Sempervivum arachnoideum, sometimes known as cobweb house-leek, is a species of flowering plant in the family Crassulaceae, native to the Alps, Apennines and Carpathians. Growing to 8 cm (3 in) tall by 30 cm (12 in) wide, it is a rosette-forming succulent perennial, valued in cultivation for its ability to colonise hot, dry areas via offsets. Its name arachnoideum refers to its furry central rosettes, resembling spider webs. It flowers in July, with pink flowers that are raised on stems and hermaphrodite (having both male and female organs).