266 



The other differences are not characteristic enough to be 

 given as a key; they are best seen in the figures. 



Saxifraga aizoides L. (Figs. 16, 17 and 181. 

 Saxifraga aizoides L. according to Norman is a decided 

 mountain-plant which grows both upon very wet and very dry 



ground, and occurs 

 most commonly on 

 the sunny side. 



The leaf is linear, 

 thick and succulent 

 and terminates in a 

 point at the base of 

 which is found the 

 only hydathode of 

 the leaf. A few hairs 

 occur along the 

 margin towards the 

 base; the leaf is 

 otherwise glabrous. 

 The epidermis of 

 the upper surface 

 (Figs.l65; island 

 C) consists of cells 

 with slightly undula- 

 ting, lateral walls and 

 well-developed outer 

 walls with distinct 

 cuticle. At the base of the leaf, the lateral walls of the cells 

 are straight and the cells are long and narrow. Stomata are 

 absent at the base of the leaf upon its middle part, but in 

 other places are evenly distributed. The stomata are parallel 

 with the longitudinal axis of the leaf; they are placed on a 

 level with the leaf-surface. 



Fig. 16. Saxifraga aizoides. 



The leaf: A (-/i), Leaf-form. B, Upper epidermis. C, Lower 



epidermis: the middle line of the leaf is to the right. 0, 



Marginal hair. (B, C, D ■«!{). 



