Rhodochiton—­This evergreen climber makes a fine plant for trellis-work.  It is more suitable for the greenhouse, though it may be grown in the open in summer.  A light, rich, well-drained soil is its delight, and it may be propagated by seed or by cuttings under glass.  In the greenhouse it should not be placed near the pipes.  July is its time for flowering.  Height, 10 ft.

Rhododendrons.—­Plant in October in peat, or in a compost of sandy, turfy loam, with a good proportion of decayed leaves and charred refuse.  The best position for them is a sheltered one where they can get a moderate amount of sunshine to develop the flower-buds.  They like plenty of moisture, but the ground must be well drained.  If it is desired to shift their position spring is the best time, the next best being October.  They are propagated by layers or seeds, and the small wooded kinds by slips torn off close to the stems, planted in sand, and placed under glass in heat.  The seed should be sown early in spring in pans of peat soil, and covered very lightly.  Place the pans in a frame, and when the soil becomes dry stand the pans in water nearly up to the rims until the surface is moist.  Pot off when strong enough to handle, and keep close in the frame till fresh roots are produced, then harden off.  Rhododendrons may, when desired, be transplanted in spring, even after the flower-buds are well advanced, if care be taken not to break the ball of earth round their roots.  They bloom at the end of May.  Height, 4 ft.

Rhubarb.—­Seed may be sown thinly during April in drills 1 ft. apart.  Thin out the plants 12 in. from each other, and let them grow on till the following April, then plant them out 4 ft. apart in deeply trenched ground into which a good quantity of well-rotted manure has been worked.  Large roots may be divided in autumn or early spring; every portion of the root that has a crown will make a fresh plant.  When the last of the crop has been pulled, fork in a dressing of old manure.  It may be forced out of doors by covering the ground thickly with stable manure, and placing large flower-pots over the plants to bleach them; but if forced in a frame the light need not be excluded.  None but the earliest kinds should be selected for forcing.

Rhubarb, Chilian.—­See “Gunnera.”

Rhus (Sumach).—­Lovely shrubs, growing in any ordinary soil.  The young shoots of R. Cotinus are clothed with round leaves which change to bright crimson and orange, surmounted with fluffy pink seed-vessels, while R. Glabra Laciniata resembles a tree fern.  They may be propagated either by layers or cuttings.  Height, 8 ft. to 10 ft.

Rhynchospermum (Trachelospermum) Jasminoides.—­A pretty, evergreen, woody climber for the conservatory, which succeeds best in a compost of light loam and peat; is of easy culture, and readily increased by cuttings.  It is a fine plant for rafters or trellis, and produces in July deliciously fragrant white flowers at the ends of the branches.  Height, 10 ft.