SEMELE 



SEMPERVIVUM 



3143 



Gn. 72, p. 432. G.M. 31 'ATI, 479; 37:261. The mem- 

 bers which have the position of Ivs. are minute scales, 

 in the axil of which are borne the cladophylla, the 

 latter being 3-4 in. long. It is grown in the open in S. 

 Calif, and is said to look like a gigantic smilax and to 

 have dark green, tropical foliage likely to be mistaken 

 for some of the Indian climbing palms. 



F. TRACY HuBBARD.f 



SEMIBEGONIELLA is a recent genus of the Begoni- 

 aceae, differing from Begonia in having a tubular male 

 flower (Symbegonia has a tubular female flower), appar- 

 ently not in cult. S. Sodiroi, C. DC., from Ecuador 

 was "described, and the genus founded, in 1908. 



SEMPERVIVUM (Latin, living forever). Crassur 

 lacese. 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 mono- 

 graphed (horticulturally) by J. G. Baker in Gardener's 

 Chronicle for 1879, and his treatment has been fol- 

 lowed 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 o's. The genus is a difficult one for the botanist, 

 and the specific limits are very uncertain and unsatis- 

 factory, 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 culti- 

 vated 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 carpets-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 ap- 

 plied 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 them- 

 selves and roll about. The spider-web species, of 

 which S. arachnoideum is the commonest, are the pret- 

 tiest 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. 



KEY TO THE SPECIES. 



A. Plants without secondary rosettes on 



offshoots: fls. usually yellow. 

 B. St. herbaceous, with the basal Ivs. in a 



rosette 1. poculifonne 



BB. St. shrubby, with the hs. in a rosette 

 at the end of the branches. 



c. Surface of hs. vittous 2. canariense 



cc. Surface of Its. glabrous. 



D. Lrs. obovate-spatulate or round- 

 ish ovate. 

 E. Petals elliptical; calyx-seams. 



ovate 3. arboreum 



EE. Petals linear-lanceolate; calyx- 



segms. short-triangular .... 4. chrysanthum 

 DD. Lrs. oblong-spatulate. 



E. Margin of Irs. ciliate 5. tabulaefonne 



EE. Margin of Ivs. papillose 6. spathulatum 



AA. Plants rcith secondary rosettes on offsets 



or sessile. 



B. Fls. usually 6-merous; not wide- 

 spreading at maturity, 

 c. The fls. small; petals not fimbriated 



on the margin and keel. 

 D. Segms. of calyx linear-oblong; 



petals linear-oblong 7. Heuffelii 



DD. Segms. of calyx lanceolate; petals 



Ungulate 8. Reginse- 



cc. The fls. large; petals fimbriated on [Amalise 



the margin and keel. 

 D. New rosettes rotted up into 

 round balls. 



E. Lrs. obovate-cuneate 9. soboliferum 



EE. Lrs. oblanceolate 10. arenarium 



DD. New rosettes not rolled up into 



round balls 11. hirtum 



BB. Fls. usually 12-merous (9-lJ^ner- 

 ous); widely expanded at maturity. 

 c. Color of fls. yellow or yellowish. 

 D. Surface of hs. glabrous. 



E. The hs. obotate-cuneate 12. Wulfenii 



EE. The hs ovate-lanceolate. .... 13. albidum 

 DD. Surface of Ivs. more or less hairy. 

 E. Blade of If. ensiform, Ungu- 

 late, or oblanceolate 14. Pittonii 



EE. Blade of If. more or less obo- 

 vate-cuneate. 



F. Segms. of calyx oblong. ... 15. rupicolum 

 FF. Segms. of calyx lanceolate. 

 G. Petals linear-lanceolate, 

 acute, green-striate ex- 

 ternally 16. globiferum 



GG. Petals lanceolate, acu- 

 minate, not green-stri- 

 ate externally 17. grandiflorum 



cc. Color of fls. reddish or purplish. 

 D. Inner hs. of rosette with their 

 tips connected by fine hairs like 

 a spider's web. (The follow- 

 ing 5 species are very closely 

 related.) 



