This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Usually fleshy herbs with alternate or opposite leaves, often crowded at the extremities of the branches in rosettes; stipules none. Flowers regular, cymose. Sepals free, persistent, 3 to 5, rarely more; petals of the same number, free or connate. Stamens perigynous, or almost hypogynous, as many or twice as many as the petals. Carpels 3 to 5, seldom more, free, many-seeded; seed small, albuminous. About 400 species, in 14 genera, chiefly from temperate and warm countries, rare in Australasia. Most of the members of this family are only suitable for rock-work or in very dry soil, but a few species are familiar, and some have lately been introduced into the geometrical flower-garden to contrast with its highly coloured occupants. Echeveria metallica is one of the most conspicuous of this class.