenus Micradenia. F.S. 1:33 is said to be D. atrovialacea of the subgenus Eudipladenia, in which the stipules are absent or else small and erect. The plate shows a strongly ribbed corolla-tube and lvs. cordate at the base.
AA. Fls. white: throat yellow inside.
Boliviénsis, Hook. Glabrous: stems slender: lvs. petioled, 2-3 % in. long, oblong, acuminate, acute at base, bright green and glossy above, pale beneath; stipules none: racemes axillary, 3-4-fld.: peduncles much shorter than the lvs., about as long as petioles and pedicels: bracts minute at the base of the twisted pedicels: calyx lobes ovate, acuminate, 3 lines long: corolla almost salver-shaped, tube and throat slender and cylindrical, the former % in. long, the latter twice as long and half as broad again: limb 1 1/2in. across; lobes broadly ovate, more acuminate than in D. atropurpurea. Bolivia. BM. 5783. Gn. 44:922. Gng. 7:342.
AAA. Fls. rose: throat deep rose or purple within, whitish outside.
spléndens, DC. Fig. 718. Stem glabrous: lvs. subsesslle, elliptic-acuminate. cordate at the base, wavy, pubescent, especially beneath, veins elevated, numerous: racemes axillary, longer than the lvs., 4-6-fld.: calyx lobes red-tipped, awl-shaped, as long as the cylindrical part of the corolla tube, which is half the length of the funnel-shaped portion: lobes of the limb rotund, subacute, almost as long as the tube. Brazil. Lvs. 4-8 in. long, 1 1/2-3 in. wide, pedicels 1/2-1 in. long: corolla tube 1 1/2 in. long, white outside, lobes rosy, throat deeper, almost purple. Brazil. B.M. 3976. F.S. 1:34 shows a yellow throated form. Var. profusa, Rod. (D. profusa, Hort.), has larger and brighter rosy fls., lined
with yellow inside. the outside of the tube rosy except at the base, which is yellow. I.H. 30:491. -lnt. by B. S. Williams. D. amabilis, Hort., is said to be a hybrid of D. crassinoda and D. splendens. l.H. 27-396, shows a 12-fld. raceme with exceptionally bright red fls.
AAAA. Fls. salmon-colored: throat yellow inside and out.
urophylla, Hook. Named for the long, narrow apex of the leaf. Glabrous, erect bush, not a vine : branches numerous, swollen at the joints: lvs. ovate-oblong, obtuse at the base, suddenly narrowed at the apex into a narrow point 3/4 in. long; peduncles long, drooping, flexuose: racemes axillary, 4-6-fld.: calyx segments awl-shaped: corolla dull yellow outside, deeper and brighter yellow within; tube cylindrical in lower third, then swelling into an almost bell-shaped throat; lobes of the limb salmon inclined to purple. acute. Brazil. B.M. 4414. P.M. 16:66. F.S. 5:425.
D. crassinoda. DC. Glabrous: stem much branched, with many nodes: lvs. lanceolate, acute or almost acuminate. acute at the base. shining and leathery on both sides: racemes axillary, about 6-fid.: calyx lobes lanceolate, acuminate, a little shorter than the cylindrical part of the corolla tube. 2 or 3 times shorter than the pedicel; corolla tube bell-shaped above the middle; lobes obovate-orbicular. The above is the original description by De Candolle, who adds that the lvs. are 3-3 1/2 in. long, 3/4-1 in. wide. petiole 2-3 lines long: stipules interpetiolar, with 4 short cuspidate teeth. The plant pictured in B.R. 30:64 was renamed D. Lindleyi by Lemaire chiefly for its pilose stem and stellate-lobed stipules. Later authorities refer B.R. 30:64 to D. Martiana. F.S. 22:2310 may be the same plant as B.R. 30:84, but with variable lvs. and stipules. The plant was prized for its delicate colors, being white at first, then shot with soft rose like a flame tulip, and finally a deep rose. Only one flower in a raceme was open at a time. and each lasted 8 or 9 days, throat orange inside. D. crassinoda is said to be a parent, with D. splendens, of D.amabilis. (Gn. 44. p. 141.) D. Harrisii, Hook. =Odontadenia speciosa.- D. illustris, DC. Glabrous or pubescent: lvs. oblong or rotund, obtuse or nearly acute, rounded or subcordate at the base, many nerved; stipules none; petiole short: racemes terminal, 4-8-fld.: fls. rosy, throat yellow inside, purple at the month: corolla tube cylindrical to the middle, then funnel-shaped; limb 3-3 1/2 in. across, lobes rosy, orbicular-ovate. obtuse. Brazil: F.S. 3:256. Var. glabra, Muell. Arg. B.M. 7l56.- D. Sanderi. Hems., has flesh-colored fls. with throat yellow inside, and outside at the base has smaller lvs. than D. illustris, and no circle of purple at the mouth of the fl. Gn. 51:1111.