RHO 



OR, BOTANICAL DICTIONARY. 



R H U 



467 



6. Rhododendrum Ponticum ; Purple Rhododendrum. 

 Leaves lanceolate, shining, smooth on both sides ; racemes 

 terminating ; segments of the calix oval, obtuse ; corolla bell- 

 shaped, spreading. Trunk upright, shrubby, commonly the 

 height of a man, but sometimes only half so high, frequently 

 thicker than the human arm, very much branched from the 

 bottom irregularly ; the wood white, the bark ash-coloured. 

 Tournefort remarks, that the flowers of this plant were re- 

 puted to impart a noxious quality to honey. It flowers in 

 May and June. -Native of the Levant and Gibraltar; also of 

 Georgia, and in the southern subalpine tracts of Caucasus, 

 where it affects wet places in Beech and Alder coppices, on 

 rocky mountains, but not on high alps. Common in the 

 European gardens, where it blossoms beautifully in the open 

 ground in June, but by forcing in a pot, much earlier. 

 Male varieties may be obtained, and some of them will? deci- 

 duous leaves, between this plant and the Azaleas. 



7. Rhododendrum Caucasicum. Leaves ovate rusjged, 

 bent in at the edge ; umbels terminating ; bractes elongated. 

 Root creeping among Moss, thick, woody; trunk arborescent, 

 eighteen inches high, diffused and procumbent, scarred, 

 ascending at the end, and there leafy and flowering. Native 

 of the higher rocks of Caucasus, near the perpetual ice. 



8. Rhododendrum Kamtschaticum. Leaves ciliate, nerved; 

 corollas wheel-shaped; calices leafy. This is a very elegant 

 undershrub ; root woody, dry, the size of a quill, creeping 

 by prostrate runners of a brown testaceous colour. The 

 partial peduncles have one or two lanceolate leaflets and a 

 nodding flower, of a rose-colour. It was first discovered by 

 Steller ; and grows abundantly in the peninsula of Kamts- 

 chatka and Behring's Island, in muddy places on the moun- 

 tains. It begins to flower at the end of July, and ripens its 

 seeds towards the end of September. 



9. Rhododendrum Maximum ; Broad-leaved Rhododen- 

 drum. Leaves oval, shining, blunt, veined, with an acute 

 reflex marg.in; peduncles one-flowered. In its native soil it 

 grows fifteen or sixteen feet high, with a shrubby stalk, 

 sending out a few branches towards the top. Native of 

 North America, upon rocks and in barren soils, where it 

 continues flowering great part of the summer, and is a great 

 ornament to the barren rocks. 



10. Rhododendrum Catawbiense. Leaves short-oval, 

 rotundate obtuse, glabrous, discoloured ; umbels terminal ; 

 segments of the calix elongate-oblong ; corolla campanulate, 

 scarlet. Grows on the high mountains of Virginia and Caro- 

 lina, particularly on the head-waters of the Catawba river, 

 and flowers in May and June. 



Rhodora; a genus of the class Decandria, order Monogy- 

 nia. GENERIC CHARACTER. Calix: perianth one-leafed, 

 five-toothed, permanent. Corolla: petals three, unequal; 

 the two lowermost lanceolate equal ; the upper one wedge- 

 shaped, ascending, three-lobed, the middle lobe rather longest. 

 Stamina: filamenta ten, filiform, declined, the length of the 

 corolla; antheree roundisn, twin. Pistil: germen ovate, 

 furrowed ; style filiform, declined, a little longer than the 

 stamina; stigma five-cleft, thickish. Pericarp: capsule 

 ovate, five-celled. Seeds: very many, minute. ESSENTIAL 

 CHARACTER. Calix: five-toothed. Petals : three, unequal. 



