This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
(Greek, chance and tree: of no significance). Includes Siphonantha and Volkameria. Verbendceae. Greenhouse climbers and hardy shrubs and other ornamental plants, grown for the showy white, violet or red flowers.
Shrubs or trees, often scan-dent: leaves opposite or verticil-late, mostly entire or not compound: flowers in mostly terminal cymes or panicles; calyx campanulate or rarely tubular, shal-lowly 5-toothed or 5-lobed; coroll a-tube usually slender and cylindrical, the limb 5-parted and spreading, the lobes somewhat unequal; stamens 4, affixed on the corolla-tube, long-exserted and curved; style exserted, 2-cleft at the end; ovary 4-loculed: fruit a drupe inclosed in the calyx. - About 100 species, in the tropics, mostly of the eastern hemisphere. Clerodendrons are divided into two garden sections, -those with a shrubby habit, and the twining kinds. The culture is about the same for both kinds. They may be grown from seeds or from cuttings of the half-ripened wood. In either case, use 2-inch pots filled with a mixture of equal parts of leaf-mold or peat and good sharp sand. Place a cutting or a seed in each pot, and press moderately firm. Leave the pots in a tight case with a temperature of 70°, and keep the soil at all times fairly moist. When the pots are filled with roots, shift into a 4-inch pot, using a compost consisting of fibrous loam two parts, leaf-mold and sand one part each, and a fifth part of well-rotted manure.
Pot rather firm, as this insures a stronger growth, and during the growing season keep in a night temperature of 65°. - Clerodendrons may be flowered in any size pot desired, and some of the species, notably C. Balfourii (or properly C. Thomsome), can be had in flower from Easter until late September. This species is probably the best and most useful, either for decorative work or exhibition purposes; when it is grown in large pots, a good rough material may be used for potting. A good stiff fibrous loam with about one-third part of decayed manure is best. When the season's growth is completed, gradually withhold water for two months and lower the night temperature from 65° to 55°. Many of the leaves under the above treatment will drop and the wood will become firm. If plants are wanted in flower about Easter, give them a thorough soaking with water about January 1, and raise the temperature again to 65 by night, letting it rise during the day to 75 to 80 . Syringe the plants two or three times a day, which will encourage the young growths to start all over the ripened wood. When this takes place, the plant will either have to be repotted or fed liberally with liquid manure and fertilizers, repotting usually resulting in larger panicles of flowers.
If feeding is resorted to, a handful of green cow-manure to a watering-pot containing two and a half or three gallons of water is sufficient; and if any of the popular fertilizers are used for a change, a small handful to the same amount of water will answer. Water twice in between with clean water. Plants for a succession may be started when the first are beginning to show the crimson at the end of the flower, and so on until the end of July or first of August. -Clerodendrons are not subject to insect pests if kept thoroughly syringed during their growing season. If this is neglected, the shrubby kinds may become affected with brown-scale or mealy-bug, which should be immediately treated with the usual hydrocyanic gas fumigation. (George F. Stewart.)
Fig. 995. Clerodendron Thomsonae. (X 1/2)
A. Plant of twining habit.
(C. Bal-fouri, Hort.). Fig. 995. Tall, twining, glabrous evergreen shrub: leaves opposite, oblong-ovate and acuminate, strongly several-nerved, entire, pet-ioled: flowers in axillary, and terminal forking lax cymes; calyx strongly 5-angled, narrowed at the apex, white; corolla-limb light crimson and spreading; corolla-tube 1 in. long; stamens 3/4in. long. W. Africa B.M.5313. R.H. 1867:310; 1902:504. G.M. 46:173. G.W. 4, p. 439; 8, p. 173; 13, p. 340. F.E. 28:261. - A warmhouse plant of great merit, and the most popular of the tender species. Blooms profusely on the young wood. variety delectum, Hort. (C. delectum and C. delicatum, Hort.). flower-clusters very large; calyx pure white or green-tinged; corolla large, rose-magenta.
(Siphonanthus splendens, Hiern). A most excellent stove climber: stems slender, woody, glabrous, slightly angled: leaves opposite, variable, oblong-cordate, or elliptic, 4-6 in. long, dark green; petiole rather short: flowers in dense many-flowered cymes on leafy growths from the ripened wood of the previous year, bright scarlet passing into bright yellow, an inch or more in diam.; stamens 1 in. long. tropical Africa B R 28:7. R.H. 1902:504. H.U. 5, p. 325.
A garden hybrid between C. splendens and C. Thomsonse, intermediate in habit and foliage: the flowers are produced in profusion, are dull red, and are continuously borne throughout the summer months; old calices more or less persistent, and ornamental pale red after flowers are past. - As figured in R. H. 1873, 471 and Gn. 1877, 404, this recedes very little from typical C. splendens, according to Baker, but the C. speciosum hybridum of I. H. 1869, t593 is intermediate between C. splendens and C. Thomsonae.
aa. Plant of erect or self-supporting habit.
B. Corolla-tube not much if any longer than the large calyx: flowers white or light blush.