This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Europe and Western Asia are the regions in the North Temperate Zone in which alone to-day this plant is known. The Houseleek is not a native, and its existence depends largely on the former use to which it was put as a source of ointment. In every village where there still remain old-fashioned thatched cottages, especially in the west, one may be sure to find one or more with some traces of a roof-garden, made up of Houseleek or Stonecrop. Indeed it is quite a feature of the village community, and affords evidence of the picturesque nature of our country places, in spite of many drawbacks, caused by poverty or the lack of an artistic sense in constructing the dwelling of the labourer.
The perennial nature of this plant is indicated by the first, and the usual roof habitat by its second Latin name. It is an erect plant, very succulent (assisting water storage), with thick, fleshy leaves, fringed with a ring of hairs, of a reddish tint, the radical leaves arranged in a rosette, stalkless, wedge-shaped, flat above, white below, and smooth or glabrous.
The flowers are numerous and close, turned all one way, usually erect, and reddish or pink. The calyx is 12-partite, sticky, fringed with hairs, purple above. The corolla has 12 petals, which are twice as long as the calyx, of a purplish colour. There are 12 stamens with purple anthers. The capsules are numerous, flattened at the border, and open inwards, in the form of follicles with many seeds.
The plant is tall, reaching a height of 12 in. or more. It flowers from June to August. Houseleek is perennial or biennial, and reproduced by division.
The colour of the flowers, which are purple, depends on their adaptation to a narrow or wide circle of visitors. The honey lies hidden, and the flowers are visited by bees, Lepidoptera, and long-tonorued flies. Whilst there are 10 stamens in Sedum, in Sempervivum there are 12-40. The an-thersopen first, butself-pol-lination is not impossible.
The follicle splitting open allows the numerous seeds to fall over a wide compass around the parent plant when shaken out by the wind.
Houseleek is a mural or roof plant, and requires for its growth a certain amount of humus.
Endophyllum sempervivi, a cluster-cup fungus, noteworthy since it is sunk in the surface of the leaf, is found upon Houseleek, and also a mould Phytophthora omnivora. No insect makes a food-plant of it.
Sempervivum, Pliny, is Latin for livelong, and tectorum alludes to its roof habitat.
Houseleek goes by the following names: Aye-green, Bullock's-eye, Cyphel, Fews, Foos, Fouets, Fow, Fuit, Full, Healing Blade, Hockerie-topner, Homewort, House-green, Huslock, Imbreke, Jo-barbe, Jubard, Jupiter's Heard, Jupiter's Eye, Poor Jan's Leaf, Sel-green, Sengreen, Sigrim, Sil-green, Simgreen, Singreen, Sinna-green, Sungreen, Suphelt, Thunder-plant. Homewort was the Saxon name for it. Cockayne says planted on a roof it protected from thunder and lightning. Because associated with the evil one it was called Devil's Beard.
Photo. J. H. Crabtree - Houseleek (Sempervivum tectorum, L.)
Houseleek was used in Italy as a love charm. There are locally antipathies against uprooting and even allowing it to bloom. It was used in heny greyne, i.e. megrim, used for neuralgia. An ointment for scalds and burns is prepared from it. The plant is astringent. It is planted on roofs and walls as an ornament.
Essential Specific Characters: 115. Sempervivum tectorum, L. - Leaves fleshy, succulent, fringed at the margin, tufted, flowers purple, petals 12, ciliate.