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Rhubarb (Rheon barbarum has been)

Rheon barbarum has been corrupted into our Rhubarb). Rhubarb. ORD. Polygoneae. About a score species have been referred to this genus, but the number may be reduced; they are hardy, robust, perennial herbs, with thick and slightly woody rhizomes, natives of Siberian, Himalayan, and Eastern Asia. Flowers pedicellate, fasciculate, ebracteolate, the fascicles disposed in narrow, paniculate racemes; perianth of six spreading segments. Leaves large, sinuate-toothed or palmately lobed, three to eight-nerved at base. R. Rhaponticum and its varieties, and R. undulatum, furnish the rhubarb so well-known and extensively employed. Several of the species are very handsome, both in their foliage and in their inflorescence. The rhubarb of commerce, an important medicine, valuable for its mild purgative properties, is afforded by several species of Rheum, of which the following are the principal: 1. R. palmatum, first found wild in 1872-3, by Colonel Prejavalsky, in the Tangut district of Kansu, the extreme north-western province of China; this is the real source of the Russian, or Turkey, Rhubarb. 2. R. officinale, from the Chinese frontier of Eastern Thibet. 3. R. Rhaponticum, generally called English Rhubarb, a native of Southern Siberia, known to have been cultivated, early in the seventeenth century, at Padua, whence it was brought to England, the first plant being raised about the year 1628. It is largely cultivated at Bodicott for medicinal pruposes. A selection of the best-known species is given below. Any of them are well worthy of cultivation as hardy, fine-foliaged plants, for wild gardens, margins of shrubberies, &c. They succeed in almost any soil, but do best where it is rich, and of a good depth. Propagated by seeds, and by division. For culture of the well-known garden varieties, see Rhubarb.

R. acuminatum (taper-pointed). fl. lurid-purple, bloody, or brownish-purple, 1/4in. in diameter, spreading; panicle slightly branched. l. broadly cordate, with a deep sinus, long-acuminate, opaque above, puberulous below; petioles slender, concave above. Root slender, often many feet long. h. 3ft. Sikkim, 1837. (B. M. 4877.) R. australe (Southern). fl. in a long, racemiform, dense panicle; calyx purple. l. sub-orbicular, broadly cordate, obtuse, flat, 3in. to 4in. long, nearly 3in. broad; petoles 4in. long, slender, slightly terete, angulate-sulcate. Stem 6ft. to 10ft. high, leafy. Root fusiform, branched. Nepaul. (S. B. F. G. 269.) R. Emodi (Emodus). fl. whitish, in a fastigiate, dense panicle. l. broad-ovate, obtuse, cordate, with slightly wavy margins, five to seven-nerved; petioles semi-terete. Stem tall, leafy. h. 6ft. to 10ft. Himalaya.

R. nobile (noble).* fl. green, insignificant, in short, branched panicles; bracts delicate straw-colour, shining, semi-transparent, concave, imbricating, concealing the flowers, the upper ones with pink edges. l., radical ones large, bright glossy green, with red petioles and nerves; stipules pink, fragile. h. upwards of 3ft. Roots thick, fleshy, sometimes many feet long. Sikkim. A lovely species. (G. C. n. s., iii. 91.) R. officinale (officinal).* fl. greenish, small, collected into dense spikes. l. large, somewhat orbicular-reniform, five-nerved, and cut into five short lobes at the margin; lobes unequally incised. Stem 8ft. to 10ft. high, leafy and much-branched. Thibet, 1871. A stately plant. (B. M. 6135; B. M. Pl. 213; R. H. 1874, 13.) R. palmatum (palmate-leaved). fl. in a leafy panicle. l. sub-orbicular-cordate, palmately lobed, slightly scarbrous or glabrous above, three to five-nerved; lobes ovate-oblong or lanceolate, acute, undivided, or incised-toothed or pinnatifid; petioles nearly cylindric. h. 5ft. East and North Asia, 1763. (B. M. Pl. 214.) R. Rhaponticum (Rha ponticum-i.e., pontic Rha or Rheum, the name of the drug Rhubarb in the Latin medical writers-applied to the present species by the old botanists). Common cultivated Rhubarb. fl. densely disposed in a leafy, fastigiate panicle. l. sub-orbicular, profoundly cordate, undulated, five-nerved, glabrous above, puberulous below and on the veins; upper ones ovate or acuminate; footstalks long, thick, and fleshy, channeled above, and rounded at the edges. h. 4ft. 1573. (B. M. Pl. 215.) R. undulatum (undulated). fl. densely disposed in a fastigiate panicle, which is leafy below. l. ovate-cordate, undulated, five to seven-nerved, glabrous above, puberulous beneath; uppermost ones sub-sessile, two or three times longer than broad; petioles semi-terete, loosely channelled above, with rounded margins. Stem 4ft. to 5ft. high, smooth, green. Siberia, &c., 1734. See Fig. 364.

