Caryophyllaceæ. 237 



"numerous, short, sterile, leaf-bearing shoots," besides the 

 "ascending or erect . . . stems." I have observed similar fea- 

 tures in Viscaria purpurea (in Norway near Finse and in Den- 

 mark), and in Viscaria alpina there even appears to be an 

 attempt towards the formation of scale-leaves on such 

 shoots. In Denmark Lychnis flos cuculi, Silène nutans and 

 Melandrium dioecum have similar shoots. 



Pulvinate habit. Pulvinate forms develop easily from 

 the typically cæspitose forms when the external conditions 

 are unfavourable. When cold or strong wind checks the 

 growth, the shoots become short and very much crowded, 

 the entire mesocorm becomes very compact and closely set 

 with branches, more or less semi-globular, and the flower- 

 bearing portions of the shoots protrude only slightly above 

 the surface of it. The pulvinate form is only a modification; 

 to the same species may belong individuals with a divergently 

 branched and long-branched mesocorm, and also dwarf-in- 

 dividuals with a pulvinate habit. The pulvinate form occurs 

 at any rate in Melandrium affine and apetalum. 



Adventitious Buds. On the naked vertical axis 



below the leaf-bearing mesocorm of old plants, small buds 



are sometimes seen, the origin of which may be doubtful 



(Fig. 2, g). Perhaps they are adventitious buds on the primary 



root, but it is more probable that they are axillary buds 



from former foliage-leaves on the main axis which buds have 



not had favourable conditions for their development. I have 



Been such buds in Melandrium apetalum^ M. affine and M. 



triflorum. 



B. The Silène acaulis type. 



To this I refer only this one species, which is decidedly 

 cæspitose in habit, and has a tap-root growing far down into 

 the ground, but differs from the Melandrium-iype in not 

 having semi-rosette shoots, but long-shoots with short inter- 



XXXVII. ^ 



