Difference between revisions of "Sempervivum"

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{{SPlantbox
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| name = ''LATINNAME''  <!--- replace LATINNAME with the actual latin name -->
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|familia=Crassulaceae
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|genus=Sempervivum
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| growth_habit = ?  <!--- tree, shrub, herbaceous, vine, etc -->
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|common_name=Houseleek, Hens and chickens
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| high = ?  <!--- 1m (3 ft) -->
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|habit=cacti-succulent
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| wide =     <!--- 65cm (25 inches) -->
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|lifespan=perennial
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| origin = ?  <!--- Mexico, S America, S Europe, garden, etc -->
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|life_ref=Flora - A Gardener's Encyclopedia
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| poisonous =     <!--- indicate parts of plants which are known/thought to be poisonous -->
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|exposure=part-sun
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| lifespan =    <!--- perennial, annual, etc -->
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|water=moderate, dry
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|water_ref=Wikipedia
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| features =    <!--- flowers, fragrance, fruit, naturalizes, invasive -->
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|image=Sempervivum tectorum.JPG
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|image_caption=Hen & Chicks (Sempervivum tectorum)
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'''Houseleeks''' or '''Liveforever''' (''Sempervivum,'' {{pron-en|sɛmpəˈvaɪvəm}})<ref>''Oxford English Dictionary,'' 2nd Edition 1989</ref> are a [[genus]] of about 40 [[species]] of [[succulent]] plants of the [[Crassulaceae]] family which grow in [[Rosette (botany)|rosettes]]. Another name used for some species (and also for some plants in other related genera) is [[Hen and chicks]].
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They occur in N Africa and S Europe to Iran. 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.
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Houseleeks grow as tufts of [[Perennial plant|perennial]] but [[monocarpic]] [[Rosette (botany)|rosettes]]. Each rosette propagates [[Asexual reproduction|Asexually]] by lateral rosettes ([[offsets]], "[[hen and chicks]]"), by splitting of the rosette (only ''[[Jovibarba|Jovibarba heuffelii]]'') or [[Sexual reproduction|sexually]] by tiny seeds.
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Typically, each plant grows for several years before flowering. Their hermaphrodite flowers have first a male stage. Then the [[stamen]]s curve themselves and spread away from the [[carpel]]s 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 flower|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 [[petal]]s. After flowering, the plant dies, usually leaving many offsets it has produced during its life.
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"Semp-lovers" are numerous and often have many different [[cultivar]]s 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.
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Sempervivum (Latin, living forever). Crassulaceae. Houseleek. Thick fleshy usually stemless, perennial herbs or subshrubs which are used for carpet-bedding, rockeries, and the like. See [[Succulents]] for culture.
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Sempervivum (Latin, living forever). Crassulaceae. Houseleek. Thick fleshy usually stemless, perennial herbs or subshrubs which are used for carpet-bedding, rockeries, and the like. See Succulents (p. 2672, Vol. V) for culture.
 
  
 
Leaves alternate, thick-fleshy, often revolute: cymes panicled, usually densely: fls. white, rose, green, yellow, or purple; calyx 6- to many-cleft or -parted, rarely 5- cleft; petals 6 to many, free or connate at the base, oblong or lanceolate; stamens double as many as the petals, rarely the same number, free; ovary with as many carpels as petals, free or the base or up to the middle immersed in the calyx-tube: fr. many-seeded follicles.—About 65 species, widely scattered in the mountains of the Old World. The genus was monographed (horticulturally) by J. G. Baker in Gardener's Chronicle for 1879, and his treatment has been followed here to some extent with the addition of several species and slight modifications to meet more recent knowledge of the genus. Sempervivum is closely related to Sedum, but the floral parts are multiples of 6 or some larger number, while the floral parts of Sedum are in 5's. The genus is a difficult one for the botanist, and the specific limits are very uncertain and unsatisfactory, no two authors agreeing. The key given will undoubtedly prove faulty, but is an attempt to simplify the determination of the species.
 
