As a comment about Jovibarbas (Sempervivum heuffelii)
"Jovibarba ("beard of Jupiter") is a small genus of three species of succulent flowering plants in the family Crassulaceae, endemic to mountainous regions in the southeastern quadrant of Europe. The genus is sometimes classified as a subgenus of Sempervivum, to which it is closely related. Jovibarba have pale-greenish-yellow or yellow actinomorphic flowers with about six petals, while Sempervivum have generally pinkish flowers with around twice as many petals, which open more widely than jovibarba flowers. The common name hen and chicks is applied to some Jovibarba species (and also species in several other Crassulaceae genera).
Jovibarbas, like sempervivums, reproduce via offsets in addition to producing seeds via sexual reproduction. To propagate it must be split with a knife. Offsets survive the main rosette, which is monocarpic."
Taken from wikipedia's page at: http://en.wikipedia.org/wiki/Jovibarba