AN ENCYCLOPAEDIA OF HORTICULTURE. 



291 



Rhizophora continued. 



to take possession of the mud, in advance of their parent 

 stems " (Dr. Win. Hamilton, in the " Pharmaceutical 

 Journal "). R. Mangle has been introduced to this country 

 but is difficult to cultivate. 



RHIZOFHOREJE. A natural order of usually quite 

 glabrous trees and shrubs, with terete branchlets swollen 

 at the nodes, almost wholly tropical, and to a great 

 extent littoral. Flowers usually hermaphrodite, axillary, 

 disposed in cymes, panicles, spikes, or racemes, rarely 

 densely clustered or solitary, small or rather large, bi- 

 bracteolate or ebracteolate ; calyx tube more or less 

 adnate to the ovary, rarely free ; limb three to fourteen- 

 lobed or entire, persistent ; petals as many as the calyx 

 lobes, usually small, concave or involute, and embracing 

 the stamens, notched, bifid, or lacerate, rarely entire, 

 convolute or inftexed in bud; stamens twice, or three or 

 four times, as many as the petals, rarely equal in 

 number; ovary usually inferior, two to five (rarely six) 

 celled. Fruit usually coriaceous, crowned with the calyx 

 limb, indehiscent or rarely septicidal, one-celled and one- 

 seeded, or with two to five one-seeded cells. Leaves 

 opposite and stipulate, rarely alternate and exstipnlate, 

 petioled, thickly coriaceous, usually quite entire, in a few 

 cases sinuate-crenulate or serrulated; stipules inter- 

 petiolar, very caducous. The wood of Rhizophora Mangle 

 is described as edible, and when fermented produces a 

 light wine. The order comprises seventeen genera, and 

 about fifty species, none of which are of horticultural 

 value. Examples : Haplopetalum, Rhizophora. 



BiHIZOS. This term, used in Greek compounds, 

 signifies a root ; e.g., Rhizophora. 



RHODAMNIA (from rhodamnus, a small branch ; 

 in reference to the size of the plants). STN. Monoxora. 

 OBD. Myrtacece. A genus of stove or greenhouse shrubs 

 or small trees. Twelve species have been enumerated ; 

 of these, three are natives of Eastern or tropical Australia, 

 and the rest of tropical Asia. Flowers often small ; calyx 

 tube ovoid or sub-globose ; limb of four persistent lobes 

 or segments ; petals four, spreading ; pedicels short, some- 

 times very short, fasciculate in the axils, or shortly and 

 loosely racemose ; bracteoles small, caducous. Leaves 

 opposite, ovate or lanceolate, three-nerved or tripli- 

 nerved, often hoary or downy beneath. The only species 

 introduced is often erroneously classed under Eugenia. 

 For culture, see Myrtus. 



B. trinervia (three-nerved), fi. white ; peduncles slender, axil- 

 lary, three together in a cluster, or on a snort, common peduncle, 

 each with one or rarely three flowers. May. I. ovate-oblong or 

 ovate-lanceolate, acuminate, glabrous and much reticulated 

 above, prominently three-nerved from the base, beneath, as well 

 as on the young shoots and inflorescence, velvety-pubescent. 

 Australia, 1823. A tall greenhouse shrub or small tree. (B. M. 3225, 

 under name of Eugenia, trinervia.) 



RHODANTHE. . Included under Helipterum 

 (which see). 



RHODIOLA. Included under Sedum (which see). 



RHODITES. A genus of Gall-flies (Cynipidce), all 

 the known species of which, viz., six European and 

 four American, make galls on Roses, but on no other 

 plants, with the exception of R. radicum, one of the 

 American forms, which is said also to gall the roots of 

 Raspberries, and of Blackberries or Brambles. 



R. ROSCB produces the well-known Bedeguar Gall on 

 various kinds of Roses; R. spinosissinuB makes galls 

 of very varied form on twigs, leaves, and fruits of 

 Rosa spinosissima and R. canina ; R. Eglanteria makes 

 smooth, round galls, like small peas, on leaves of Rosa 

 canina and R. rubiginosa ; R. centifolice makes similar 

 galls on Rosa centifolia; R. rosarum causes the growth 

 of small, round leaf-galls, each decked with a few long 

 prickles, on various kinds of Roses ; and R. Mayri forms 

 galls on leaves and branches of Rosa canina. All the 



Rhodites continued. 



above are natives of Europe. For further information 

 see Rose-galls. 



