312 



THE DICTIONARY OF GARDENING, 



ROELLA (named in honour of William Eoell, Pro- 

 feasor of Anatomy at Amsterdam). OED. Campanulacece. 

 A genus comprising eleven species of greenhouse, rigid 

 sub-shrubs or small, diffuse herbs, confined to South 

 Africa. Flowers sessile within the imbricating leaves, 

 solitary or glomerate; calyx with an adnate, oblong or 

 cylindrical tube and a five-parted limb, the lobes often 

 toothed ; corolla campannlate or funnel-shaped, five-lobed. 

 Leaves scattered, small or narrow, often rather rigid 

 and fascicled at the axils, entire or ciliate - toothed. 

 Several of the species have been introduced, but that 

 described below is the most desirable. A compost of 

 sandy loam and peat is most suitable for its culture. 

 Propagation may be effected by seeds; or by young 

 cuttings, which will root freely in the soil above-named, 

 if a hand glass be placed over them. 

 K. ciliata (ciliated-leaved). African Harebell, fl. solitary, ter- 



minal ; corolla white at base, with a deep purple circle, above 



pale violet, girded by white, the lobes rose-coloured. September. 



I. erect, linear, acuminated, ciliated ; upper ones longer, h. 6in. 



to 12in. 1774. (B. M. 378 ; F. d. S. 517 ; L. B. C. 1156.) 



K.(EMERiIA (named in honour of John James licemer, 



1763-1819, Professor of Botany at Landshut, and author 



of several botanical works). STN. Eomeria. OBD. Papa- 



veracece. A genus comprising only two species (and 



these, perhaps, varieties of one) of very pretty, hardy, 



annual herbs. Seeds should be sown in the open 



border, in spring, where the plants are to remain. 



R. hybrida (hybrid). Violet-flowered Horned Poppy; Wind 



Rose. fl. violet-purple with a black disk ; sepals hairy. May and 



June. Capsules 2in. to Sin. long, cylindric, hispid above. I. once 



R. refracta (bent back). A synonym of R. hybrida. 



RCEMERIA (of Trattiniok). A synonym of Steri- 

 phoma (which see). 



RCEPERA. Included under Zygophyllum (which 

 see). 



ROEZLIA (named in honour of Eoezl, a well-known 



collector, who travelled in Mexico, Central America, &c.). 



OED. Melastomaceas. A monotypic genus. The species 



is an erect, stove shrub, requiring culture similar to 



MonochaBtum (which see). 



R. granadensis (New Granada).* fl. carmine-purple ; calyx red, 

 four-lobed; petals four, roundish-ovate, emarginate ; stamens 

 four ; panicles terminal, many-flowered ; peduncles glabrous or 

 nearly so Autumn. I. opposite, petiolate, ovate lanceolate, 

 hairy on both sides, entire, five to seven-nerved. Branches sub- 

 angular. A. about 3ft. New Granada. (R. G. 706.) 



R. regla (royal). A synonym of Furcrcea Bedinghausii. 



ROGATION FLOWER. See Folygala ynlgaris. 

 ROGIERA. Included under Rondeletia (which 



see). 



ROHDEA (named in honour of Mich. Eohde, phy- 

 sician and botanist, of Bremen). SYN. Titragyne. OBD. 

 LiliacecB. A monotypio genus. The species is a green- 

 house or half-hardy, perennial, with a short, thick rhizome. 

 For culture, see Reiiieckea. 

 R. japonloa (Japanese), fl., perianth white, fleshy, Jin. long and 



thick ; spike very dense, lin. to 2in. long. January to April. 



I. all radical nine to twelve in a rosette, sub-erect, sessile, ob- 



lanceolate 1ft. long, 2m. to Sin. broad, glabrous, acute, h. 2ft. 



Japan, 1783. (B. M. 898, under name of Orontium japonicum.) 

 ROHRIA. A synonym of Berkheya. 

 ROLANDRA (named in honour of Daniel Eolander, 

 a pupil of Linnaeus, who visited Surinam). OED. Com- 

 posite. A monotypic genus. The species is a green- 

 house, evergreen shrub, with inconspicuous, white flower- 

 heads and penniveined leaves, native of tropical America. 

 It is probably lost to cultivation. 



ROLLERS AND ROLLING. For keeping walks 

 firm and in good condition, an iron Holler is requisite in 

 gardens. The size must be determined by the extent 

 and width of the walks to be Boiled. New gravel 

 walks should always have a light Roller passed over them 



Rollers and Rolling continued. 



first, and a heavy one afterwards. Others, if they are 

 firm, and have been well made in the first place, should 

 bear a heavy weight always. Boilers of almost any size 

 may be obtained in iron up to several hundredweights. 

