REST-HARROW. 



also fixed oils and fat, when aided by heat. 

 The mineral acids convert it into artificial 

 tannin ; the alkalies into soap. Resin in com- 

 bination with wax, a little oil of turpentine and 

 wax, forms a good polish for furniture. Resin 

 contains oxygen 13-337, carbon 75-944, hydro- 

 gen 10-719. The chief of the other resinous 

 substances are elemi, copal, mastic, sandarac, lac, 

 labdanum, amber, &c. They are almost all solu- 

 ble in alcohol. 



REST-HARROW (Ononts,from onos, an ass, 

 and onemi to delight; some of the species are 

 said to be grateful to asses). All the plants 

 belonging to this genus are of easy cultivation, 

 and several of them are rather handsome when 

 in flower. The common rest-harrow or cam- 

 mock (O. arvensis), is a native plant, with a 

 woody, tough, and strong root, resisting the 

 harrow's prongs, whence the English name. 

 The stems are annual, though often considera- 

 bly woody, or shrubby, various in length, hairy. 

 Leaves generally simple, entire towards their 

 base. Flowers mostly solitary, large, and 

 handsome, of a brilliant rose colour. See Pl.x.Ar. 



RHIZOMA (Lat. Rhiza, a root). A term ap- 

 plied to roots which spread under ground, like 

 those of the iris. 



RHODODENDRON (From rhodo, a rose, and 

 dendron, a tree, because of the appearance of 

 the terminal bunches of flowers). The rhodo- 

 dendron is decidedly one of the finest of all 

 known genera, containing some of the most 

 handsome, elegant, and showy shrubs ; all of 

 which are admirably adapted either for orna- 

 menting the green-house or shrubbery, or for 

 planting singly on lawns. Peat soil is most 

 suitable to these plants, but they may also be 

 grown in very sandy or vegetable mould. They 

 are propagated by layers or seeds. The small- 

 wooded kinds may be also increased very freely 

 by young cuttings, planted in sand, under a 

 glass. 



The species found in the United States are, 

 the Rhododendron nudiflorum, or naked-flowered 

 rhododendron, commonly called the wild ho- 

 ney-suckle, a beautiful American shrub found 

 in the Middle States, frequent in woodlands 

 and thickets, where it blooms from April to 

 May. The flowers are of various shades, from 

 very pale to bright purple. There are appa- 

 rently several varieties of this beautiful flow- 

 ering shrub. The leaves are subject to large 

 green excrescences, produced by the puncture 

 of insects. See AZALEA. 



Rhododendron viscosum, clammy rhododendron, 

 or sweet white honeysuckle, a fragrant, pretty 

 species, with very clammy white flowers, found 

 in rocky woodlands in the Middle States, flow- 

 ering in June. The stems grow to the height 

 of 4 or 6 feet, with numerous short and crooked 

 branches. See AZALEA. 



The Rhododendron maximum, or dwarf rose 

 bay, forms a magnificent ornament of the 

 American mountain forests. It generally pre- 

 sents itself in the form of a shrub, of less than 

 10 feet in height, although it occasionally at- 

 tains an elevation of 20 to 25 feet, with a di- 

 ameter of 4 or 5 inches. 



RHUBARB (Rheum rkaponticwn, from pza, to 

 spread, and Rheum hybriJum'). A hardy peren- 

 nial plant, a native of Asia. The leaves are 

 948 



RHUBARB. 



[. very broad, and 2 feet long. Their petioles or 

 stalks are large, and these only are used. They 

 are agreeably acid and vinous, very wholesome, 

 and much admired, whether stewed alone with 

 sugar for tarts, and puddings, and pies, or com- 

 bined with other fruits. Its use with us is fast 

 increasing, and although its introduction to the 

 London market did not take place, it is said, 

 till 1815, yet now, we are told, a thousand cart- 

 loads are there annually sold. The soil best 

 suited to these plants is one that is light, rich, 

 deep, and moderately moist. A poor heavy or 

 shallow soil never produces them in perfection. 

 It may be propagated by cuttings, but the 

 mode almost universally practised in England 

 is by seed. This should be sown soon after it 

 is ripe in September or October, for if kept out 

 of the ground until the spring, it will often con- 

 tinue dormant for twelve months ; if the danger 

 of this, however, is risked, it must be inserted 

 early in February or March. The seeds are 

 best inserted in drills 3 feet apart and an inch 

 deep, the plants to remain where raised; for 

 although they will bear removing, yet it always 

 checks and somewhat lessens their growth. 

 When they make their appearance in the 

 spring, and have been thoroughly cleared of 

 weeds, they may be thinned to 6 or 8 inches 

 asunder, and the surface of the ground about 

 them loosened with the hoe. Towards the con- 

 clusion of summer, when it can be determined 

 which are the strongest plants, they must be 

 finally thinned to 3 or 4 feet, or the hybrid to 6. 

 They must be continually kept clear of weeds. 

 In autumn, when the leaves decay, they aj~e 

 removed, and the bed being gently turned over, 

 a little well-putrefied stable-dung added, and 

 some of the earth applied over the stools. In 

 the spring, the bed may be again dug, previous 

 to the plants making their appearance ; and as 

 the stalks, when blanched, are much less harsh 

 in taste, require less sugar to be rendered 

 palatable, and are greatly improved in appear- 

 ance, at this period a trench may be dug 

 between the rows, and the earth from it laid 

 about a foot thick over the stool. This cover- 

 ing must be removed when the cutting ceases, 

 and the plants allowed to grow at liberty. As 

 the earth in wet seasons is apt to induce decay, 

 the covering may be advantageously formed 

 of coal-ashes or drift-sand, which are much 

 less retentive of moisture. Those plants pro- 

 duce the seed in greatest perfection that are 

 not gathered from, but on no account must they 

 be subjected to the process of blanching. Two 

 year old plants often produce seed, but in the 

 third year always. It must be gathered as soon 

 as ripe, and great care taken that none is scat- 

 tered over the beds, for the plants then pro- 

 duced often spring up and greatly injure the 

 old plants by growing unobserved amongst 

 them. 



Varieties. 1. Buck's new early Scarlet Rhubarb. 

 A new and beautiful variety, and very early. 

 The stalks and the juice are of a beautiful red 

 colour, and quite as high-coloured as the juice 



! of red currants, and of excellent flavour. Fit 



{ for use, in our climate, in April. 



2. Tobolsk. A new and very superior va- 

 riety; the earliest of all the early, not except- 



i ing, perhaps, Buck's Early Scarlet. The stalks 



