Seeds are largely employed, but they are small and light and must be carefully handled. They are sown in spring in pans or boxes in a soil of sandy peat, care being taken to cover them very lightly and not to dislodge them when applying water. They are handled in cold-frames or in a cool house, and the young plants must be shaded. The plants are commonly allowed to remain a year in the boxes. Low growing plants are often layered. Cuttings of growing wood, cut to a heel, are sometimes employed, being made in summer and handled in a frame, but the percentage of rooted plants will often be small. Rhododendrons are extensively grafted, the veneer method being most used. The operation is performed upon potted plants in late summer or early fall, or sometimes in a cool house in early spring. Most of the leaves are allowed to remain upon the cion. The plants are then placed in densely shaded cool frames, and are nearly covered with sphagnum. Various stocks are employed, but for severe climates the hardy species like _R. Catawbiense_ and _R. maximum_ are probably best. _R. Ponticum_ is extensively used in Europe, but it is not hardy enough for the north. =Rhodotypos.= See Kerria. =Rhubarb.= See Rheum. =Rhus= (Sumach). _Anacardiaceæ._ Seeds, layers, suckers, root-cuttings, and cuttings of green or ripe wood. Suckers are oftenest used. =Rhynchosia.= _Leguminosæ._ Propagated by seeds and division. =Rhynchospermum.= See Trachelospermum. =Ribes= (Currant, Gooseberry). _Saxifrageæ._ Seeds, which should be sown as soon as ripe, or else stratified for new varieties. Commonly from ripe cuttings. See Currant and Gooseberry. =Richardia= (Calla) _Aroideæ._ Offsets, which should be removed and potted off when the plants are at rest. =Ricinus= (Castor Bean). _Euphorbiaceæ._ Seeds, which in the north are started in-doors. =Rivina=, Piercea (Hoop Withy). _Phytolaccaceæ._ Readily propagated by seeds; also by cuttings, inserted during spring in heat. =Robinia= (Locust, Rose Acacia). _Leguminosæ._ Seeds, sown in fall or spring, and which usually germinate better if soaked in hot water previous to sowing. Also grown from layers and root-cuttings. Named varieties are grafted or budded, the common locust stock (_R. Pseudacacia_) being preferred, even for the rose acacia (_R. hispida_). =Rocambole= (_Allium Scorodoprasum_). _Liliaceæ._ "Cloves," or divisions of the bulb. =Rocket=, ornamental sorts. See Hesperis. =Rocket Salad= (_Eruca sativa_). _Cruciferæ._ Seeds, sown where the plants are to grow. =Rock-Rose.= See Cistus. =Romneya.= _Papaveraceæ._ Propagated by seeds in spring. =Romulea.= _Irideæ._ Offsets. =Rondeletia=, Willdenovia, Rogiera. _Rubiaceæ._ Seeds. Cuttings of half-ripened wood, inserted in sand under glass, in heat.