AN ENCYCLOPEDIA 
OF HORTICULTURE, 309 
RIOCREUXIA (named after A. Riocreux, a cele- 
brated botanical artist). Orp. Asclepiadew. A small 
genus (four ? species) of slender, pubescent or glabrous, 
greenhouse, twining sub-shrubs, confined to South Africa. 
Calyx of five narrow segments; corolla with an elongated 
tube and linear lobes; corona sub-duplex, the exterior 
of five to ten scales, the interior of five smaller ones; 
cymes loose, umbelliform or dichotomous; peduncles 
simple or branched; pedicels filiform. Leaves opposite, 
cordate, membranous. R. torulosa, the only species in- 
troduced, thrives in sandy loam. Plenty of pot room 
and ample drainage must be afforded. Propagation may 
be effected by cuttings, taken preferably in spring, and 
inserted in sand, under a hand glass, with slight bottom 
heat. 
R. torulosa (somewhat twisted). f. pale yellow, flask-shaped, 
greenish at their ventricose base; umbels pedunculate, lateral or 
terminal, loose-flowered. Summer. 4. deeply cordate - ovate. 
Roots tuberous. 1862. (Ref. B. 157.) 
RIPIDIUM. A synonym of Erianthus. 
RIPOGONUM. See Rhipogonum. 
RITCHIEA (named in honour of Joseph Ritchie, a 
Yorkshireman, who was killed, in 1819, when exploring 
Central Africa). 
only two or three species of erect or sarmentose, climb- 
ing, stove shrubs, natives of tropical Africa. Flowers 
greenish, large, sweet-smelling, corymbose, long-pedicel- 
late; sepals four, ample, valvate; petals four or many, 
long-clawed, undulated, oblong, the blade imbricated; 
torus hemispherical, fleshy. Leaves simple, or three to 
five-foliolate; stipules obsolete. Only one species calls 
for mention here; it requires treatment similar to that 
recommended for Euadenia (which see). 
R. fragrans (fragrant). M. 4in. across ; sepals ovate-oblong, deep 
green; petals about fourteen, pale straw-colour, strap-shaped, 
acuminate, crumpled above the middle; stamens very numerous, 
spreading. June. J. alternate ; leaflets three to five, as long as, 
or longer than, the petioles, oblong or obovate-lanceolate, shortly 
petiolulate; petioles slender, 3in. to 5in. long. A. ft. 1859. 
An erect shrub. Syn. R. polypetala (B. M. 5344). 
R. polypetala (many-petaled). A synonym of R. fragrans. 
RIVEA (dedicated by Choisy to Auguste de la Rive, 
a physiologist of Geneva). ORD. Convolvulacee. A genus 
comprising only a couple of species of stove climbers 
or twiners, natives of the East Indies. Flowers large, 
_on axillary, one to three-flowered peduncles; sepals ovate 
or oblong, obtuse; corolla salver-shaped, with a long, 
cylindrical tube, and an angulately sub-lobed limb; sta- 
mens included; filamen!s short; bracts narrow. Leaves 
broad beneath, and, as well as the inflorescence, often 
woolly or silky. The species described below require 
culture similar to Ipomoea (which see). 
R. h riformis (salver-shaped). Midnapore Creeper. 
jl. pure white, large, expanding at sunset, and perfuming the air 
for a considerable distance with a fragrance resembling that of 
the finest cloves; corolla very wide; peduncles shorter than 
the petioles. July. J. cordate-roundish or altogether roundish, 
sometimes villous beneath. Western India, &c., 1799. Don 
says this species is the prince of convolvulaceous plants. 
R. ornata (adorned). fl., corolla white, silky without ; peduncles 
mostly three-flowered.. June. J. orbicularly cordate or reniform, 
large, clothed with cinereous tomentum beneath. Stem white ; 
branches silky. 1824. 
RIVINA (named in honour of A. Q. Rivinus, a native 
of Saxony, 1652-1722, for some time Professor of Botany 
and Medicine at Leipsic). Hoop Withy. Syn. Piercea. 