RHEXIA (from rhexis, a rupture; applied to this genus for no obvious reason). ORD. Melastomaceae. A genus comprising about seven species of mostly hardy, pretty, erect herbs or sub-shrubs, natives of extra-tropical Eastern North America. Flowers variously coloured, solitary or cymose; calyx tube oblong, campanulate, or urceolate, the dilated limb of four triangular or subulate lobes; petals four, obovate; stamens eight. Leaves oblong, shortly petiolate, three-nerved, entire or bristly-serrulate. The species described below are all hardy herbs. They thrive best in a bed of peat, but are sometimes grown in pots of the same soil. Propagation may be readily effected by division. Some of the plants formerly placed under this genus are now included under Pleroma (which see).

R.ciliosa (hair-fringed).* fl. purple, 1in. to 1 1/2in. in diameter; cyme few-flowered, leafy. July and August. l. rarely as much as 1in. long, ovate, bristly on the upper surface, three-ribbed. Stem simple, 1ft. to 1 1/2ft. high, smooth, four-angled above. 1812. (S. B. F. G. 298.) R. mariana (Maryland). fl. purple, 1 1/2in. to 2in. wide, hairy externally; calyx mostly smooth. July to September. l. lanceolate, acute, short-petioled, bristly-serrate, three-ribbed. Stem 1ft. to 2ft. high, branched, terete or six-angled. 1759. Plant bristly. This species varies with narrower, often linear leaves, and smaller, whitish flowers. (L. B. C. 366; S. B. F. G. 41.) R. virginica (Virginian).* Deer Grass; Meadow Beauty. fl. bright purple, cymose. July and August. l. ovate and ovate-lanceolate, barely acute, sessile, bristly-serrate, three to five-ribbed, the lowest rounded. Stem 6in. to 12in. high, four-angled, nearly simple. 1759. Plant bristly. (B. M. 968; Gn. ii. 294, 69; L. B. C. 840.) RHINACANTHUS (from rhis, rhinos, the nose, and Acanthus; alluding to the curious shape of the Acanthus-like corolla). ORD. Acanthaceae. A small genus (about four species) of stove, loosely branched, sometimes sub-scandent shrubs, natives of tropical and South Africa, Madagascar, the East Indies, and the Malayan Archipelago. Flowers few, at the axils of the bracts, sub-sessile, sometimes fascicled or cymose and paniculate; calyx deeply five-cut, with narrow segments; corolla with an elongated tube and a bilabiate limb, the dorsal lip bidentate, the anterior one trifid; stamens two, affixed to the throat of the corolla. Leaves entire. The best-known species is described below. For culture, see Justicia.

R. communis (common). Ringworm Root. fl. white; upper lip linear, straight; panicle axillary or terminal, bi-or trichotomously spreading. June. l. oblong or ovate-oblong. h. 2ft. East Indies, 1790. (B. M. 325, under name of Justicia nasuta.) RHINANTHUS from rhis, rhinos, the nose, and anthos, a flower; alluding to the form of the corolla). Yellow Rattle. SYN. Alectorolophus. ORD. Scrophularineae. A genus comprising two or three very variable, erect, hardy annuals, natives of Europe, temperate and North Asia, and North America. Flowers sessile in the axils of the floral leaves, ebracteolate, upper ones spicate; calyx four-toothed; corolla yellow, violet, or blue, often spotted, with a bilabiate limb, the upper lip entire, the lower one of three spreading lobes. Leaves opposite; cauline ones crenate; floral ones often incised-toothed, with the teeth setaceo-cuspidate. The speciesare more or less parasitic on the roots of grasses, and thrive in any moist situation: they may be propagated by seeds.

