Caryophyllaceæ. 



239 



in habit as the present species. Many travellers have there- 

 fore described and illustrated these fresh-green, flatly-arched 

 cushions, which during the flowering-period are covered 

 with pink stars of 5 rays. Figures are found for instance 

 in Bonnier, Lazniewski, Kerner (Pflanzenleben, PI. 193), 

 Börgesen (Botany of the Færoes), and in Feilden (Geog. 

 Soc, April, 1898), C. Kruuse (1911, p. -358, Fig. 4) and others. 



The shoots with their numerous old leaves, are usually 

 so densely crowded in the cushions, that they form a spongy 

 mass, which by its capillarity can absorb a great quantity 

 of water. It is therefore very natural that adventitious 

 roots are developed in their in- 

 terior, which must to a certain 

 degree take their nourishment 

 from the old fragments of the 

 plant's own leaves. But mention 

 is also made of tolerably loose 

 and divergently branched tufts, 

 which may, for instance, have 

 stems as long as 20 cm. ; this is 

 due to the nature of the station; 

 as e. g. when the plant grows 

 among damp moss, or in a parti- 

 cularly shady, damp locality. 



Tufts, eroded by the wind, are described and figured 

 by Hartz and Kruuse. Kruuse (1912, Fig. 4], p. 270) 

 writes : 'The tufts reach a diameter of 30 — 40 cm and a 

 height of 7 — 10 cm, but the windward is often eroded and 

 dead." Kihlmann also records such tufts from Kola. 



Vegetative propagation under natural conditions is 

 not known to me, but as gardeners are able to divide the 

 tufts, adventitious roots must be so vigorously developed, 

 that propagation by layers can take place. 



IG* 



Fig. 4. Silène acaulis. 

 A small portion of [a tuft; 

 about Vi- On some of the shoots 

 the green leaves are seen, sur- 

 rounded by dead leaves. (From 

 Iceland; Helgi Jonsson; 31. 12. 

 1893.) 