Leaves alternate, thick-fleshy, often revolute: cymes panicled, usually densely: fls. white, rose, green, yellow, or purple; calyx 6- to many-cleft or -parted, rarely 5- cleft; petals 6 to many, free or connate at the base, oblong or lanceolate; stamens double as many as the petals, rarely the same number, free; ovary with as many carpels as petals, free or the base or up to the middle immersed in the calyx-tube: fr. many-seeded follicles.—About 65 species, widely scattered in the mountains of the Old World. The genus was monographed (horticulturally) by J. G. Baker in Gardener's Chronicle for 1879, and his treatment has been followed here to some extent with the addition of several species and slight modifications to meet more recent knowledge of the genus. Sempervivum is closely related to Sedum, but the floral parts are multiples of 6 or some larger number, while the floral parts of Sedum are in 5's. The genus is a difficult one for the botanist, and the specific limits are very uncertain and unsatisfactory, no two authors agreeing. The key given will undoubtedly prove faulty, but is an attempt to simplify the determination of the species.
  
 
Sempervivums are mostly hardy perennials and stemless, and increase by rosettes (Fig. 3602) which are sent out from the parent plant, thereby suggesting the popular name "hen-and-chickens." The leaves are thick, short, and succulent. The flowers, which are borne in panicled cymes, are mostly yellow, greenish yellow, or some shade of rose or purple, rarely white. The individual flowers are larger than those of sedum, but the clusters are less showy. Houseleeks are cultivated more for foliage than for flowers. They are not used for as great a variety of purposes as sedums, but they are popular for carpet-bedding, rockwork, and covering dry banks and bare sandy wastes. They are of the easiest culture and are quickly multiplied by means of the offsets or rosettes. They may be used alone for permanent carpet-beds, and for this special purpose are preferable to the more popular but tender echeveria. The foliage remains green all winter. The leaves are often spotted with red toward the tip, and this color is brighter if the plants have full sunlight. The names "houseleek" and "hen-and-chickens" are loosely applied to the whole genus. If these names are to be restricted, the former should be used for Sempervivum tectorum and the latter for S. soboliferum. The common species, which grows on the roofs of houses in Europe, is S. tectorum. In the case of S. soboliferum the young rosettes are attached to the parent plant by a more slender thread than usual and more easily detach themselves and roll about. The spider-web species, of which S. arachnoideum is the commonest, are the prettiest, of them all, by reason of the webs that cover the young rosettes. These coverings are made by the plants themselves and are incidental to development, but in some species are not strongly developed and in all the group are less noticeable in the old rosettes.
 