R. Crista-galli (Cock's-spur). Penny-grass; Yellow Rattle, &c. fl. corolla yellow, the upper lip blue. May to July. l. distant, 1in. to 2in. long, oblong-lanceolate or linear-oblong, obtuse or acute, deeply crenate-serrate. Stem 6in. to 18in. high, erect, simple or branched. Europe (Britain). (Sy. En. B. 998, under name of R. minor.) R. major (greater). fl. orange-yellow; corolla tube longer than the glabrous calyx segments; lobes of the upper lip longer than broad; lower lip shorter than the upper. Late summer and autumn. l. opposite, sessile, deeply serrated. Stem usually copiously paniculate-branched. h. 6in. to 18in. Europe (Britain). (Sy. En. B. 999.) RHIPOGONUM (from rhips, a rod, and gonu, a knee or joint; in allusion to the jointed stalk). Sometimes spelt Ripogonum. ORD. Liliaceae. A small genus (five species) of tall, climbing, greenhouse shrubs, of which one is a native of New Zealand, and the rest are Australian. Flowers rather small, shortly pedicellate or sub-sessile, racemose or spicate; perianth segments distinct, equal, or the outer ones shorter. Leaves often mostly opposite, sometimes all alternate, three to five-nerved, with reticulated veinlets; petioles not cirrhiferous. The species are little known in cultivation. R. album requires culture similar to Myrsiphyllum.

R. album (white). fl. white, rather distant, in axillary, simple racemes, usually shorter than the leaves. June and July. fr. red when fresh, drying black, 1/3in. in diameter. l. irregularly opposite or alternate, elliptic or oblong, varying to ovate o" almost lanceolate, shortly acuminate, narrowed at base, mostly 3in. to 4in. long. Main branches often prickly. Australia 1820. RHIPSALIS (from rhips, a Willow-branch; referring to the flexibility of the branches). Including Lepismium and Pfeiffera. ORD. Cactae. A genus of greenhouse, succulent shrubs, with sub-radicant, elongated, terete, or leafy-dilated and crenate stems. Thirty species have been described, natives of tropical America, one being found in South Africa, and one in Mauritius and Ceylon. Flowers lateral, rarely terminal; calyx tube not produced above the ovary, with three to many very short, scale-like lobes; petals six to ten, spreading, oblong; stamens numerous. Berry sub-globose, smooth. Leaves scale-like. The species best known in gardens are described below. They should be grown in a compost of sandy loam, leaf mould, and brick rubbish. Propagation may be effected by cuttings, inserted in rough gravel or brick rubbish, after having been dried at the base for a few days. R. brachiata (forked). A synonym of R. Saglionis.

R. Cassytha (Cassytha).* fl. abundant on the sides of the branchlets, often crowded; calyx teeth five or six; petals five or six, greenish-white; stamens twelve to fourteen. September. fr., berry waxy-white, like that of the Mistletoe. Stems slender, terete, firm, branched, in dense whorls, the branches again branched; joints rare, except at the branching. h. 1ft. Tropics, &c., 1758. (B. M. 3080.) R. communis (common). fl. rose, white: crenae furnished with an ovate acute scale and numerous white hairs. Summer to December. Plant articulated, erect, sub-radicant, pale green, triangular; ribs much compressed, repandly crenated. Brazil, 1836. (B. M. 3763, under name of Lepismium commune.) R. crispata (curled). fl. white, minute, scarcely odorous; petals six, ovate, reflexed; stamens numerous. December. fr., berry white, globose. Plant sub-erect, articulated; branches orbicular or oblong, sub-petiolate, yellowish-green, almost membranous, deeply crenate, the margins slightly curled. h. 1ft. Native place unknown.

R. fasciculata (cluster-branched). fl. similar to those of R. Cassytha, but smaller; petals five, dirty-yellow. fr., berry white, crowned with the remains of the corolla. Plant creeping, branched; branches fascicled, green, terete, very sparsely setose; young ones spirally sub-angular; areolae slightly clustered. Brazil. (B. M. 3079.) R. funalis (cord-like). fl. white, very copious, ten lines in diameter, inodorous; petals seven or eight; stamens very numerous; February to April. Trunk 2ft. to 3ft. high, at length woody; branches long, terete, obtuse; areolae scattered, almost naked. Central America. See Fig. 365 SYN. R. grandiflora (B.M. 2740).

