Sempervivum Tectorum [sem-per-VEE-vum, tek-TOR-um] is a flowering Sempervivum plant species from the family Crassulaceae. While the plant is native to southern Europe, it is cultivated in the entire continent due to its unique appearance and traditional beliefs attached to it. For example, in the Roman tradition, the plant is believed to protect buildings from lightning strikes – many of the plant’s common names reflect this belief.