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.
Procumbent or erect shrub, to 2 ft., quite glabrous: leaves rather long-petioled; leaflets oval or obovate, dark green above, 1/2-l in. long: flowers 1-3, purple; calyx reddish: pod black, 1-1 1/2 in. long. May, June. S. Austria, N. Italy. B.M. 1176. L.B.C. 9:892. G.C. III. 36:217; 50:163. Gn. 21, p. 421. J.H.III. 49:399. variety albus, Kirchn. Flowers white. G. 6:433. variety albo-carneus, Kirchn. (variety carneus, Hort.). Flowers light pink. variety atropurpureus, Dipp. Flowers dark purple. variety elongatus, Andre (variety pendulus, Dipp.), with slender, pendulous branches and purple flowers, is sometimes grafted high on Laburnum. There exists an interesting graft hybrid of this species and Laburnum vulgare, for which see Laburnum Adamii.
aa. Calyx campanulate, as long or only slightly longer than wide: branches grooved or angled.
B. Flowers axillary along the branches.
c. Leaves simple: flowers yellow: procumbent shrubs. (Coro-thamnus.)
Prostrate shrub, 4-8 in. high: branchlets 5-angled, glabrescent: leaves oblong-obovate, obtuse or acutish, pilose on both surfaces, ciliate, 1/3-3/1in- long: flowers yellow, 1-3; calyx sparingly pilose; standard broadly obovate, 1/3in- broad: pod 1/2-3/4in. long, pilose, with 3-4 seeds. May, June. S. Eu. B.M. 8230. L.B.C. 8:718.
cc. Leaves 3-foliolate (in Nos. 9 and 10 partly simple).
D. Plant a prostrate shrub: flowers yellow or yellowish white. (Trianthocytisus.)
Prostrate shrub, about 1 ft. high: branchlets grooved, pubescent: leaves long-petioled; leaflets 3, linear-oblong, acute, covered with spreading hairs, 1/4-1/3in- long: flowers golden yellow, 1-3, crowded at the end of short lateral branchlets, nearly 1/2in. long: pod very villous, 3/4in. long. April, May. S. France. Moggridge, Flora of Mentone 58. - Very handsome, but tender.
(C. Ardoinii x C. multiflorus). Prostrate shrub: leaflets 3, linear-oblong, clothed with short soft pubescence, 1/3-1/2in. long: flowers yellowish white, 1-3, along slender branches, 1/2in. long. May. Originated at Kew. Gn. 60, p. 348; 69, p. 282; 73, p. 228; 75, p. 273. G.M. 44:579; 51:355. G.W. 16, p. 610. - Like the preceding well adapted for rockeries or for forming a close covering to the ground.
dd. Plant an upright shrub: foliage scarce.
E. Style slightly curved, shorter than keel: flowers white or yellowish white. (Spartothamnus.)
(C. albus. Link, C. Iinkii, Janka. Spartium multiflorum, Ait.). Shrub, to 3 ft., with slender, erect, grooved branches pubescent at first: leaves short-petioled, 1- to 3-foliolate; leaflets obovate-oblong to linear-oblong, 1/4- 1/2in. long, sparingly appressed-pubescent: flowers axillary, 1-3, white, 1/3- 1/2in. long: pod appressed-pubescent, usually 2-seeded. May, June. Spain, N. Africa Gn. 64, p. 251; 69, p. 92; 72, p. 276. G.M. 49:579. G.W. 5, p. 111. variety incarnatus, Sweet. Flowers white, slightly blushed. L.B.C. 11:1052 (as Spartium).
(C. multiflorus x C. purgans). Shrub, to 10 ft., with slender upright or arching branches: branchlets grooved, pubescent at first: leaflets usually 1, sometimes 3, short-petioled, oblanceolate or linear-spatulate, silky pubescent, 1/3- 3/4in. long: flowers 1-2, yellowish white, very numerous along the slender branches, nearly 1/2in. long: pod appressed-pubescent, about 1 in. long, usually 2-seeded. May. Of garden origin. G.C. III. 29:41. Gn. 56, p. 37; 65, p. 438; 69, p. 318. G.M.44:581; 52:183. M.D.G. 1903:265. G.W. 3, p. 221. variety albus, Smith. Dwarfer, more pendulous: flowers white. Gn. 75, p. 192. variety luteus, Smith. Dwarf: flowers yellow. - This hybrid is one of the most floriferous of all brooms.
(Spartocytisus filipes, Webb). Shrub, with slender, angulate, thread-like branches: leaves slender-petioled, 3-foliolate, nearly glabrous; leaflets linear-lanceolate: flowers axillary, 1-2, fragrant, pure white; wings much longer than the keel. Feb. - May. Tene-riffa. - As C. palmensis, Hort., in the American trade.
ee. Style longer than keel, spirally incurved: flowers bright yellow or partly crimson, rarely pale, large. (Saro-thamnus.)
(Sarothdmnus scoparius, Wimm. Spartium scopdrium, Linn.). Scotch Broom. Shrub, to 10 ft., with erect, slender branches: leaves short-petioled, 1-3-foliolate; leaflets obovate or oblanceolate, sparingly appressed-pubescent, 1/4- 1/2in- long: flowers usually solitary, 3/4in. long; calyx and pedicels nearly glabrous: pod brownish black, glabrous, villous only at the margin. May, June. Cent, and S. Eu. G. 25:169 -The tops are used for their sedative and diuretic properties. In Germany the flowers also are used medicinally. variety Andreanus, Dipp. (Genista Andreana, Puissant).
Flowers yellow with dark crimson wings. R.H. 1886:373. Gt. 40:1342. R.B. 19:129. J.H. III. 32:462. - A beautiful and striking variety. variety albus, Loud. (variety pdllidus, Hort. variety ochroleiicus, Zabel., variety sul-phureus, Arb. Kew). With yellowish white or pale yellow flowers Gn. 61, p. 299; 65, p. 375. G.M. 44:580. variety pendulus, Arb. Kew (C. grandiflorus, Hort., not DC C. cantabricus, Hort., not Willd.). With slender pendulous branches. There is also a variety with double flowers - All the vars. are more tender than the type. The Scotch broom, C. scoparius, has become established in this country, as a naturalized plant, in waste places from Nova Scotia to Va.; and it is also reported from Vancouver Isl. It is also recommended by landscape gardeners for covering raw and broken places. Its yellow flowers and nearly bare stems make a unique combination in the American landscape. Even when it kills to the ground in winter, it throws up its stems again in the spring.
bb. Flowers in terminal racemes, sometimes umbellike, yellow: branches very leafy.
c. Foliage deciduous: branches terete: racemes very long and slender. (Phyllocytisus.)