There are many species in the Sempervivum genus, each unique and with particular properties.  Noted by Linnaeus in 1757, the genus name translates to "always living," a reference to the plants' hardy, drought-tolerant nature, enabling it to survive in both intense heat and frost.  They are also known as houseleeks, hens, chicks, or hen's nests in some areas.

While more general than previous posts, being a genus, rather than a species, I will endeavor to include the same level of information.  There are about 50 known individual species and around 3000 different cultivars in the genus, many of which share characteristics in color, leaf shape and count, and ethnobotanic associations.  

Species in the Sepmervivum genus have been found across Eurasia, though the majority seem to be concentrated in central Europe, natural habitats often being at 3000-8000 ft above sea level, in mountainous alpine regions.  They are also monocarpic plants, meaning that once they have flowered and produced seeds, they die.  Their rich colors often only appear when grown in full sun, allowing the reds, pinks, and yellows to join the greens seen in cultivars generally grown away from direct sunlight.  There are many variants on these color combinations and even within the same plant, depending on age of the plant, location, and habit conditions.  Some change color gradient direction, others change color all together or the tips become darker or lighter over time.  The flowers often produce a star-shaped fruit and 

The leaves of several species have injury-healing properties, much like Aloe. Indeed, in Pliny the Elder's Naturalis Historiae, he notes that the juice from the plants' leaves can be used to treat a variety of skin complaints, including "burns, scalds, corns, calluses, warts, ringworm, shingles (localized infection with the chickenpox virus), insect stings shingles, itching and burning of the eyes, and earache," (succulent-plant.com).  Likewise, Discorides recorded in his Materia Medica that the plant's leaves, when crushed and added to wine could and would remove intestinal parasites from the drinker's body. Sempervivum's medicinal and cultural-spiritual properties are especially noted in the Balkans where they are both grown in case they're needed in homegardens and held in high regard as apotropaions or Evil-eye amulets.  

Disclaimer: It should also be noted that the sites I found did not advocate for current medical Sempervivum uses. 

To Romans, it was both useful against their crops being infested by caterpillars and were considered sacred to Jupiter.  To Nordic peoples, it was sacred to Thor, both cultures believing the plant to resemble the beard of their particular deity.  This is also why one speices, Jovibarba (L.) Iovis barbam translates to Jupiter's Beard.

Till tomorrow,

Katheryn

Sources: 

1. http://succulent-plant.com/families/crassulaceae/sempervivum.html (Accessed 7.22.15)

2. http://www.drought-smart-plants.com/sempervivum-picture-gallery4.html#axzz3gh6eKCeI (Accessed 7.22.15)

3. Ethnobotany and Biocultural Diversities in the Balkans: Perspectives on Sustainable Rural Development and Reconciliation. Andrea Pieroni, Cassandra L. Quave . Springer, Nov 14, 2014