ORD. Phytolaccacee. A genus comprising, according 
to Bentham and Hooker, one or two species of stove, 
erect, dichotomously - branched herbs, shrubby at base, 
natives of tropical and sub-tropical America. Flowers 
hermaphrodite, racemose; perianth corolla-like, four- 
parted; segments obovate-oblong, obtuse, concave, 
coloured, unchanged and erect or spreading during fruc- 
tescence; stamens four. Fruit red, pisiform. Leaves 
alternate, slender - stalked, ovate, ovate-lanceolate, or 
cordate-ovate, acute, obtuse, or long-acuminate, obscurely 
ORD. Capparidee. A genus comprising ` 
i 
Rivina—continued. = 
crenate, membranous. Rivinas may readily be propagated 
by seeds or cuttings, which, after being inserted during 
spring, should be placed in heat. The plants grow freely 
afterwards in any rich, loamy soil. When covered with 
berries in winter time, they are exceedingly attractive. 
R. humilis (low).* Bloodberry; Rouge Plant. fl, whitish-rose, 
scarcely one line long, sub-reflexed; racemes longer than the 
leaves. January to October. fr., berries bright scarlet, disposed 
in racemes. l. (including the petiole) lin. to 2in. long, ovate, 
acuminate, sub-entire, rather thick, slightly tomentose or densely 
pubescent. Stem shrubby; branches, petioles, and racemes 
nen — h. lft. to 2ft. Carib Islands, &c., 1699. 
R. leevis (smooth).* Ji. whitish-rose, small ; racemes lin, to 2in. 
long. February to September. fr., berries red. 7. sin, to 4in. 
long, sub-cordate-ovate, acuminate, slightly crenulated, slender, 
scarcely undulated, highly glabrous. Stem shrubby; branches 
glabrous. h. 7ft. to 8ft. West Indies, 1733. (B. M. 2333.) 
1, pubescens (downy). A form with white flowers and pu- 
bescent leaves and branches. 1699. 
RIZOA. A synonym of Gardoquia (which see). 
ROADS. Road-making, under a proper system, is 
rather an expensive undertaking, particularly when the 
requisite material is difficult to procure. It is, however, 
of great importance that an approach Road or iage | 
drive, leading to a mansion, should be properly lined 
out, and formed, and be afterwards kept clean and in 
good repair. The bed should be well drained, and the 
bottom filled, to a depth of about 1ft., with hard, porous 
material, such as rough stones; on this should be placed 
about 3in. of rather finer material, such as broken 
granite or ballast, and a similar depth of finer gravel 
still put over the surface. In the formation of Roads, 
the proper levels must first be ascertained, and the full 
depth taken out altogether, should the ground be of an un- 
suitable description, The several depths of the different 
sorts of material may be best indicated by pegs driven 
in some 10ft. apart, so that their tops may be used as 
a guide for working. , 
ROAN OR ROWAN-TREE. A common name for 
Pyrus Aucuparia. 
ROAST-BEEF PLANT. A common name for 
Tris fetidissima. © 
ROBERGIA (of Schreber). A synonym of Rourea 
(which see). i 
ROBERGIA FRUTESCENS. A synonym of 
Connarus pubescens (which see). i 
ROBERTSIA. A synonym of Sideroxylon (which 
see). a 
à a 
ROBERTSONIA. Included undeyy Saxifraga 
(which see). 
ROBINIA (named in honour of John Robin, herbalist 
to Henri IV. of France, and his son, Vespasian Robin, 
- who first cultivated the Locust-tree in Europe). „ Locust- 
tree. ORD. Leguminose. A genus comprising five or 
six species of mostly hardy, sub-glabrous, clammy, or 
bristly trees or shrubs, natives of North America and 
Mexico. Flowers white or rose-purple, in axillary ra- 
cemes; calyx teeth short and broad, the two upper ones 
sub-connate; standard ample, reflexed, naked within; 
wings falcate-oblong, free; keel incuryed, obtuse; bracts 
membranous, very caducous. Leaves impari- pinnate; 
leaflets entire, reticulate-penniveined ; stipules bristly or 
spiny. The species described below are all hardy and 
deciduous, and are very handsome subjects for the orna- 
mentation of the shrubbery. Any common soil will suit 
them, provided it-be not too wet. Propagation may be 
best effected by layering; the rarer kinds, however, are 
usually increased by grafting on the commoner sorts, 
especially R, Pseudacacia, i 
R. dubia (dubita). f. pale rose-coloured, sweet 
rose ted ; 
racemes loose and ulous, June to August. 
brown, 
