Everything about Sempervivum totally explained
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're 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.
Typically, each plant grows for several years before flowering. Their hermaphrodite flowers have first a male stage. Then the
stamens curve themselves and spread away from the
carpels at the center of the flower. So
Self-pollination is rather difficult. The colour of the flowers is reddish, yellowish, pinkish, or - seldom - whitish. In
Sempervivum, the flowers are
actinomorphic (like a star) and have more than six petals, while in
Jovibarba, the flowers are campanulate (bell-shaped) and are pale green-yellow with six
petals. 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. This genus is obviously in a not yet stabilized phase of its
evolution and all its members are very 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.
Further Information
Get more info on 'Sempervivum'.
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