Sempervivum L. Sempervivum Sempervivum, Hoppe ex Mert. & Koch

6. Sempervivum L. View in CoL 2

Perennials with monocarpic rosettes; vegetative reproduction by axillary stolons. Leaves alternate, entire, sessile, ciliate, very fleshy. Hairs, if present, glandular. Flowers 8- to 16-merous, in a terminal cyme. Sepals lanceolate, pubescent. Petals yellowish, pink or purple, patent, narrow-lanceolate, entire, pubescent on margins and lower surface. Stamens twice as many as petals; filaments usually pubescent at least at the base. Carpels equal in number to the petals; ovary pubescent; style distinct, outwardly curved. Seeds pyriform, finely striate. The habitat of all species, unless otherwise indicated, is in rocky places, mainly in the mountains. Hybrids in this genus are very common both in natural habitats and in cultivation. The most widespread are S. x barbulatum Schott (10 x 11), S. x fauconnettii Reuter (10 x 22), and S. x schottii C. B. Lehm. & Schnittspahn (11 x 22). The hybrids usually occur only in the presence of both parents, but in the French Jura, the locus classicus of S. x fauconnettii, one of the parents (10) is not now present.

Literature: R. L. Praeger: An Account o f the Sempervivum

Group. London. 1932. 1 Upper surface of petals yellowish, at least in the apical half 2 Leaves glaucous, glabrous except for marginal cilia 1. wulfenii 2 Leaves not glaucous, with glandular-pubescent surface 3 Plant with resinous odour 4 Filaments purple 2. grandiflorum 4 Filaments pale yellow or whitish It. montanum 3 Plant without distinctive odour 5 Cilia of rosette-leaves 2-4 mm, stiff, interwoven with those of neighbouring leaves 3. ciliosum 5 Cilia less than 2 mm, not interwoven 6 Petals tinged with pink or purple towards the base; filaments ± purple

7 Flowering stem 10 cm or less

8 Petals with white margin; otherwise mainly pink, but yellow towards the apex 4. thompsonianum

8 Petals without white margin; mainly yellow, but with a lilac spot near the base 5. octopodes

7 Flowering stem 12-25 cm

9 Petals bright greenish-yellow; filaments entirely purple

6. zeleborii

9 Petals pale yellow or cream-coloured; filaments pale yellow, striped with red 7. kindingeri 6 Petals not tinged with purple or pink; filaments usually pale

10 Stolons 5-8 cm 8. leucanthum

10 Stolons 2-3 cm 9. pittonii 1 Upper surface of petals predominantly red, pink or purple 11 Mature leaves pubescent on both surfaces 12 Apical cilia of leaves very long and flexuous, interwoven to form an arachnoid tomentum over the rosette

10. arachnoideum 12Apical cilia short, not arachnoid 13 Plant with resinous odour; cilia of rosette-leaves scarcely longer than the other hairs; petals 12-20 mm 11. montanum 13 Plant without distinctive odour; cilia of rosette-leaves at least twice as long as the other hairs; petals 7-11 mm 14 Rosette-leaves sparsely pubescent

15 Stem usually more than 20 cm, bearing at least 40 flowers

23. tectorum

15 Stem 8-16 cm, bearing 12-30 flowers

16 Rosette-leaves 10-15 mm, acuminate, bright green;

flowers deep pink 12. dolomiticum

16 Rosette-leaves c.35 mm, mucronate, dark green; flowers dark reddish-purple 13. cantabricum 14 Rosette-leaves densely pubescent

17 Petals almost entirely pink or red (sometimes with a very narrow white border)

18 Stolons 4-12 cm; rosettes well-spaced

19 Rosettes 6-8 cm in diameter; stolons stout 14. kosaninii

19 Rosettes 3-5 cm in diameter; stolons slender

15. macedonicum

18 Stolons c. 2 cm; rosettes crowded

20 Leaves velvety with soft, short hairs; cilia straight;

flowering stem 15-20 cm, stout 16. erythraeum

20 Hairs on leaves rather stiff; cilia sharply bent;

flowering stem c. 12 cm, slender 17. giuseppii 17 Petals with a conspicuous white margin, or greenish beneath

21 Petals dark crimson on both surfaces, with a white margin (vide 19). reginae-amaliae

21 Petals chiefly pale pink, but yellowish at apex and greenish beneath 4. thompsonianum 11 Mature leaves glabrous apart from marginal cilia (or rarely puberulent) 22 Young leaves puberulent on both surfaces 23 Mature leaves not cibate in apical third 18. ballsii 23 Mature leaves cibate to the apex 24 Rosettes c. 3 cm in diameter (S. Spain) 20. nevadense 24 Rosettes c. 6 cm in diameter (C. & S.E. Europe)

19. marmoreum 22 Young leaves glabrous except for marginal cilia 25 Stem c. 12 cm, bearing less than 30 flowers 26 Inner leaves of rosette connivent, forming a cone; anthers yellow 21. andreanum 26 Inner leaves of rosette erect; anthers reddish-brown

20. nevadense 25 Stem usually more than 20 cm, bearing more than 30

flowers 27 Rosettes flattened or concave; leaves with a well-defined,

reddish-brown spot near the apex 23. calcareum 27 Rosettes not flattened or concave; leaves variably suffused with red towards the apex, but without a well-defined spot 22. tectorum

1. S. wulfenii Hoppe ex Mert. & Koch View in CoL in Rohling, Deutschl. FI. ed. 3,3:386(1831).

Stolons long, stout, woody. Rosettes 4-5 cm in diameter; inner leaves connivent. Leaves c. 30 x 12 mm, oblongspathulate, cuspidate, glabrous except for cilia, glaucous; margins somewhat revolute towards the apex. Flowering stem 15-25 cm. Flowers 11- to 15-merous; petals 10 x 1-2 mm, lemon-yellow with a basal purple spot; filaments purple. 2/2=36. 1700-2700 m; usually calcifuge. • E. Alps, extending locally to C. Alps. Au He It.