Sempervivums are mostly hardy perennials and stemless, and increase by rosettes (Fig. 3602) which are sent out from the parent plant, thereby suggesting the popular name "hen-and-chickens." The leaves are thick, short, and succulent. The flowers, which are borne in panicled cymes, are mostly yellow, greenish yellow, or some shade of rose or purple, rarely white. The individual flowers are larger than those of sedum, but the clusters are less showy. Houseleeks are cultivated more for foliage than for flowers. They are not used for as great a variety of purposes as sedums, but they are popular for carpet-bedding, rockwork, and covering dry banks and bare sandy wastes. They are of the easiest culture and are quickly multiplied by means of the offsets or rosettes. They may be used alone for permanent carpet-beds, and for this special purpose are preferable to the more popular but tender echeveria. The foliage remains green all winter. The leaves are often spotted with red toward the tip, and this color is brighter if the plants have full sunlight. The names "houseleek" and "hen-and-chickens" are loosely applied to the whole genus. If these names are to be restricted, the former should be used for Sempervivum tectorum and the latter for S. soboliferum. The common species, which grows on the roofs of houses in Europe, is S. tectorum. In the case of S. soboliferum the young rosettes are attached to the parent plant by a more slender thread than usual and more easily detach themselves and roll about. The spider-web species, of which S. arachnoideum is the commonest, are the prettiest, of them all, by reason of the webs that cover the young rosettes. These coverings are made by the plants themselves and are incidental to development, but in some species are not strongly developed and in all the group are less noticeable in the old rosettes.
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S. affine, Lamotte, is offered in the trade as having dark green rosettes marked with rose: fls. red. Eu. The botanical description is not available and the species is not treated in recent European floras.—S. atropurpureum, Hort., is offered in the trade as having rosettes washed with purple: fls. red.—S. chrysanthoides, Hort., is offered in the trade as a form with white fls.—S. ciliosum, Craib. Barren rosettes more or less flat, up to 1 1/4 in. diam.: lvs. oblong-lanceolate, more or less acuminate, up to 3/4 in. long, keeled beneath, conspicuously long white-ciliate toward the apex, pubescent above, outer lvs. red-tinted; cauline lvs. imbricate, tip red-suffused: fl.- sts. about 2 in. high, bearing about 6 subsessile fls.: fls. about 1 in. across, pale green, 9-11-merous; calyx-segms. oblong-lanceolate, acute, glandular-pubescent; petals linear, glandular-pubescent externally. Hab.(?). Grown in botanic gardens.—S. colchicum, Hort., is offered in the trade.—S. commutatum, Hort., is offered in the trade.—S. Delpontii, Hort., is a trade name.—S. elegans, Lagg. Rosettes small, about 1/2 in. diam., the young ones on short shoots forming a mat: lvs. linear-lanceolate, cuspidate, short-villous, weakly cobwebbed, pale green, slightly ciliated: cauline lvs. numerous, slightly separated, oval-lanceolate, brown toward their tip and tufted ciliate: fl.-st. weak, almost prostrate on the ground during flowering and glandular-hairy; petals oval-lanceolate, acuminate. Switzerland. Not treated in any of the recent Swiss floras but offered in the trade.—S. hispanicum, Willd., is a doubtful species with subulate, semi-terete, ciliate, imbricated lvs.; possibly a Sedum.—S. hispanicum, Pourr., equals Sedum nicaeense.—S. hispidulum, Hort., is offered in the trade.—S. hispidum, Hort., is a horticultural name.—S. humilum, Hort., is a horticultural name.—S. kopaonikense. Panc., is said to be related to S. Heuffelii by Pancic, but is not well known and it is suggested that it is only a form of that species by recent authors. Serbia.—S. Laggei, Hort., is presumably an error for Laggeri.—S. leucanthemum, Hort., is probably an error for leucanthum.—S. leucanthum, Panc., is described as a form with rather small rosettes, 12-merous fls. and white petals, grown in gardens, now questionably referred to S. tectorum.-S. marginatum, Hort., is offered in the trade.—S. pilosum, Hort., is a trade name.—S. pyrenaicum, Lamotte, is offered in the trade as having handsomely formed and dark red rosettes. Eu. The botanical description is not available and the recent European floras do not treat this species.—S. rubens, Hort., is offered in the trade.—S. rubrum, Hort., is offered as having a dark base to the lvs., possibly the same as S. tectorum var. rubrum.—N. rupestre, Hort., is a trade name, perhaps a form of S. tectorum.—S. Scherzerianum, Hort., is offered in the trade.—S. speciosum, Lamotte, is offered in the trade. Eu. The botanical description is not available and none of the recent European floras mentions it.—.S. spinosum, Hort., is a trade name.—S. spinulifolium, Hort., is offered in the trade and also occurs in botanic gardens.—S. Thomsonii, Lindsay (S. arachnoideum X S. tectorum), is offered in the trade; no description of the hybrid is available.—S. umbicilum, Hort., is a trade name. Var. spinosum, Hort., is a trade name perhaps the same as the plant offered in the trade as S. spinosum.—S. urbicum, C. Smith. Shrubby: st. erect, 3 ft. high, simple, stout, covered with lf.-scars: lvs. many, rosulate at the top of the st., 4-6 x 1 1/2 in., narrowly spatulate, cuspidate, very thick, pale green, margins erosely serrulate, sessile or short-petioled: panicle very large, pyramidal, 3 ft. high and nearly as broad, many-branched; fls. 10-merous, pale yellow, 3/4 in. across; calyx cup-shaped; petals lanceolate, acute. Canary Isls. B.M. 7893. Belongs to the same group as S. arboreum. A very showy species but tender.—S. violaceum, Hort., is offered in the trade; possibly the same as S. tectorum var. violaceum.—S. Zelebori, Schott. Barren rosette more than 2 in. diam., the young ones borne on densely puberulent peduncles: lvs. spatulate-oblanceolate to spatulate-lingulate, apex apiculate and purple, short-ciliate, both surfaces densely puberulent, glaucous; cauline lvs. smaller, linear-lingulate, apiculate and puberulent: fl.-st. minutely glandular and densely hirsute: fls. 11-12-merous, pale yellowish: calyx-segms. lanceolate: petals linear-lanceolate, acuminate, viscid hirtellous dorsally. Serbia. By some authorities referred to S. Pittonii, by others to S. globiferum; apparently distinct from both of them.
 
