(Sempervivum tectorum) Common houseleek

Sempervivum tectorum (common houseleek) is a species of flowering plant in the familyCrassulaceae, native to the mountains of southern Europe, cultivated in the whole of Europe for its appearance and a Roman tradition claiming that it protects buildings against lightning strikes.

Description
Growing to 15 cm (6 in) tall by 50 cm (20 in) broad, it is a rosette-forming succulent evergreen perennial, spreading by offsets. It has grey-green, tufted, sessile leaves, 4–10 cm (2–4 in) in diameter, which are often suffused with rose-red. In summer it bears clusters of reddish-purple flowers, in multiples of 8-16, on hairy erect flat-topped stems. The species is highly variable, in part because hundreds of cultivars have been propagated, sold, and traded for nearly 200 years.

Sempervivum tectorum was described in 1753 by Linnaeus, who noted that its leaves are ciliate, that is, fringed with hairs.

Names
This plant has been known to humans for thousands of years, and has attracted many common names and traditions. In addition to common houseleek, names include variations of the following:-

• Welcome-home-husband-though-never-so-drunk—a name it sometimes shares with Sedum acre.
• hen and chicks - a name shared with several other plants

The specific epithet tectorum means "of house roofs", referring to a traditional location for these plants.

Cultivation
S. tectorum is one of several houseleek species to be cultivated. It is valued as groundcover for hot, dry places. It has gained the Royal Horticultural Society's Award of Garden Merit.
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https://en.wikipedia.org/wiki/Sempervivum_tectorum