''Sempervivum tectorum'', the common houseleek, is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Crassulaceae The Crassulaceae (from Latin ''crassus'', thick), also known as the stonecrop family or the orpine family, are a diverse family of dicotyledon flowering plants characterized by succulent leaves and a unique form of photosynthesis, known as Cr ...

native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and enterta ...

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 tall by broad, it is a rosette-forming succulent

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

, spreading by

offset Offset or Off-Set may refer to: Arts, entertainment, and media * "Off-Set", a song by T.I. and Young Thug from the '' Furious 7: Original Motion Picture Soundtrack'' * ''Offset'' (EP), a 2018 EP by singer Kim Chung-ha * ''Offset'' (film), a 200 ...

s. It has grey-green, tufted, sessile leaves, 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 Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, t ...

, who noted that its leaves are

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a differen ...

, 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:- *bullock's beard *devil's beard *earwort *fuet *healing blade *homewort *imbroke *Jove's beard *Jupiter's eye *poor Jan's leaf *red-leaved houseleek *roof foil *roof houseleek *St. George's Beard *St. Patrick's cabbage *sengreen *Thor's beard *thunderplant *Welcome-home-husband-though-never-so-drunk—a name it sometimes shares with ''

Sedum acre ''Sedum acre'', commonly known as the goldmoss stonecrop, mossy stonecrop,Dickinson, T.; Metsger, D.; Bull, J.; & Dickinson, R. (2004) ROM Field Guide to Wildflowers of Ontario. Toronto:Royal Ontario Museum, p. 243. goldmoss sedum, biting stonec ...

''. * hen and chicks - a name shared with several other plants The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

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

Cultivation and propagation

''Sempervivum tectorum'' is one of several houseleek species to be cultivated. It is valued as

groundcover Groundcover or ground cover is any plant that grows over an area of ground. Groundcover provides protection of the topsoil from erosion and drought. In an ecosystem, the ground cover forms the layer of vegetation below the shrub layer known as ...

for hot, dry places. It has gained the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (No ...

Award of Garden Merit The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. History The Award of Garden Merit ...

.
Sempervivum tectorum multiplies horizontally by propagation of underground roots. Propagation occurs in the spring, when budding occurs. From each mother plant you can get up to 4 new ones. They come off easily taking care not to break the roots. Seeds propagation always works in spring.

Folklore and herbalism

The plant has been traditionally thought to protect against thunderstorms, and grown on house roofs for that reason, which is why it is called House Leek. Many of its popular names in different languages reflect an association with the Roman thunder-god

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandt ...

, notably the Latin ''barba Jovis'' (Jupiter's beard), referred to in the ''Floridus'' traditionally attributed to

Aemilius Macer Aemilius Macer of Verona was a Roman didactic poet. He authored two poems, one on birds (''Ornithogonia''), a translation of a work by Boios, and the other on the antidotes against the poison of serpents (''Theriaca''), which he imitated from th ...

, and its French derivative ''joubarbe'', which has in turn given rise to ''jubard'' and ''jo-barb'' in English; or with the Norse thunder-god

Thor Thor (; from non, Þórr ) is a prominent god in Germanic paganism. In Norse mythology, he is a hammer-wielding god associated with lightning, thunder, storms, sacred groves and trees, strength, the protection of humankind, hallowing ...

as in German ''Donnerbart''. It is also called simply ''thunder-plant''.. Anglo-Saxon ''þunorwyrt'' may have either meaning. However, the association with Jupiter has also been derived from a resemblance between the flowers and the god's beard; in modern times, it has also been called St. George's beard. Bicknell Sempervivuim June 2020

Other common names, such as Anglo-Saxon ''singrēne'', Modern English ''sigrim'', ''sil-green'', etc. and ''aye-green'', refer to its longevity. William Fernie tells a tale in support of this: It has been believed to protect more generally against decay and against witchcraft. Jacob Grimm quotes a Provençal

troubadour A troubadour (, ; oc, trobador ) was a composer and performer of Old Occitan lyric poetry during the High Middle Ages (1100–1350). Since the word ''troubadour'' is etymologically masculine, a female troubadour is usually called a '' trobai ...