 Boiling should only be practised when walks are suffi- 

 ciently dry to keep the gravel from clinging; the proper 

 time frequently does not last long, and, when walks are 

 rough, an opportunity for Boiling them should not be lost. 

 ROMANA. A synonym of Buddleia. 

 ROMANZOFFIA (named in honour of Count Bo- 

 manzov, a Bussian nobleman, who was a patron of scien- 

 tific studies). OED. Hydrophyllacece. A genus consist- 

 ing of only two species of low, tufted, hardy perennial 

 herbs, having much the appearance of Saxifrages ; they 

 inhabit the sub -arctic regions of Eastern Asia and 

 Western America. Flowers white, unilaterally racemose ; 

 calyx segments five ; corolla broadly or tubularly cam- 

 panulate with five imbricated, spreading lobes ; stamens 

 five, affixed to the base of the corolla. Badical leaves 

 long-stalked, cauline ones very few, orbicular-reniform, 

 deeply toothed. R. sitchensis, the only species intro- 

 duced, is a suitable subject for planting on rockwork. 

 It requires much the same culture as Saxifraga (which 

 see). 

 R. sitchensis (Sitcha).* Sitka Water Leaf. /. white ; corolla 



nearly thrice the length of the calyx ; peduncles straight. April. 



1. long-stalked, somewhat rounded-reniform in shape, h. 4in. 



Sitcha, 1873. (B. M. 6109 ; B. G. 748.) 



ROMERIA. A synonym of Rcemeria (which see). 



ROMNEYA (named after the Bev. Dr. T. Bomney 

 Bobinson, an astronomer, of Armagh). OED. Papa- 

 veracece. A monotypic genus. The species is a tall, showy, 

 branched, glabrous, herbaceous perennial, allied to Platy- 

 stigma. Although a half-hardy plant, it nevertheless 

 thrives best, and produces larger and more abundant 

 flowers if allowed space in a cool greenhouse. A rich, 

 sandy loam soil is most suitable. The species may be 

 increased by means of seeds, sown in the spring. 

 R. Coulter! (Coulter's).* fl. white, showy, terminating the 



branches, corymbose or solitary ; sepals three, scarcely lin. long ; 

 petals six, biseriate, 2iin. long, broadly obovate, thickened at the 

 base ; stamens very numerous, many-seriate. Summer. I. petio- 



late, glabrous, glaucous, pinnatifld, setose-ciliated on the margins ; 

 lower segments linear-lanceolate, upper ones deltoid ; petioles 

 one-fourth the length of the leaves. A. 2ft. to 4ft. California, 

 1875. (F. M. 252 ; G. C. n. s., iii. 280 ; Gn. xi. 374 ; B. G. 1876, 152.) 

 ROMULEA (a name commemorative of Bomulus, 

 the mythical founder of Borne). STN. Trichonema. In- 

 cluding Spatalanthus. OBD. Iridece. A genus of pretty, 

 greenhouse or hardy, bulbous plants, natives of Western 

 Europe, the Mediterranean region, and South and West 

 Africa. Fifty-four species have been enumerated, but, 

 according to the authors of the " Genera Plantarum," 

 many of these are reducible to mere varieties. Mr. Baker, 

 in his review of the genus published in the " Journal of 

 the Linnean Society," xvi. 86, accords specific rank to 

 thirty-six. Flowers one to a spathe, sub-sessile or 

 shortly pedicellate ; perianth funnel-shaped, with a very 

 short, or rarely elongated, tube, and equal, erecto-patent, 

 entire lobes ; stamens affixed to the throat ; spathes long- 

 pedunculate in the axils of the floral leaves ; bracts 

 beneath the ovary at the apex of the pedicel shorter, ai d 

 sometimes broader, than the spathe. Badical leaves 

 linear, sometimes subulate, the sheaths rarely lancio- 

 late-dilated ; cauline leaves similar, but smaller. The 

 species described below are those best known to cultiva- 

 tion. They require to be planted out in a pit or frame, 

 in a compost of sandy loam and peat. Propagation may 

 be effected by offsets. 



R. bulbocodioides (Bulbocodium-like). fl. greenish-yellow; outer 

 spathe valve navicular-convolute, inner one very slender and dark- 

 striped ; scape terete, two-sheathed. June. /., radical ones 

 fistular-sheathing ; cauline ones binate, in threes, or rarely 

 solitary, alternating with the peduncles, h. 6in. Cape of Good 

 Hope, 1810. Greenhouse. (B. M. 1392, under name of Tricho- 

 nema caulc-cenn.) 