 
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==Cultivation==
 
==Cultivation==
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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.
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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.
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===Propagation===
 
===Propagation===
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===Pests and diseases===
 
===Pests and diseases===
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==Species==
 
==Species==
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<!-- This section should be renamed Cultivars if it appears on a page for a species (rather than genus), or perhaps Varieties if there is a mix of cultivars, species, hybrids, etc    -->
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[[Image:CommonHouseleek.jpg|thumb|200px| ''[[Sempervivum tectorum]]'' (Common Houseleek)]]
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[[Image:Sempervivum arachnoideum.jpg|thumb|200px|''Sempervivum arachnoideum''.]]
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[[Image:Sempervivum tectorum.JPG|thumb|250px|''[[Sempervivum tectorum]]'']]
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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 (genetics)|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]], [[variety (biology)|varieties]], and [[form (botany)|form]]s were described, without well-defined limits between them. As a second consequence, there are a high frequency of natural [[Hybrid (biology)|hybrids]] in this genus and the possibility of [[back-crossing]]s of these. However, more or less 40 species can be individualized in the whole area of the genus, but there are many more local [[population]]s, without nomenclatural valour but with sometimes their own characters.
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Species include:
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*Sempervivum affine, Lamotte, is offered in the trade as having dark green rosettes marked with rose: fls. red. Eu. The botanical description is not available and the species is not treated in recent European floras.{{SCH}}
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*''[[Sempervivum albidum]]''
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*''[[Sempervivum altum]]''
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*''[[Sempervivum arachnoideum]]''
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*''[[Sempervivum arboreum]]''
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*''[[Sempervivum arenarium]]''
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*''[[Sempervivum armenum]]''
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*''[[Sempervivum atlanticum]]''
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*Sempervivum atropurpureum, Hort., is offered in the trade as having rosettes washed with purple: fls. red.{{SCH}}
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*''[[Sempervivum ballsii]]''
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*''[[Sempervivum borissovae]]''
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*''[[Sempervivum calcareum]]''
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*''[[Sempervivum canariense]]''
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*''[[Sempervivum cantabricum]]''
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*''[[Sempervivum caucasicum]]''
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*Sempervivum chrysanthoides, Hort., is offered in the trade as a form with white fls.{{SCH}}
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*''[[Sempervivum chrysanthum]]''
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*''[[Sempervivum ciliosum]]'', Barren rosettes more or less flat, up to 1 1/4 in. diam.: lvs. oblong-lanceolate, more or less acuminate, up to 3/4 in. long, keeled beneath, conspicuously long white-ciliate toward the apex, pubescent above, outer lvs. red-tinted; cauline lvs. imbricate, tip red-suffused: fl.- sts. about 2 in. high, bearing about 6 subsessile fls.: fls. about 1 in. across, pale green, 9-11-merous; calyx-segms. oblong-lanceolate, acute, glandular-pubescent; petals linear, glandular-pubescent externally. Hab.(?). Grown in botanic gardens.{{SCH}}
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*Sempervivum colchicum, Hort., is offered in the trade.{{SCH}}
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*Sempervivum commutatum, Hort., is offered in the trade.{{SCH}}
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*''[[Sempervivum davisii]]''
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*Sempervivum Delpontii, Hort., is a trade name.{{SCH}}
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*''[[Sempervivum dolomiticum]]''
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*Sempervivum elegans, Lagg. Rosettes small, about 1/2 in. diam., the young ones on short shoots forming a mat: lvs. linear-lanceolate, cuspidate, short-villous, weakly cobwebbed, pale green, slightly ciliated: cauline lvs. numerous, slightly separated, oval-lanceolate, brown toward their tip and tufted ciliate: fl.-st. weak, almost prostrate on the ground during flowering and glandular-hairy; petals oval-lanceolate, acuminate. Switzerland. Not treated in any of the recent Swiss floras but offered in the trade.{{SCH}}
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*''[[Sempervivum erythraeum]]''
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*''[[Sempervivum glabrifolium]]''
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*''[[Sempervivum hausmannii]]''
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*''[[Sempervivum heterotrichum]]''
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*''[[Sempervivum heuffelii]]''
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*''[[Sempervivum hirtum]]''
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*Sempervivum hispanicum, Willd., is a doubtful species with subulate, semi-terete, ciliate, imbricated lvs.; possibly a Sedum.{{SCH}}
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*Sempervivum hispanicum, Pourr., equals Sedum nicaeense{{SCH}}
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*Sempervivum hispidulum, Hort., is offered in the trade.{{SCH}}
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*Sempervivum hispidum, Hort., is a horticultural name.{{SCH}}
