Petrosedum is a genus of succulent flowering plants in the family Crassulaceae (the stonecrop family), order Saxifragales. The genus was segregated from the large, cosmopolitan, and polyphyletic genus Sedum, where its members had previously been grouped under series Rupestria. Petrosedum belongs to the subfamily Sempervivoideae, tribe Semperviveae, alongside two other related genera.
Members of Petrosedum are perennial succulents typically forming low, prostrate mats or cushions up to about 10 cm tall. They have sprawling stems bearing stiff, needle-like leaves that superficially resemble spruce foliage. Foliage color ranges from blue-gray and gray to light green and yellow depending on species and growing conditions. The flowers are yellow and borne in terminal cymes — a characteristic shared with their former placement in Sedum.
The genus is primarily distributed across Europe, from northern to southern regions, with particular diversity in the Mediterranean basin and mountain ranges such as the Alps and Pyrenees. Most species favor rocky, well-drained soils and dry habitats — the "petro-" prefix reflects this affinity for stony ground.
The best-known member, Petrosedum rupestre (reflexed stonecrop or Jenny's stonecrop), is widely cultivated as a drought-tolerant ornamental in gardens, rock gardens, green roofs, and containers. It is also occasionally used as a culinary herb in parts of Europe, with leaves described as slightly astringent or sour. The genus was originally described with eleven species; current circumscription recognizes around two dozen species and nothotaxa (hybrid taxa).
Etymology
The name Petrosedum combines the Greek petros (rock, stone) with Sedum, the genus from which it was segregated, reflecting the group's affinity for rocky habitats. The "petro-" prefix distinguishes it from the broader Sedum aggregate while retaining its heritage within the stonecrop lineage.
Distribution
Petrosedum species are native primarily to Europe, with the best-known member (Petrosedum rupestre) occurring across northern, central, and southern Europe. The genus shows particular diversity in rocky habitats of the Mediterranean region and mountain ranges including the Alps and Pyrenees.
Taxonomy Notes
Petrosedum was segregated from the large, cosmopolitan, and polyphyletic genus Sedum, where its members had been placed under series Rupestria. It is placed in family Crassulaceae, subfamily Sempervivoideae, tribe Semperviveae, and was originally described with eleven species. GBIF recognizes the genus as accepted within order Saxifragales. The genus includes both species and hybrid nothotaxa (denoted by ×).
Cultivation
Petrosedum rupestre and related species are popular drought-tolerant ornamentals suited to rock gardens, green roofs, containers, and ground cover plantings. They are propagated readily from stem cuttings. Named cultivars with variegated or colored foliage exist. Plants are susceptible to fasciation (cristate forms), producing attractive sculptural growth, though normal shoots must be removed promptly to maintain these forms as they revert readily. Some species are occasionally used as edible herbs in Europe.