RHODO. This term, used in Greek compounds, sig- 

 nifies red ; e.g., Rhodochiton, Rhodostachys. 



RHODOCHITON (from rhodo, red, and chiton, a 

 cloak; in reference to the large, coloured calyx). OED. 

 Scrophularinece. A monotypic genus. The species is an 

 elegant, greenhouse herb, with the petioles and pe- 

 duncles usually twisted and climbing. For culture, see 

 Maurandya. 



R. volubile (twining).* JL on axillary, elongated pedicels ; calyx 

 pale reddish, ample, broadly campanulate, seini-five-fld ; corolla 

 dark blood-colour, rather large, with five erecto-patent lobes. 

 June. I. alternate, cordate, acuminate, with a few acute teeth 

 sparsely glandular-puberulous. h. 10ft. Mexico, 1833. (B. M. 

 3367; B. k 1755; S. B. F. G. ser. it 250.) 



RHODOCISTUS BERTHELOTIANUS. A sy- 

 nonym of Cistus candidissimus (which see). 



RHODOCOMA. A synonym of Restio (which 

 see). 



RHODODENDRON (an old Greek name, from 

 rhodos, a rose, and dendron, a tree ; in allusion to the 

 rose-red flowers of many of the species). Rose Bay. 

 Azalea and Rhodora are merged, by the authors of the 

 " Genera Plantarum," into this genus, but for garden 

 purposes they have been kept distinct in this work. 

 OBD. Ericaceae. A large and popular genus of highly 

 ornamental, glabrous, pubescent, tomentose, or lepidoted, 

 stove, greenhouse, or hardy shrubs, rarely trees. The 

 species, which number upwards of 100, are natives of the 

 mountains of Europe, Asia, the Malayan Archipelago, and 

 North America, often gregarious, being copiously found 

 on the Himalayan mountains. Flowers usually large, often 

 disposed in terminal, many or few-flowered, sometimes sub- 

 racemose corymbs, rarely axillary or solitary; calyx vari- 

 able, five-sepaled, five-toothed, patelliform, cnp-shaped, or 

 obsolete, coriaceous or leaf-like, persistent ; corolla vari- 

 able, often funnel-shaped or bell-shaped, rarely tubular, 

 salver-shaped, or sub-rotate; limb more or less oblique, 

 five (rarely six to ten) lobed or rarely parted, very rarely 

 sub-bilabiate, the lobes imbricated ; stamens eight to ten, 

 rarely five or twelve to eighteen, more or less unequal, 

 sometimes spreading ; filaments subulate- filiform or short 

 and thick, usually pilose or bearded at the base. Cap- 

 sules short or elongated, woody, five to twenty-celled. 

 Leaves alternate, often clustered at the tips of the branch- 

 lets, entire, coriaceous, rarely membranous, annual or 

 biennial. 



Rhododendrons may justly be classed amongst the most 

 beautiful and attractive of evergreen, flowering shrubs. 

 Their foliage is at all times attractive, and the flower- 

 trusses, which vary much in size with the species or 

 variety, are usually borne in the greatest profusion when- 

 ever the plants succeed. Amongst outdoor shrubs, none 

 are more showy when in flower than the gorgeous varie- 

 ties and hybrids raised from R. ponticum. This species 

 itself has now been so generally superseded by varieties 

 or hybrids, that it need no longer be grown extensively, 

 except for covert planting, and for the supply of stocks 

 whereon to graft the superior forms. Some of the grandest 

 indoor plants, where space can be allowed them to develop, 

 are specimens of the Himalayan species, many of which 

 have flowers highly perfumed, in addition to their other 

 good qualities. Of late years, numerous hybrids have been 

 raised, by using, for crossing and inter-crossing, several 

 of the species and hybrids which have been from time 

 to time obtained. These are all beautiful, and well 

 adapted for culture in small pots, for greenhouse deco- 

 ration. They have always been much valued, and seem 

 deservedly to be fast increasing in popularity. 



Propagation. There are several methods by one or 

 more of which the species, hybrids, and varieties of 