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*Sempervivum humilum, Hort., is a horticultural name.{{SCH}}
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*''[[Sempervivum ingwersenii]]''
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*''[[Sempervivum juvanii]]''
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*''[[Sempervivum kindingeri]]''
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*Sempervivum kopaonikense. Panc., is said to be related to Sempervivum Heuffelii by Pancic, but is not well known and it is suggested that it is only a form of that species by recent authors. Serbia.{{SCH}}
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*''[[Sempervivum kosaninii]]''
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*Sempervivum Laggei, Hort., is presumably an error for Laggeri.{{SCH}}
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*''[[Sempervivum laggeri]]''
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*Sempervivum leucanthemum, Hort., is probably an error for leucanthum.{{SCH}}
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*''[[Sempervivum leucanthum]]'', is described as a form with rather small rosettes, 12-merous fls. and white petals, grown in gardens, now questionably referred to Sempervivum tectorum.{{SCH}}
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*''[[Sempervivum macedonicum]]''
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*Sempervivum marginatum, Hort., is offered in the trade.{{SCH}}
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*''[[Sempervivum marmoreum]]''
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*''[[Sempervivum minus]]''
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*''[[Sempervivum montanum]]''
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*''[[Sempervivum nevadense]]''
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*''[[Sempervivum octopodes]]''
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*''[[Sempervivum ossetiense]]''
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*Sempervivum pilosum, Hort., is a trade name.{{SCH}}
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*''[[Sempervivum pittonii]]''
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*''[[Sempervivum poculiforme]]''
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*''[[Sempervivum pumilum]]''
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*Sempervivum pyrenaicum, Lamotte, is offered in the trade as having handsomely formed and dark red rosettes. Eu. The botanical description is not available and the recent European floras do not treat this species.{{SCH}}
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*''[[Sempervivum reginae-amaliae]]''
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*Sempervivum rubens, Hort., is offered in the trade.{{SCH}}
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*Sempervivum rubrum, Hort., is offered as having a dark base to the lvs., possibly the same as Sempervivum tectorum var. rubrum.{{SCH}}
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*Sempervivum rupestre, Hort., is a trade name, perhaps a form of Sempervivum tectorum.{{SCH}}
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*''[[Sempervivum rupicolum]]''
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*Sempervivum Scherzerianum, Hort., is offered in the trade.{{SCH}}
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*''[[Sempervivum soboliferum]]''
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*''[[Sempervivum sosnowskyi]]''
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*''[[Sempervivum spathulatum]]''
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*Sempervivum speciosum, Lamotte, is offered in the trade. Eu. The botanical description is not available and none of the recent European floras mentions it.{{SCH}}
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*Sempervivum spinosum, Hort., is a trade name.{{SCH}}
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*Sempervivum spinulifolium, Hort., is offered in the trade and also occurs in botanic gardens.{{SCH}}
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*''[[Sempervivum tabulaeforme]]''
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*''[[Sempervivum tectorum]]''
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*Sempervivum Thomsonii, Lindsay (Sempervivum arachnoideum X Sempervivum tectorum), is offered in the trade; no description of the hybrid is available.{{SCH}}
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*Sempervivum umbicilum, Hort., is a trade name. Var. spinosum, Hort., is a trade name perhaps the same as the plant offered in the trade as Sempervivum spinosum.{{SCH}}
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*Sempervivum urbicum, C. Smith. Shrubby: st. erect, 3 ft. high, simple, stout, covered with lf.-scars: lvs. many, rosulate at the top of the st., 4-6 x 1 1/2 in., narrowly spatulate, cuspidate, very thick, pale green, margins erosely serrulate, sessile or short-petioled: panicle very large, pyramidal, 3 ft. high and nearly as broad, many-branched; fls. 10-merous, pale yellow, 3/4 in. across; calyx cup-shaped; petals lanceolate, acute. Canary Isls. B.M. 7893. Belongs to the same group as Sempervivum arboreum. A very showy species but tender.{{SCH}}
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*''[[Sempervivum thompsonianum]]''
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*''[[Sempervivum transcaucasicum]]''
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*Sempervivum violaceum, Hort., is offered in the trade; possibly the same as Sempervivum tectorum var. violaceum.{{SCH}}
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*''[[Sempervivum wulfenii]]''
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*''[[Sempervivum zeleborii]]''
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*Sempervivum Zelebori, Schott. Barren rosette more than 2 in. diam., the young ones borne on densely puberulent peduncles: lvs. spatulate-oblanceolate to spatulate-lingulate, apex apiculate and purple, short-ciliate, both surfaces densely puberulent, glaucous; cauline lvs. smaller, linear-lingulate, apiculate and puberulent: fl.-st. minutely glandular and densely hirsute: fls. 11-12-merous, pale yellowish: calyx-segms. lanceolate: petals linear-lanceolate, acuminate, viscid hirtellous dorsally. Serbia. By some authorities referred to Sempervivum Pittonii, by others to Sempervivum globiferum; apparently distinct from both of them.{{SCH}}
  
