Sedum is a large genus of flowering plants in the family Crassulaceae, members of which are commonly known as stonecrops. The genus has been described as containing up to 600 species of leaf succulents that are found throughout the Northern Hemisphere, varying from annual and creeping herbs to shrubs. The plants have water-storing leaves. The flowers usually have five petals, seldom four or six. There are typically twice as many stamens as petals. A number of species, formerly classified as Sedum, are now a separate genus Hylotelephium. Well known European Sedums are Sedum acre, Sedum album, Sedum dasyphyllum, Sedum reflexum (also known as Sedum rupestre) and Sedum hispanicum.
Ornamental Many sedums are cultivated as garden plants, due to their interesting and attractive appearance and hardiness. The various species differ in their requirements; some are cold-hardy but do not tolerate heat, some require heat but do not tolerate cold. Numerous hybrid cultivars have been developed, of which the following have gained the Royal Horticultural Society's Award of Garden Merit:- 'Herbstfreude' ('Autumn Joy') 'Bertram Anderson' 'Matrona' 'Ruby Glow' As food The leaves of all stonecrops are edible. Sedum reflexum, known as "prickmadam", "stone orpine", or "crooked yellow stonecrop", is occasionally used as a salad leaf or herb in Europe, including the United Kingdom. It has a slightly astringent sour taste. Sedum divergens, known as "spreading stonecrop", was eaten by First Nations people in Northwest British Columbia. The plant is used as a salad herb by the Haida and the Nisga'a people. It is common in the Nass Valley of British Columbia. Biting Stonecrop (Sedum acre) contains high quantities of piperidine alkaloids (namely (+)-sedridine, (−)-sedamine, sedinone and isopelletierine), which give it a sharp, peppery, acrid taste and make it somewhat toxic. Traditional S. acre was used to treat epilepsy and skin disease, as well as an abortifacient in ancient Greece. Outright consumption may cause irritations of the mucous membranes, cramps, paralysis, and respiratory paralysis. Roofing Sedum can be used to provide a roof covering in green roofs, where they are preferred to grasses. Ford's Dearborn Truck Plant’s living roof has 10.4 acres (42,000 m2) of sedum. Rolls-Royce Motor Cars plant in Goodwood, England, has a 22,500 square metres (242,000 sq ft) roof complex covered in Sedum, the largest in the United Kingdom. Nintendo of America's roof is covered in some 75,000 square feet of Sedum.