: "e daquel erba tenon pro li vilan sobra lur maiso" — "and that plant they keep against evil atop their house." In his ''

Capitulare de villis vel curtis imperii Capitulare may mean: * a legislative text in separate chapters - see capitularium * certain liturgical books, notably: ** Evangeliarium ** Collectarium ** Antiphonary An antiphonary or antiphonal is one of the liturgical books intended for us ...

'',

Charlemagne Charlemagne ( , ) or Charles the Great ( la, Carolus Magnus; german: Karl der Große; 2 April 747 – 28 January 814), a member of the Carolingian dynasty, was King of the Franks from 768, King of the Lombards from 774, and the first Em ...

recommended it be grown on top of houses. In some places, ''S. tectorum'' is still traditionally grown on the roofs of houses. The juice has been used in herbal medicine as an astringent and treatment for skin and eye diseases, including by

Galen Aelius Galenus or Claudius Galenus ( el, Κλαύδιος Γαληνός; September 129 – c. AD 216), often Anglicized as Galen () or Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Considered to be on ...

and

Dioscorides Pedanius Dioscorides ( grc-gre, Πεδάνιος Διοσκουρίδης, ; 40–90 AD), “the father of pharmacognosy”, was a Greek physician, pharmacologist, botanist, and author of '' De materia medica'' (, On Medical Material) —a 5-vo ...

, to ease inflammation and, mixed with honey, to treat

thrush ''The Man from U.N.C.L.E.'' is an American spy fiction television series produced by Metro-Goldwyn-Mayer Television and first broadcast on NBC. The series follows secret agents, played by Robert Vaughn and David McCallum, who work for a secret ...

; however, large doses have an

emetic Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis ...

effect.

Pliny Pliny may refer to: People * Pliny the Elder (23–79 CE), ancient Roman nobleman, scientist, historian, and author of ''Naturalis Historia'' (''Pliny's Natural History'') * Pliny the Younger (died 113), ancient Roman statesman, orator, ...

also mentions it, and

Marcellus Empiricus Marcellus Empiricus, also known as Marcellus Burdigalensis (“Marcellus of Bordeaux”), was a Latin medical writer from Gaul at the turn of the 4th and 5th centuries. His only extant work is the ''De medicamentis'', a compendium of pharmacological ...

listed it as a component in external treatments for contusions, nervous disorders, intestinal problems and abdominal pain, and mixed with honey, as part of the ''antidotum Hadriani'' (Hadrian's antidote), a broad-spectrum palliative for internal complaints. Romans grew the plant in containers in front of windows and associated it with love medicine. Image:Sempervivum Tectorum Greenii, Huntington.jpg, ''Sempervivum tectorum'' "Greenii",

Huntington Desert Garden The Huntington Desert Garden is part of The Huntington Library, Art Collections and Botanical Gardens in San Marino, California. The Desert Garden is one of the world's largest and oldest collections of cacti, succulents and other desert plants, ...

Image:Sempervivum tectorum boutignyanum-1.JPG, ''Sempervivum tectorum boutignyanum'' in flower Image:Sempervivum tectorum (1) 1 (ex Pyrenees).JPG, Rosette with drops of dew Image:Illustration Sempervivum tectorum0.jpg, Illustration from Otto Wilhelm Thomé, ''Flora von Deutschland, Österreich und der Schweiz'', 1885 Image:SempervivumTectorum.jpg, ''Sempervivum tectorum'' with flowers in Uppsala Botaniska Trädgården Image:Sempervivum_tectorum_abl1.JPG, Flower of cultivated variety, photographed in Spain

References

{{Taxonbar, from=Q161724 tectorum Garden plants Plants described in 1753 Taxa named by Carl Linnaeus