 
==Gallery==
 
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==References==
 
==References==
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*[[Standard Cyclopedia of Horticulture]], by L. H. Bailey, MacMillan Co., 1963
 
*[[Standard Cyclopedia of Horticulture]], by L. H. Bailey, MacMillan Co., 1963
 
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Latest revision as of 20:08, 25 May 2010


Hen & Chicks (Sempervivum tectorum)


Plant Characteristics
Habit   cacti-succulent

Lifespan: ⌛ perennial
Cultivation
Exposure: ☼ part-sun
Water: ◍ moderate, dry
Scientific Names

Crassulaceae >

Sempervivum >


Houseleeks or Liveforever (Sempervivum, pronounced /sɛmpəˈvaɪvəm/)[1] 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.

They occur in N Africa and S Europe to Iran. 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.

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.

"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.


Read about Sempervivum in the Standard Cyclopedia of Horticulture 

Sempervivum (Latin, living forever). Crassulaceae. Houseleek. Thick fleshy usually stemless, perennial herbs or subshrubs which are used for carpet-bedding, rockeries, and the like. See Succulents for culture.

Leaves alternate, thick-fleshy, often revolute: cymes panicled, usually densely: fls. white, rose, green, yellow, or purple; calyx 6- to many-cleft or -parted, rarely 5- cleft; petals 6 to many, free or connate at the base, oblong or lanceolate; stamens double as many as the petals, rarely the same number, free; ovary with as many carpels as petals, free or the base or up to the middle immersed in the calyx-tube: fr. many-seeded follicles.—About 65 species, widely scattered in the mountains of the Old World. The genus was monographed (horticulturally) by J. G. Baker in Gardener's Chronicle for 1879, and his treatment has been followed here to some extent with the addition of several species and slight modifications to meet more recent knowledge of the genus. Sempervivum is closely related to Sedum, but the floral parts are multiples of 6 or some larger number, while the floral parts of Sedum are in 5's. The genus is a difficult one for the botanist, and the specific limits are very uncertain and unsatisfactory, no two authors agreeing. The key given will undoubtedly prove faulty, but is an attempt to simplify the determination of the species.

Sempervivums are mostly hardy perennials and stemless, and increase by rosettes (Fig. 3602) which are sent out from the parent plant, thereby suggesting the popular name "hen-and-chickens." The leaves are thick, short, and succulent. The flowers, which are borne in panicled cymes, are mostly yellow, greenish yellow, or some shade of rose or purple, rarely white. The individual flowers are larger than those of sedum, but the clusters are less showy. Houseleeks are cultivated more for foliage than for flowers. They are not used for as great a variety of purposes as sedums, but they are popular for carpet-bedding, rockwork, and covering dry banks and bare sandy wastes. They are of the easiest culture and are quickly multiplied by means of the offsets or rosettes. They may be used alone for permanent carpet-beds, and for this special purpose are preferable to the more popular but tender echeveria. The foliage remains green all winter. The leaves are often spotted with red toward the tip, and this color is brighter if the plants have full sunlight. The names "houseleek" and "hen-and-chickens" are loosely applied to the whole genus. If these names are to be restricted, the former should be used for Sempervivum tectorum and the latter for S. soboliferum. The common species, which grows on the roofs of houses in Europe, is S. tectorum. In the case of S. soboliferum the young rosettes are attached to the parent plant by a more slender thread than usual and more easily detach themselves and roll about. The spider-web species, of which S. arachnoideum is the commonest, are the prettiest, of them all, by reason of the webs that cover the young rosettes. These coverings are made by the plants themselves and are incidental to development, but in some species are not strongly developed and in all the group are less noticeable in the old rosettes. CH


