|Standard Cyclopedia of Horticulture|
Cytisus (Greek name for a kind of clover). Leguminosae. Broom. Woody subjects, chiefly grown for their profusely produced yellow or sometimes white or purple flowers.
Mostly low shrubs, rarely small trees: Lvs. trifoliolate, sometimes unifoliolate, rather small, alternate, deciduous or persistent, sometimes few and minute and branches almost leafless: fls. 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. Afr. 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. multilforus 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. CH
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- Cytisus Adamii, Poir.(syn. Laburnum Adamii).CH
- Cytisus alpinus, Mill. (syn. Laburnum alpinum).CH
- Cytisus austriacus. Linn. Allied to C. supinus. Lfts. narrow, oblanceolate, silky pubescent on both aides: fls. yellow; calyx densely villous. S.E. Eu., Caucasus.CH
- Cytisus Beanii, Nichols. (C. Ardoinii X C. purgans). Low shrub with golden yellow fls., and narrow mostly simple lvs. G. 30:207.CH
- Cytisus biflorus, L'Her. (syn. C. ratisbonensis).CH
- Cytisus cantabricus, Willd. Allied to C. scoparius. but prostrate, with silky Lvs. and large bright yellow fls.: pod villous. May. Spain.CH
- Cytisus congestus. Ball (Teline congesta, Webb). Allied to C. linifolius. Densely villous-tomentose. small-lvd.: Lvs. short petioled: racemes short. Teneriffa.CH
- Cytisus Dallimorei, Rolfe (C. multiflorus X C. scoparius var. Andreanus). Upright shrub with pale purple fls. G.C. III. 51:198. Gn. 74, p. 291. G.M. 65:11. B.M. 8482. There are forms with sulfur-yellow and one with orange-yellow fls.CH
- Cytisus elongato-purpureus, Hort. (syn. C. versicolor).CH
- Cytisus elongatus, Wald.st. & Kit. (syn. C. ratisbonensis var. elongatus).—C, emeriflorus, Reichb. (C. glabrescens, Sartor, not Schrank). Allied to C. Ardoini: Sparingly appressed-pubescent: branchlets angled: fls. yellow: pod glabrous. N. Italy. G.W. 15, p. 557.CH
- Cytisus fragrans, Lam. Allied to C. filipes. Petioles short: Ifts. densely pubescent: fls. fragrant, white. Spring. Teneriffa. J.H. III. 50:448.CH
- Cytisus glabrescens, Sartor., not Schrank (syn. C. emeriflorus).CH
- Cytisus handsworthensis, Paul & Sons. "A white-fld. plant suitable for the rockery."CH
- Cytisus Hille- brandtii. Briquet (Genista Hillebrandtii, Christ). A suffruticose species, with long, slender hairy sts. and trifoliate hairy Lvs. Canary Isls.CH
- Cytisus incarnatus, Hort. (syn. C. versicolor).CH
- Cytisus Laburnum, Linn. (syn. Laburnum vulgare).CH
- Cytisus nubigenus, Link (syn. C. fragrans).CH
- Cytisus purgans, Willd. Shrub, to 3 ft., appressed-pubescent: branches striped: Lvs. 1-3-foliolate, oblong or linear-lanceolate: fls. axillary, yellow, fragrant: pod glabrous. May-July. Spain, S. France.CH
- Cytisus ramentaceus, Sieb. (syn. Petteria ramentacea).CH
- Cytisus ratisbon ensis, Schaeff. Allied to C. hirsutus. To 3 ft.: branches slender, appressed-pubescent: Ifts. glabrous above, silky beneath: fls. 1-2, yellow; calyx with appressed, yellowish, silky hairs. April-June. M. Eu., W. Asia. Var. elongates, Koch. More erect: fls. larger, 3-5; calyx with somewhat spreading hairs. B.R. 4:308 (as C. biflorus).CH
- Cytisus sessilifolius, Linn. Allied to C. nigricans. Quite glabrous: Lvs. nearly sessile, with roundish-obovate Ifts.: racemes short, 4-11-fld. May, June. S. Eu. B.M. 255.CH
- Cytisus Spachianus, Kuntze (Genista Spachiana, Webb). Closely related to C. canariensis. Taller: Ifts. obovate, acuminate: racemes somewhat elongated. Canary Isls. B.M. 4195.CH
- Cytisus triflorus, L'Her. Similar to C. hirsutus. Fls. long-pedicelled, yellow; calyx-tube short, not tubular. April, May. 8. Eu., N. Afr. Tender. F.C. 3:102.-C.versicolor, Dipp. (C. hirsutus X C. purpureus). Low shrub, with sparingly villous Lvs.: fla. yellowish white and pale purple. Sometimes cult. as C. incarnatus.CH
- Cytisus Weldenii, Vis. (syn. Petteria ramentacea.)CH
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963