This section is from the book "Wayside And Woodland Blossoms", by Edward Step. Also available from Amazon: Wayside And Woodland Blossoms: A Guide To British Wild-Flowers.
Although the Houseleek is not a true native of Britain it has been so long established on old walls and the roofs of out-houses that it is quite a familiar object in a country ramble. As its scientific name (from semper, always, and vivum, fresh, green) indicates, it dies hard, and alike endures frost and drought. The story is told of one that a botanist tried hard for eighteen months to dry for his herbarium, but failing in his object planted it again, and it grew as though nothing had occurred to interfere with its ordinary life. The leaves are borne on the flowerless stems in the form of a rosette, the oldest flat, the youngest erect; thick, fleshy, the edges purple, tips sharply pointed. Flowering stems with alternate leaves; flowers dull purple in cymes. Sepals twelve, petals twelve, stamens twenty-four, but twelve of these are imperfect or aborted. Flowers June and July.