The above text is from the Standard Cyclopedia of Horticulture. It may be out of date, but still contains valuable and interesting information which can be incorporated into the remainder of the article. Click on "Collapse" in the header to hide this text.


Cultivation

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.


Propagation

Pests and diseases

Species

Sempervivum tectorum (Common Houseleek)
Sempervivum arachnoideum.
Sempervivum tectorum

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.

Species include:

  • Sempervivum affine, Lamotte, is offered in the trade as having dark green rosettes marked with rose: fls. red. Eu. The botanical description is not available and the species is not treated in recent European floras.CH
  • Sempervivum albidum
  • Sempervivum altum
  • Sempervivum arachnoideum
  • Sempervivum arboreum
  • Sempervivum arenarium
  • Sempervivum armenum
  • Sempervivum atlanticum
  • Sempervivum atropurpureum, Hort., is offered in the trade as having rosettes washed with purple: fls. red.CH
  • Sempervivum ballsii
  • Sempervivum borissovae
  • Sempervivum calcareum
  • Sempervivum canariense
  • Sempervivum cantabricum
  • Sempervivum caucasicum
  • Sempervivum chrysanthoides, Hort., is offered in the trade as a form with white fls.CH
  • Sempervivum chrysanthum
  • Sempervivum ciliosum, Barren rosettes more or less flat, up to 1 1/4 in. diam.: lvs. oblong-lanceolate, more or less acuminate, up to 3/4 in. long, keeled beneath, conspicuously long white-ciliate toward the apex, pubescent above, outer lvs. red-tinted; cauline lvs. imbricate, tip red-suffused: fl.- sts. about 2 in. high, bearing about 6 subsessile fls.: fls. about 1 in. across, pale green, 9-11-merous; calyx-segms. oblong-lanceolate, acute, glandular-pubescent; petals linear, glandular-pubescent externally. Hab.(?). Grown in botanic gardens.CH
  • Sempervivum colchicum, Hort., is offered in the trade.CH
  • Sempervivum commutatum, Hort., is offered in the trade.CH
  • Sempervivum davisii
  • Sempervivum Delpontii, Hort., is a trade name.CH
  • Sempervivum dolomiticum
  • Sempervivum elegans, Lagg. Rosettes small, about 1/2 in. diam., the young ones on short shoots forming a mat: lvs. linear-lanceolate, cuspidate, short-villous, weakly cobwebbed, pale green, slightly ciliated: cauline lvs. numerous, slightly separated, oval-lanceolate, brown toward their tip and tufted ciliate: fl.-st. weak, almost prostrate on the ground during flowering and glandular-hairy; petals oval-lanceolate, acuminate. Switzerland. Not treated in any of the recent Swiss floras but offered in the trade.CH
  • Sempervivum erythraeum
  • Sempervivum glabrifolium
  • Sempervivum hausmannii
  • Sempervivum heterotrichum
  • Sempervivum heuffelii
  • Sempervivum hirtum
  • Sempervivum hispanicum, Willd., is a doubtful species with subulate, semi-terete, ciliate, imbricated lvs.; possibly a Sedum.CH
  • Sempervivum hispanicum, Pourr., equals Sedum nicaeenseCH
  • Sempervivum hispidulum, Hort., is offered in the trade.CH
  • Sempervivum hispidum, Hort., is a horticultural name.CH
  • Sempervivum humilum, Hort., is a horticultural name.CH
  • Sempervivum ingwersenii
  • Sempervivum juvanii
  • Sempervivum kindingeri
  • Sempervivum kopaonikense. Panc., is said to be related to Sempervivum Heuffelii by Pancic, but is not well known and it is suggested that it is only a form of that species by recent authors. Serbia.CH
  • Sempervivum kosaninii
  • Sempervivum Laggei, Hort., is presumably an error for Laggeri.CH
  • Sempervivum laggeri
