Sempervivum
(the old Latin name used by Pliny, and derived from semper vivo, to live for ever; alluding to the well-known tenacity of the species). House Leek. Including Aeonium and Greenovia. ORD. Crassulaceae. A genus comprising fifty or more species of greenhouse or hardy, thick, fleshy herbs or subshrubs, of variable habit, often stemless, and emitting young plants from the axils, sometimes caulescent and leaf; they inhabit the mountains of Central and Southern Europe, Madeira, the Canary Islands, Asia Minor, Nubia, Abyssinia, and the Western Himalayas. Flowers white, pink, greenish, yellow, or purplish, in paniculate, often dense cymes; calyx cut or parted into six or numerous segments, rarely five-cleft; petals six or numerous, free, or connate at base, and adhering to the filaments, oblong or lanceolate, acute or acuminate; stamens twice as many, or rarely the same number, as the petals, free; filaments filiform. Leaves alternate, thickly fleshy, often revolute. S. tectorum is found growing on walls and houses in Britain, but it is not indigenous. Sempervivums succeed in any sandy soil, and may be readily propagated from seeds, or by the young plants which appear round old ones at the base. All the hardy species are admirably adapted for planting on rockwork; and the greenhouse ones, S. tabulaeforme, for instance, are valuable for succulent and carpet bedding during summer.
Mr. J. G. Baker's admirable classification of the hardy species in cultivation (published in the "Gardeners' Chronicle," n. s., vol. xii.) is appended. By its help, the names of any of the hardy species here described may be readily determined. Mr. Baker says that the following eleven forms "cannot be regarded as more than varieties or sub-species belonging to one variable specific type": S. arvernense, S. atlanticum, S. Boissieri, S. Boutignyanum, S. calcaratum, S. calcareum, S. glaucum. S. Lamottei, S. Schottii, S. tectorum, and S. triste.