SEMPERVIVUM, LIVE-EVER, or House-leek; a genus of the dodecagynia order, belonging to the dodecandria class of plants. There are twelve species, four of which are natives of Britain; all of them hardy ever-green perennials, formed of roundish clusters of succulent smooth leaves in expanded open heads, producing very spreading off-shoots, and erect succulent stalks from six to twelve inches high, with flowers of a deep-red or yellow colour.—Besides these, there are two species, natives of warm countries; the arborescens, or tree house-leek; and the canariensis, or Canary shrub by house-leek. The former rises with an upright smooth fleshy stem, six or eight feet high, with the branches terminated by large clustering heads of spear-shaped bright-green leaves; and from the centre of the heads large pyramidal spikes of bright yellow flowers. There is a variety with variegated leaves and white flowers, exceedingly ornamental. The canariensis rises with an upright succulent rugged stalk, half a yard or more high, appearing ragged with the rudiments of past foliage, having the top crowned by large globular heads of retuse succulent leaves; and from the centre of the head a long pyramidal spike of greenish-coloured flowers.—They are all easily propagated by off-shoots, cuttings, or seeds. The four hardy species will thrive on any old wall; but the other two being tender, must be sheltered in the green-house. The leaves of the common house-leek have been recommended as refrigerant, though their sensible qualities discover no great signs of any virtue of this kind; their taste being herbaceous, with a slight degree of pungency. It is remarkable of this plant, that its juice, purified by filtration, when it appears of a dilute yellowish colour, upon the admixture of an equal quantity of rectified spirit of wine, forms a beautiful white, light coagulum, like the finer kinds of pomatum, which proves extremely volatile; so that, when freed from the aqueous phlegm, and exposed to the air, it in a very little time totally exhales. Hence some have concluded that the juice contained a volatile alkaline salt; but nothing of this kind is discovered by any other trial, and there are many substances besides these salts which coagulate with spirit of wine.