Stamina : declined. Capsule : five-celled. The only 



species yet known is, 



1. Rhodora Canadensis ; Canadian Rose-blossom. Stem 

 upright, somewhat branched, round, ash-coloured, two feet 

 high; leaves deciduous, alternate, stalked, veiny, hairy; 

 flowers appearing before the leaves, in umbels on short pe- 

 dicels, purple, the upper lip with darker spots. It is chiefly 

 distinguished from the Rhododendrum by its three-petalled 

 VOL. ii. 105. 



corolla; and appears to be generally distinct from them, 

 especially in the herb. Native of Newfoundland. It is 

 difficult to raise it from seeds ; but may be propagated by 

 slips or cuttings, and thrives best in a good sandy loam. 



Rhubarb. See Rheum. 



Rhubarb, Monk's. See Rumex Alpinus. 



Rhus; a genus of the class Pentandria, order Trigynia. 

 GENERIC CHARACTER. Calix : perianth five-parted, 

 inferior, erect, permanent. Corolla : petals five, ovate, from 

 upright spreading. Stamina: filamenta five, very short; 

 antherae small, shorter than the corolla. Pistil: germen 

 superior, roundish, the size of the corolla ; styles scarcely 

 any ; stigmas three, cordate, small. Pericarp : berry round- 

 ish, one-celled. Seeds: one, roundish, bony. ESSENTIAL 

 CHARACTER. Calix: five-parted. Petals: five. Berry: 

 one-seeded. Observe. This genus consists of trees and 

 shrubs: the flowers are in panicles or close racemes, in some 

 hermaphrodite, in others male and female on separate plants; 

 in the two last polygamous, having males mixed with the 

 hermaphrodites. From this distinction of the sexes Mr. 

 Miller has divided the genus into, Rhus having hermaph- 

 rodite flowers, and Toxicodendron having dioecous flowers. 



The species are, 



* With pinnate Leaves. 



\ . Rhus Coriaria ; Elm-leaved Sumach. Leaves pinnate ; 

 leaflets elliptic, bluntly toothed, villose underneath. Stem 

 woody, strong, dividing into many irregular branches, and 

 rises to the height of eight or ten feet; the bark is hairy, and 

 of an herbaceous brown colour whilst young. The branches 

 are used instead of Oak-bark for tanning leather ; and it is 

 said that all Turkey leather is tanned with this shrub. The 

 leaves and seeds are used in medicine, and are esteemed very 

 restringent and styptic. The Tripoli merchants sell the 

 seeds at Aleppo, where they are in common use at meals to 

 provoke an appetite. Native of the south of France, Spain, 

 Italy, the Levant, and Africa. Frequent in our gardens and 

 shrubberies, flowering in July, and retaining its dense, branch- 

 ed, ample, upright clusters of deep-red, rough, coriaceous 

 berries, till winter, after the leaves have fallen. The taste of 

 the fruit is very acid and astringent. Propagation and Cul- 

 ture. The first, second, fourth, fifth, and ninth species, are 

 hardy plants, and will thrive in the open air in England; but 

 the first and fifth not being quite so hardy as the others, must 

 have a better situation, otherwise their branches will be injured 

 by severe frost in the winter. They are easily propagated by 

 seeds- obtained from the countries where they grow; if these 

 be sown in autumn, the plants will come up the following 

 spring ; but if sown in the spring, they seldom come up till 

 the next spring : they may be either sown in pots, or the full 

 ground. If they are sown in pots in autumn, the pots ought 

 to be placed under a common frame in winter, where the 

 seeds may be protected from hard frost, and if in the spring 

 the pots are plunged into a very moderate hot-bed, the plants 

 will soon rise, and thereby have more time to get strength 

 before winter. When the plants come up, they must have a 

 large share of air, and should be gradually hardened to bear 

 the open air, into which they must be removed as soon as 

 the weather is favourable, placing them where they may have 

 the morning sun, and keeping them clean from weeds ; in 

 dry weather, a good supply of water will promote their growth, 

 which should be stinted towards autumn by keeping them 

 dry, that the extremity of their shoots may harden ; for if 

 they are replete with moisture, the early frosts in autumn 

 will pinch them, and sometimes cause the shoots to decay 

 almost to the bottom, where the plants are fully exposed. 

 If the pots are put under a common frame again in autumn, 

 6C 



