Caryophyllaceæ. 



245 



cushions. In the same species the branch-systems may either 

 be long and divergently placed, with flowers raised high above 

 the ground, or they may be so short and crowded together 

 that dense semi-globular or globular cushions are formed 

 with flowers, lying almost upon the surface of the cushion, 

 or resting upon it. In Fig. 6 three specimens are shown 

 which belong to the form-cycle of Minuartia verna, and 



Fig. 6. Minuartia verna (reduced). 



A, var. hirta. W. Greenland, 74°18' N. lat. (C. Ryder). B, var. kirta. 



Scoresby Sound (N. Hartz). C, var. rubella. Spitzbergen (Hanna 



Resvoll Holmsen). 



which show all these modifications within the same species. 

 It is evident that the forms are dependent on the life-con- 

 ditions prevailing in the stations. 



A pulvinate habit has been found to occur in Minu- 

 artia verna (Fig. 6), M. biflora, M. Rossii (Fig. 7), Sagina 

 Linnæi, S. cæspitosa, S. intermedia and S. procumbens (as 

 also in S. subulata). See figures in Simmons, PI. 6, pp. 4 — 6 

 and in Ostenfeld and Lundager, p. 19. In his excellent 



