Native to mountains of Europe. Form tightly packed rosettes of fleshy, evergreen leaves; spread by little offsets that cluster around parent rosette. Clustered, star-shaped summer flowers in white, yellowish, pink, red, or greenish; pretty in detail but not showy. Blooming rosettes die after setting seed, but offsets (easily detached and replanted) carry on. There are many species; all are good in rock gardens, pots, even in pockets in boulders or pieces of porous rock. Need excellent drainage. Water only to prevent shriveling.
S. arachnoideum. COBWEB HOUSELEEK. Gray-green rosettes of many leaves are joined by fine hairs for a cobweb-covered look. Larger rosettes (to 2 in. wide) are surrounded by a host of smaller ones. Spreads slowly to make a dense mat to 1 ft. or wider. Bright red flowers on 4- to 6-in. stems. 'Cebennense' has cobwebby green leaves with burgundy tips. Leaves of 'Rubrum' are flushed with red in spring.
S. hybrids. Most selections sold fall into this category. All form crowded rosettes that vary mainly in color and leaf shape. 'Oddity' is the most widely sold, with burgundy-tipped green tubular leaves; grows 8 in. high, 12 in. wide. 'Black' has deep maroon leaves with contrasting green new growth. 'Carmen' has large rosettes of green leaves tipped in red. Leaves of 'Krebs' are chocolatey green; those of 'Rubikon Improved' are red.
S. tectorum. HEN AND CHICKENS. Gray-green, 2- to 5-in.-wide rosettes spread quickly to form clumps to 2 ft. or wider. Leaves have red-brown, bristly tips. Red or reddish blossoms are borne on stems to 2 ft. tall. An old-time passalong plant.