Rhododéndrons (Rose tree), a magnificent genus, and contains some of the most superb and gigantic plants that adorn the Green-house. All the Azàleas (except A. procúmbens) both Chinese and American, have been arranged under this genus. At present the most admired is R. arbòreum, with varieties. R. arbòreum has deep scarlet flowers, with dark spots and flakes campanulated, and in large clusters; leaves lanceolate, acute, rough, and silvery beneath. R. arbòreum albúm is very rare. R. arbòreum supérbum, flowers same shape as arbòreum, colour bright scarlet; foliage one third larger, but not silvery beneath; grows freely, and generally thought the finest variety. R. arbòrea álte-Clàrance is also very superb. There are several other varieties of minor note. A Green-house without some of the scarlet varieties of that plant, is deficient of a flower whose beauty and grandeur are beyond the highest imagination. It is a native of Nepaul in India, and when found by Dr. Wallach awakened the ambition of every cultivator and connoisseur in Europe. There are several other species brought from that country lately, but none of them has yet flowered. They are highly valued from the productions of the above; the species are R. campanulàtum, R. anthopògon, and R. cinnamòmeum. This is named from the colour of the leaves, which are very peculiar and very handsome; the flowers are said to be rose-coloured. These three last cannot be purchased under an immense price; the others have been rarely seen in our collections, but another year or two will make them more plentiful. Their beauty of flower is beyond description. The pots should be well drained, and if they are large, put several pieces of sandy stones or potshreds around the side, for the fine fibres delight to twine about such, being mountainous plants.
Roéllas, pretty leafy shrubs, with blue terminale funnel-shaped flowers, lip-spreading; R. cilliàta, R. spicàta, and R. pedunculàta, are the finest of the genus. The pots must be well drained, and care taken that they are not over-watered.
Sálvia (Sage), is an extensive genus of soft-wooded, shrubby, or herbaceous plants; very few of them do well in the Green-house, and many of them are very trifling, having no other attraction than the flower, and those of the tender species, when compared with S. élegans, S. spléndens, S. cærúlea, and S. coccìnea, (which in artificial climates constitute the standard of the genus,) are not worth cultivation. These last mentioned, if kept in the Green-house, will merely keep in life, but a situation in the Hot-house would cause them to flower frequently. The best method to adopt with the summer flowering kinds, is to plant them in the garden in May; they will grow strong and flower abundantly, and in the fall they can be lifted, and preserved during winter in pots. They neither grow nor flower so well as when planted out, and even a slip planted in the ground in moist weather will root in a few days, grow, and flower in a few weeks. S. spléndens is the best to select for the purpose. S. aùrea, S. paniculàta, and S. índica, are fine species. The latter is white and blue, with large leaves; flowers monopetalous, and irregular; colour generally red or blue in spiked whorls. All will grow easily with encouragement.
Senècios. Some species of this genus are pestiferous weeds all over the world. They are found near the limits of perpetual snow, where neither tree nor shrub is able to rear its head. Yet there are three species that are neat little plants, and are worthy of a situation, viz. S. grandiflòrus, S. venústus, and S. cineráscens, with the double white and red variety of S. élegans. The two last varieties are free flowering, but if allowed to grow several years, they become unsightly. Being very easily propagated, a few cuttings of them should be put in, in September, and in two weeks they will strike root, when they may be put in pots to keep through the winter, and then planted in the garden, continuing to renew them. The other mentioned species should be frequently done the same way. Do not keep them damp during winter, or they will rot off. Keep them in an airy exposure.
Schótias, a beautiful genus of six species, which will require the warmest part of the Green-house to keep them. The foliage is handsome; leaves compound: leaflets oval-lanceolate, and in pairs from six to ten; S. speciòsa, crimson, flowers nearly papilionaceous, and in bunches, the most superb of the genus. S. alàta, S. latifòlia, once Omphalòbium Schótia, and S. tamarindifólia, are the finest; the flowers of the others are red. The pots require to be drained, and the plants protected from the hot sun.
Swainsònas, four species of free flowering, soft wooded shrubs, natives of New South Wales. S. galigifòlia, S. coronillæfòlia, and S. astragalifòlia, are red, purple, and white; leguminose flowers in spikes from the axils, are of easy culture, and deserving of a situation; the foliage is pinnate; leaflets ovate, acute.
Scòttias, three species of valuable plants; S. dentàta, with scarlet leguminose blossoms; leaves opposite, ovate, accuminate, serrate; S. angustifòlia has brown flowers; S. trapezifòrmus, leaves ovate, acute, serrulate. We do not know the colour of its flowers; the pots must be well drained, and the plants kept in the warmest part of the Green-house, and near the light.
Sparrmánnias, are strong growing Green-house shrubs. S. africàna, is a plant very common in our collections, with large three lobed cordate leaves, hairs on both sides; flowers from March to July. S. rugósa. The leaves are rugged; flowers of both are white, in a kind of corymb, supported by a long footstalk; buds drooping, flowers erect. There is a plant known in our collections, as the free-flowering Sparrmánnia, (which is Entèlia arboréscens,) and is easily distinguished from Sparrmánnia by the leaves being cordate, accuminate, and otherwise, by all its filaments being fertile, and the flowers more branching, and blooming from November to June, profusely; very easily cultivated, and desirable.
Sphærolòbiums, only two species of leafless plants, with yellow and red leguminose flowers, which proceed from the young shoots. S. vimíneum and S. médium. They flower freely, and are easily cultivated. The old wood should be frequently cut out where it is practicable. Drain the pots.