“ Many species spread by means of a creeping much-branched rootstock, or as in house-leek, by runners which perish after producing a terminal leaf-rosette. In other cases small portions of the stem or leaves give rise to new plants by budding, as in Bryophyllum, where buds develop at the edges of the leaf and form new plants. ”

“ Correlated with their life in dry situations, the bulk of the tissue is succulent, forming a water-store, which is protected from loss by evaporation by a thickly cuticularized epidermis covered with a waxy secretion which gives a glaucous appearance to the plant. ”

“ Sempervivum has about 50 species in the mountains of central and southern Europe, in the Himalayas, Abyssinia, and the Canaries and Madeira; S. tectorum, common house-leek, is seen often growing on tops of walls and house-roofs. The hardy species will grow well in dry sandy soil, and are suitable for rockeries, old walls or edgings. They are readily propagated by offsets or by seed. ”