Sedum, commonly known as stonecrops, is a large genus of leaf succulents in the family Crassulaceae, order Saxifragales. Described by Carl Linnaeus in 1753, the genus encompasses roughly 488 accepted species according to Plants of the World Online (Kew), with GBIF tracking over 800 descendant taxa including subspecies and varieties. Plants range from low-growing annual and creeping herbs to small shrubs, all sharing the characteristic water-storing fleshy leaves — flat or rounded depending on species — that are the hallmark of succulent growth.
Flowers are typically star-shaped with five petals (occasionally four or six) and twice as many stamens as petals, borne in flat-topped or branched cymes. Stems are often reddish or glaucous, and the foliage may turn brilliant shades of copper, red, or bronze under stress or in autumn. The genus name derives from the Latin sedeo, meaning "to sit," a reference to the way many species sprawl and cling to bare rock surfaces.
Most species grow in rocky, well-drained, often poor soils, from coastal cliffs and dry meadows to alpine scree and sunny walls. The natural range spans temperate to subtropical regions of the Northern Hemisphere — most diversely in the Mediterranean, Central America, the Himalayas, and East Asia — with outlying representatives in Africa and South America.
Horticulturally, sedums rank among the most versatile and widely grown succulents in temperate gardens. Larger, upright forms such as the cultivar 'Herbstfreude' (Autumn Joy) are prized as late-season perennials with long-lasting flower heads attractive to pollinators; smaller, mat-forming species are staple plants for rock gardens, green roofs, and container plantings. Their drought tolerance and minimal soil requirements make them among the lowest-maintenance ornamentals available.
Etymology
The genus name Sedum is derived from the Latin verb sedeo, meaning "to sit." This name was applied by Carl Linnaeus in 1753 and refers to the characteristic habit of many species to sit and sprawl close to — or directly on — bare rock surfaces. The common name "stonecrop" similarly alludes to the ability of these plants to colonize rocky outcrops and walls where little else will grow.
Distribution
Sedum has a broad distribution across temperate and subtropical regions of the Northern Hemisphere, with outliers in tropical mountains, sub-Saharan Africa, and South America. The genus is most species-rich in the Mediterranean basin, Central America (particularly Mexico, the centre of diversity for subgenus Sedum), the Himalayas, and East Asia. The Eurasian subgenus Gormania has its primary centre in Eurasia and a secondary centre in western North America.
Approximately 500 species occur globally, with native and naturalized species found throughout North America. Many European species — including Sedum acre, S. album, S. hispanicum, and S. telephium — have become widely naturalized beyond their native ranges, establishing on walls, roadsides, and disturbed rocky habitats across temperate zones worldwide.
Taxonomy
Sedum was established by Linnaeus in Species Plantarum (1753) and is the largest genus in Crassulaceae. Plants of the World Online (Kew) currently recognizes 488 accepted species. The genus has historically been broadly circumscribed: POWO lists 42 heterotypic synonyms representing former genera now folded into Sedum, including Gormania, Mucizonia, Diamorpha, and Sempervivella.
Conversely, molecular phylogenetic studies have shown that Sedum as traditionally defined is not monophyletic, leading to the recognition of several segregate genera. The most prominent is Hylotelephium, which accommodates many of the larger, upright "border sedum" species formerly placed in Sedum (including the well-known 'Autumn Joy' group). Numerous other smaller genera have been carved out of Sedum, and many taxa remain provisionally classified there pending nomenclatural resolution, adequate morphological data, or further molecular sampling. New species continue to be described, particularly from China and Central and South America.
Ecology
Sedum species are characteristic plants of rocky, nutrient-poor, well-drained habitats: cliff faces, talus slopes, rocky meadows, stone walls, and coastal outcrops. Their succulent leaves allow them to withstand prolonged drought, and their shallow root systems let them colonize thin soils where competition from grasses and forbs is low.
Several species play notable ecological roles as larval host plants for specialist butterflies. Sedum spathulifolium is the sole food plant of the endangered San Bruno elfin butterfly in coastal California, while Sedum lanceolatum hosts Parnassius smintheus (the Rocky Mountain parnassian) in alpine meadows. Flowers are rich nectar sources for bees and other pollinators, and the persistent seed heads of larger species provide food for seed-eating birds into winter.
Cultivation
Sedums are among the most adaptable and low-maintenance plants for temperate gardens. They require full sun to light partial shade and excellent drainage; a gritty or sandy soil (or a commercial cactus mix) is preferable to rich, moisture-retentive loam, in which they may rot at the crown. Most species are highly drought-tolerant once established and need little or no supplemental irrigation in temperate climates. USDA hardiness zones 3a–9b cover the majority of cultivated forms.
Landscape applications span a wide range: low-growing mat-forming species are used in rock gardens, alpine troughs, between paving stones, and as drought-tolerant lawn alternatives; medium-height forms are used as edging and border perennials; and the genus is particularly valued for extensive green roof systems, where its low weight, shallow root depth, and drought tolerance suit the constraints of roof substrates. The genus is also popular in container plantings and hanging baskets.
Notable cultivars recognized by the Royal Horticultural Society include 'Herbstfreude' ('Autumn Joy'), 'Bertram Anderson', 'Matrona', and 'Ruby Glow'.
Propagation
Sedum is easily propagated by multiple vegetative methods as well as from seed. Stem cuttings taken in spring or early summer root readily in gritty compost with minimal moisture. Individual leaves detached cleanly at the base will also produce new plantlets when laid on the surface of barely moist compost — fallen leaves naturally self-propagate in this way around established clumps. Division of established clumps in spring or early summer is straightforward; larger divisions can be replanted directly in the garden, while smaller pieces benefit from a short period in a pot before being planted out.
Seed can be sown on the surface of moist compost in a cool greenhouse in spring (surface sowing is important as the tiny seeds need light to germinate). Seedlings are slow to develop and are best grown on under protection for their first season.
Cultural Uses
The leaves of many Sedum species are edible and have a long history of use as food plants in Europe and Asia. Sedum reflexum (reflexed stonecrop) has been used as a salad herb in European folk cuisine, with young leaves chopped finely and added raw to salads or cooked as a pot herb. Leaves are nutritionally notable for their calcium content (recorded at approximately 3,820 mg per 100 g dry weight in some species). A caution applies to yellow-flowered species, which can cause digestive upset if consumed in quantity.
Beyond food, Sedum's practical uses include an established role in green infrastructure. The genus is the dominant plant group on extensive green roofs worldwide, valued for its ability to form a stable, self-maintaining cover on lightweight substrates without irrigation in many climates. This application has expanded significantly in urban sustainability projects across Europe and North America.
