Sempervivum Sempervivum, L.

22. S. tectorum L. View in CoL , Sp. Pl. 464 (1753)

(inch 5. arvernense Lecoq & Lamotte ,5. glaucum Ten. ).

Stolons up to 4 cm, stout; rosettes usually large (3-8 cm in diameter), open. Leaves 20-40 x 10- 15 mm, oblong-lanceolate to obovate, with a stout, pungent mucro, glabrous or with a very few scattered hairs on the surface, dark or somewhat glaucous green, variably tinged with red; cilia conspicuous, white, tending to coalesce in groups. Flowering stem 20-50 cm, stout, hairy; lower cauline leaves glabrous apart from cilia, the upper ones pubescent. Inflorescence large, with from 40 to over 100 usually 13-merous flowers. Sepals acute; petals 9-10 x 2 mm, ciliate and pubescent beneath, dull pink or purple; filaments purple, glabrous or slightly pubescent at base. 2« = 36, 72. • Mountains of W., C. & S. Europe, from C. Pyrenees to S.E. Alps. Au Ga Ge He Hs It Ju [Rm Rs (W)].

Extremely variable, and divided variously by different authors into species, subspecies and varieties. Much of the variation is purely phenotypic; of the genetically determined variation a large part, both in wild and cultivated plants, may be presumed to arise from hybridization. Further analysis by modern methods is required before any comprehensible and consistent subdivision of the species is possible.

A cultivar to which the Linnean type is referable, distinguished by its large size and frequent partial sterility, has been extensively cultivated in most of Europe, especially on the roofs of cottages, and is locally naturalized.

S. italicum Ricci , Ann. Bot. (Roma) 27: 7 (1961), recently described from C. Italy (Monti Lepini ), is rather like 22, but has leaves densely pubescent on both surfaces. It requires further investigation.