|Standard Cyclopedia of Horticulture|
Rheum (Rha was the old Greek name for rhubarb). Polygonaceae. Rhubarb. Perennial (sometimes mono- carpic) herbs grown for the large bold foliage and often interesting inflorescence; and one for the edible leafstalks.
Leaves mostly radical, large for the size of the plant, entire or divided, on stout thick petioles: sts. mostlystrict and rising above the heavy foliage, often tall, making plants of striking habit: fls. perfect, small, greenish or whitish, pedicellate, in numerous panicled fascicles or racemes, the infl. elevated on stout mostly hollow scape-like sts., which are provided with sheathing stipules or ochreae (Fig. 3374) ; perianth 6-parted and spreading; stamens 9 or 6; ovary 3-angled and bearing 3 styles, ripening into a winged or sometimes nearly succulent achene.—Species about 25, Syria and Siberia to China, through the Himalayan region.
Aside from the common rhubarb, Rheum Rhaponticum, which is grown for the edible leaf-stalks, the species are little known in general cultivation. Few plants are more useful, however, for bold and striking foliage effects; and these effects are heightened by the towering flower-panicles. Most of the species are hardy and easy to grow, but they profit by a liberal winter mulch. Rheums are usually seen to best advantage against a heavy background of foliage or of rock (Fig. 1817, p. 1463). Even the common rhubarb is a useful ornamental subject when well placed. In order to secure large and fine foliage, the soil should be rich and moist. The species are propagated by dividing the root-masses, preferably in spring, leaving as much root as possible with each strong eye or bud.
The dried rhizomes of rhubarb are used medicinally. Several species afford the officinal product. The larger part of the dried rhubarb imported from the Orient is prob-ably made from the crown or short stem (not the flower-stem) of R. Rhaponticum is some-times grown for its medicinal roots.
R. acuminatum. Hook f. & Thom. Dwarf plant (seldom exceeding 3 ft.), like a small form of R. emodi, withacuminate lvs., but fls. considerably larger: said to be an attractive plant in cult, but to die after flowering: sts. and infl. deep red-purple. B.M. 4877. G. 36:659.—R. gunneroides, Hort., is a garden hybrid, of German origin, between R. emodi and R. palmatum. Himalayas.—R. nobile, Hook. f. & Thom. St. simple, 3—4 ft., densely clothed with imbricated downward-pointing bracts that conceal the short axillary peduncles: lvs. ovate-oblong or rounded, entire. When the fruit is ripe, the shingled bracts are torn away by the winds, leaving the long panicle exposed, and this may stand while another panicle grows from the crown and perhaps at some distance separated. Himalayas. R.H. 1876, p. 266. I.H. 22:209. G.C. II. 13:793. G.Z. 20. p. 104. A remarkable plant.—K. Ribes, Linn. 3-5 ft.: lvs. 1 ft. across, cordate to reniform. the margins crisped or undulate, the blade puckered or blistered: fls. green, drooping: frs. about 1 in. long, oolong-cordate, narrow-winged, blood-red, showy. Asia Minor to Persia. B.M. 7591. "Rivas" or "Ribes" is its Arabic name.—R. spiciforme, Royle. Dwarf: lvs. thick, orbic lar or broadly ovate: fls. white, in a dense spike rising about 2 ft. W. Himalaya. L. H. B.
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- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963