R. grandiflora (large-flowered). A synonym of R. funalis. R. Houlletii (Houllet's).* fl. straw-colour, copiously produced in the axils of the marginal teeth. Branches pendulous; the articulations 3in. to 6in. long, elliptic-lanceolate, coarsely toothed, and of a glabrous-green, with a faint tinge of brownish-purple along the margins. Brazil, 1874. (B. M. 6089.) R. mesembryanthemoides (mesembryanthemum-like). fl. white, 1/2in. across at the lateral joints; petals five, much-spreading. Spring. fr., berry white. Plant glomerately branched; branches 8in. to 10in. long, sub-erect, terete, bearing rooting joints; lateral joints clustered, terete, attenuated at both ends; fascicles of spines pale white, dying off blackish. Tropical America, 1817. (B. M. 3078.) R. pachyptera (thick-winged). fl. numerous upon the joints, solitary in each crenature; calyx leaflets three, brownish; petals five, pale yellowish-green. November. Plant 1ft. to 2ft. high, proliferously jointed and branched; joints 4in. to 6in. long, oblong, remarkably compressed, 1in. to 3in. broad, the margins slightly thickened, crenate-lobed, glabrous; lateral thickened nerves leading off from the distinct midrib, curving upwards to the crenatures. Brazil. (B. M. 2820, under name of Cactus alatus.) R. paradoxa (paradoxical). fl. yellow, white; crenae remote, furnished with white hairs, and propped by leafy bracts. August to November. Plant diffusely sub-erect, sub-articulated; joints elongated, slender, three or four-sided; margins acute, crenulated, purple. Brazil, 1837. (B. M. 3755, under name of Lepismium Myosurus.) R. penduliflora (pendulous-flowered). This is closely allied to R. Saglionis; it differs in its pendulous habit, fastigiate and quite terete branches, and pendulous flowers with more obtuse petals. Tropical America, 1877. R. pentaptera (five-winged). fl. white, 1/2in. across, very copious in the crenatures of the branches and on the upper part of the trunk; petals six or seven, biseriate. February and March. Plant sub-erect, 1 1/2ft. high, long-jointed, full green; main stem five or six-angled, with slender, slightly twisted, five-angled branches; areolae remote. Brazil. R. rhombea (diamond-branched). fl. greenish-white, solitary, small. Stem terete or variously compressed, and, as well as the branches, sub-erect, articulated, diffuse; joints 1in. to 3in. long, with filiform wings, ovate-or lanceolate-rhomboid, highly glabrous, and shining, incised-crenate at the margins. Brazil. (Ref. B. 152.) R. Saglionis (Saglio's). fl. greenish-yellow, rather large, terminal upon divaricate articulations, on the lower part of the stem. h. 8in. to 10in. Plant erect or nearly so; main stem cylindrical, bearing the few scattered flowering branches below, and above many horizontal branches, which are again divided, always opposite, brachiate, and with more numerous and shorter joints as they come nearer the ultimate divisions. Buenos Ayres. SYN. R. brachiata (B. M. 4039).

R. salicornoides (Glasswort-like).* fl. yellow, terminal, solitary or in pairs; corolla superior; petals numerous, thin, concave, never opening wide. Spring. Plant trailing (young specimens erect), proliferous; branches very numerous, spreading, jointed; joints club-shaped, rounded, tubercled, smooth, scarred, glaucous; older stems grey. Brazil. (B. M. 2461; G. C. n. s., v. 731.) R. sarmentacea (twiggy-stemmed). fl. white. Stem slender, creeping, rooting, slightly branched, obtuse-angled; areolae clustered, minute, prickly, slightly tomentose; prickles eight to twelve, very slender, bristly, unequal, snow-white Bonaria, 1858. (B. M. 5136.) R. Swartziana (Swartz's). fl. whitish, minute. June. fr., berry nearly black. Stem 1ft. to 2ft. high, simply branched, winged above; summit resembling the branches. Branches 6in. to 12in. long, alternate, flat, oblong or oblong-linear, remotely crenate, tapering at the stipitate, jointed base. Jamaica, 1810.