Houseleek

Taxobox
name = Houseleeks

---

image_width = 250px
image_caption = A "Jovibarba"
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Saxifragales
familia = Crassulaceae
genus = "Sempervivum"
genus_authority = L.
subdivision_ranks = Species
subdivision = "Sempervivum altum"
"Sempervivum arachnoideum"
"Sempervivum armenum"
"Sempervivum atlanticum"
"Sempervivum ballsii"
"Sempervivum borissovae"
"Sempervivum calcareum"
"Sempervivum cantabricum"
"Sempervivum caucasicum"
"Sempervivum ciliosum"
"Sempervivum davisii"
"Sempervivum dolomiticum"
"Sempervivum erythraeum"
"Sempervivum glabrifolium"
"Sempervivum ingwersenii"
"Sempervivum juvanii"
"Sempervivum kindingeri"
"Sempervivum kosaninii"
"Sempervivum leucanthum"
"Sempervivum macedonicum"
"Sempervivum marmoreum"
"Sempervivum minus"
"Sempervivum montanum"
"Sempervivum nevadense"
"Sempervivum octopodes"
"Sempervivum ossetiense"
"Sempervivum pittonii"
"Sempervivum pumilum"
"Sempervivum sosnowskyi"
"Sempervivum tectorum"
"Sempervivum thompsonianum"
"Sempervivum transcaucasicum"
"Sempervivum wulfenii"
"Sempervivum zeleborii"

Houseleeks or Liveforever ("Sempervivum") are a genus of about 40 species of succulent plants of the Crassulaceae family which grow in rosettes. Another name used for some species (and also for some plants in other related genera) is Hen and chicks.

Habitat

They occur from Morocco to Iran, through the mountains of Iberia, the Alps, Carpathians, Balkan mountains, Turkey, the Armenian mountains, and the Caucasus. Their ability to store water in their thick leaves allows them to live on sunny rocks and stony places in the montane, subalpine and alpine belts.

Subtropical origin

Like some other plants of Southern Europe, their ancestors have likely a subtropical origin. Morphologically, they are closely linked with the genera "Jovibarba", "Aeonium", "Greenovia", "Aichryson", and "Monanthes", occurring mainly in Macaronesia (Azores, Canary Islands, Cape Verde, Madeira). Some botanists include some or all of these genera within a wider interpretation of "Sempervivum", particularly "Jovibarba".

Origin of name

The name "Sempervivum" has its origin in the Latin "Semper" ("always") and "vivus" ("living"). "Sempervivum" are called "always living" because this perennial plant keeps its leaves in winter and is very resistant to difficult conditions of growth.

Growth and reproduction

Houseleeks grow as tufts of perennial but monocarpic rosettes. Each rosette propagates Asexually by lateral rosettes (offsets, "hen and chicks"), by splitting of the rosette (only "Jovibarba heuffelii") or sexually by tiny seeds.

s. After flowering, the plant dies, usually leaving many offsets it has produced during its life.

Identification

The genus "Sempervivum" is easy to recognize, but its species are often not easy to identify. Even one single clone can look very different under various growth conditions (modifications) or different times of the year. The members of this genus are very similar and closely linked to each other. As a consequence, many subspecies, varieties, and forms were described, without well-defined limits between them. As a second consequence, there are a high frequency of natural hybrids in this genus and the possibility of back-crossings of these. However, more or less 40 species can be individualized in the whole area of the genus, but there are many more local populations, without nomenclatural valour but with sometimes their own characters.

In the Alps, for example, the most distributed species are "Sempervivum tectorum" (Common Houseleek, sometimes called "Sempervivum alpinum"), "Sempervivum montanum" (Mountain Houseleek) and "Sempervivum arachnoideum" (Cobwebbed Houseleek), each one with several subspecies. More local are the yellow-flowered "S. wulfenii" and "S. grandiflorum", and the beautiful Limestone Houseleek ("S. calcareum"). More rare are "S. dolomiticum" and mainly "S. pittonii". "S. pittonii" is a small yellow-flowered jewel which grows only on two mountains slopes near Kraubath in the Mur valley in Austria and is very threatened.

On roofs or old walls "S. tectorum" can be found, more or less wild, very far out of its natural area. It is a very old medicinal and witch-plant. Some superstitious people believe that this plant is able to protect a house from lightning.

Garden plants

Although their subtropical cousins are very frost-sensitive, Sempervivums are among the most frost-resistant succulents, making them popular garden plants. They require only moderate water and some protection from extreme exposure to the sun.

Sempervivums grow very well in dry conditions. Despite this if Sempervivums are grown in normal flower beds among other cultivated plants there can be a problem. If the flower beds are not particularly dry other plants may grow more strongly than the Sempervivums and overshadow them. Other plants may need to be removed, cut back or tied out of the way.

"Semp-lovers" are numerous and often have many different cultivars in their collections. Sempervivums are very variable plants and hence hundreds, maybe thousands of cultivars were created, but a lot of them are not much different from each other. The main interest of these cultivars are not their flowers, but form and colour of the rosette-leaves. The most colourful time is generally from March till June.

External links

*http://sempervivophilia.stalikez.info/ from Gérard Dumont (in French and in English; some pages in German and Spanish. Photos of the species in their natural habitats)
*http://www.sempervivum.ru/ (mostly in Russian)