  • Sempervivum leucanthemum, Hort., is probably an error for leucanthum.CH
  • Sempervivum leucanthum, is described as a form with rather small rosettes, 12-merous fls. and white petals, grown in gardens, now questionably referred to Sempervivum tectorum.CH
  • Sempervivum macedonicum
  • Sempervivum marginatum, Hort., is offered in the trade.CH
  • Sempervivum marmoreum
  • Sempervivum minus
  • Sempervivum montanum
  • Sempervivum nevadense
  • Sempervivum octopodes
  • Sempervivum ossetiense
  • Sempervivum pilosum, Hort., is a trade name.CH
  • Sempervivum pittonii
  • Sempervivum poculiforme
  • Sempervivum pumilum
  • Sempervivum pyrenaicum, Lamotte, is offered in the trade as having handsomely formed and dark red rosettes. Eu. The botanical description is not available and the recent European floras do not treat this species.CH
  • Sempervivum reginae-amaliae
  • Sempervivum rubens, Hort., is offered in the trade.CH
  • Sempervivum rubrum, Hort., is offered as having a dark base to the lvs., possibly the same as Sempervivum tectorum var. rubrum.CH
  • Sempervivum rupestre, Hort., is a trade name, perhaps a form of Sempervivum tectorum.CH
  • Sempervivum rupicolum
  • Sempervivum Scherzerianum, Hort., is offered in the trade.CH
  • Sempervivum soboliferum
  • Sempervivum sosnowskyi
  • Sempervivum spathulatum
  • Sempervivum speciosum, Lamotte, is offered in the trade. Eu. The botanical description is not available and none of the recent European floras mentions it.CH
  • Sempervivum spinosum, Hort., is a trade name.CH
  • Sempervivum spinulifolium, Hort., is offered in the trade and also occurs in botanic gardens.CH
  • Sempervivum tabulaeforme
  • Sempervivum tectorum
  • Sempervivum Thomsonii, Lindsay (Sempervivum arachnoideum X Sempervivum tectorum), is offered in the trade; no description of the hybrid is available.CH
  • Sempervivum umbicilum, Hort., is a trade name. Var. spinosum, Hort., is a trade name perhaps the same as the plant offered in the trade as Sempervivum spinosum.CH
  • Sempervivum urbicum, C. Smith. Shrubby: st. erect, 3 ft. high, simple, stout, covered with lf.-scars: lvs. many, rosulate at the top of the st., 4-6 x 1 1/2 in., narrowly spatulate, cuspidate, very thick, pale green, margins erosely serrulate, sessile or short-petioled: panicle very large, pyramidal, 3 ft. high and nearly as broad, many-branched; fls. 10-merous, pale yellow, 3/4 in. across; calyx cup-shaped; petals lanceolate, acute. Canary Isls. B.M. 7893. Belongs to the same group as Sempervivum arboreum. A very showy species but tender.CH
  • Sempervivum thompsonianum
  • Sempervivum transcaucasicum
  • Sempervivum violaceum, Hort., is offered in the trade; possibly the same as Sempervivum tectorum var. violaceum.CH
  • Sempervivum wulfenii
  • Sempervivum zeleborii
  • Sempervivum Zelebori, Schott. Barren rosette more than 2 in. diam., the young ones borne on densely puberulent peduncles: lvs. spatulate-oblanceolate to spatulate-lingulate, apex apiculate and purple, short-ciliate, both surfaces densely puberulent, glaucous; cauline lvs. smaller, linear-lingulate, apiculate and puberulent: fl.-st. minutely glandular and densely hirsute: fls. 11-12-merous, pale yellowish: calyx-segms. lanceolate: petals linear-lanceolate, acuminate, viscid hirtellous dorsally. Serbia. By some authorities referred to Sempervivum Pittonii, by others to Sempervivum globiferum; apparently distinct from both of them.CH

Gallery

  • photo 1

  • photo 2

  • photo 3

References

  1. ↑ Oxford English Dictionary, 2nd Edition 1989

External links


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