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.
Of the eight British species of Sedum, and the two or three additional kinds that have escaped from gardens and become locally naturalized, this is the best known. Rocks and old walls are its favourite resorts, the stems growing downwards and curving outwards. The leaves are small, thick, produced into a kind of spur at the base, and closely pressing the older on the newer. The calyx is in one with five lobes, the corolla consists of five distinct golden yellow petals: stamens ten, with yellow anthers; carpels five, united at their bases. Flowers June and July. Another popular name for it is Wall Pepper, both names being due to the acrid taste.
The scientific name is from the Latin sedeo, to sit, from the peculiar habit of the plant.
Biting Stonecrop. Wall pepper.