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 name for a kind of clover). Legu-minbsae. Broom. Woody subjects, chiefly grown for their profusely produced yellow or sometimes white or purple flowers.
Mostly low shrubs, rarely small trees: leaves trifoliolate, sometimes unifoliolate, rather small, alternate, deciduous or persistent, sometimes few and minute and branches almost leafless: flowers papilionaceous, axillary or in terminal heads or racemes, yellow, white or purple; stamens 10, connate; style curved: pod flat, dehiscent, with few or many seeds; seeds with a callose appendage at the base. - About 50 species in S. and Cent. Eu., Canary Isls., N. Africa and W. Asia. For a monograph of the genus see Briquet, Etude sur les Cytises des Alpes Maritimes (1894).
The brooms are ornamental free-flowering shrubs, blooming most in early spring and summer. Nearly hardy North are C. hirsutus, C. supinus, C. scoparius, C. nigricans, C. leucanthus, while the evergreen species C. canariensis, C. monspessulanus, C. filipes are hardy only South. Most of the species are well adapted for borders of shrubberies, and thrive in almost any well-drained soil and in sunny position; they naturalize themselves often very quickly in dry, gravelly soil, where few other plants will grow; C. scoparius especially does so. The cytisus ought to be transplanted carefully and when young, as they do not bear transplanting well as older plants. Some dwarf species, like C. Ardoinii, C. kewensis, C. emeriflorus, C. purpureus and C. leucanthus are very handsome for rockeries. The evergreen C. canariensis and C. racemosus are much grown in the North as greenhouse shrubs, blooming profusely in early spring; also the white C. multiflorus and C. filipes make handsome pot-plants, and may be had in bloom in February with gentle forcing. For pot-plants, a light sandy loam with peat added forms a suitable compost. After flowering the plants should be cut back and repotted as soon as they start into new growth.
After repotting, they are kept close and often syringed until they are established; then they ought to have plenty of air and only slight shade. When the new growth has been finished they may be put in the open air until frost is threatening. During the winter they should be kept in a cool greenhouse with plenty of light and carefully and moderately watered. From January they may be transferred gradually in a warmer house for forcing. Cuttings started in early spring, transplanted several times and then gradually hardened off, can be grown into flowering specimens for the following spring. Propagated by seeds sown in spring and by greenwood cuttings under glass; they are also sometimes increased by layers or by grafting. As stock C. nigricans is much used, or Laburnum vulgare for small standard trees; for plants grown in the greenhouse or South, C. canariensis is a good stock.
Of cytisus, the young growths root readily in December and January in the ordinary way. They should be shifted on as they grow. Good-sized plants can be produced if shifting and pinching is not neglected. By the following winter, the winter-propagated plants should be in 5-inch pots, in which size they are most useful. Keep very cool during winter, and withhold any forcing. They flower in March, or, if kept at a night temperature of 45°, as late as April. Syringe at all times to prevent red spider. To produce good-sized plants in one year, it is best to keep them plunged on a bench under the glass the entire summer, with little shade. Older plants can be plunged out-of-doors during July, August and September. (William Scott.) a. Calyx tubular, much longer than wide: Ivs. always 3-foliolate: branches terete. (Tubocytisus.)
B. Flowers in terminal heads with bracts at the base, yellow to white.
(C. capitalus, Scop.). Shrub to 3 ft., with erect, or sometimes decumbent, villous branches: leaflets obovate or oblong-obovate, sparingly appressed pubescent above, villous pubescent beneath,
3/4-1 in. long: flowers yellow, brownish when fading, nearly 1 in. long; standard pubescent outside or nearly glabrous: pod villous, 1-1 1/2 in. long. July, Aug. Cent. and S. Eu. L.B.C. 5:497. J.H.III. 31:161 (as Genista).
(C. albus, Hacq.). Upright shrub, to 3 ft., with villous branches: leaflets 3, oblong-obovate, obtuse or acutish, appressed pubescent, sometimes glabrous above, ciliate, 1/3-3/4in. long: flowers 3-6, yellowish white; calyx appressed-villous; standard pubescent outside: pod about 1 in. long, appressed pubescent. June, July. S. E. Eu. variety pallidus, schrad. (C. pallidus, Kerner). Flowers pale yellow. variety schipkaensis, Dipp. Low shrub, about 1 ft. high: flowers white. Bulgaria. - The oldest name for this species is C. albus, but as the same combination has been used by many writers for C. multiflorus, the name C. leucanthus is here used to avoid possible confusion.
bb. Flowers axillary, distributed along the branches. c. Color of flowers yellow.
(C. elongatus, Hort., not Waldst. & Kit. C. polytrichus, Bieb. C. ruthenicus, Hort., not Fisch.). Shrub, to 3 ft., with erect or procumbent, villous, terete branches: leaflets obovate or obovate-ob-long, villous pubescent beneath, 1/2-3/4in. long: flowers
2-3, short-petioled; calyx villous pubescent; standard glabrous on back: pod 1 in. long, villous. May, June. Cent. and S. Eu. Orient. B.M. 6819 (leaflets erroneously shown as serrate). L.B.C. 6:520 (as C. falcatus). B.R. 14:1191 (as C. multiflorus).
cc. Color of flowers white or purple.
Shrub, to 12 ft., with long and slender pubescent branches: leaflets oblanceolate, silky pubescent beneath, green and sparsely pubescent above, 1-1 3/4 in. long: flowers white, 3-8; pedicels rather long, tomentose; calyx tomentose; standard pubescent outside: pod densely tomentose-villous, l 1/2-2 in. long. May, June. Canary Isls. B.R. 2:121. L.B.C. 8:761. G. 32:291. - Recommended as a fodder plant for Calif.