Sempervivum globiferum ssp. allionii is a spiky looking lime green rosette that can flush red at its tips. This is a "roller" variety, meaning that it produces lots of round offsets on delicate stolons, that easily roll away from their mother plant.
Sempervivum is a genus of about 40 species of flowering plants in the Crassulaceae family, commonly known as houseleeks. Other common names include liveforever and hen and chicks, a name shared with plants of other genera as well. They are succulent perennials forming mats composed of tufted leaves in rosettes.