44 HYDROCHARITACEAE [ch. 



interpreted as paired axillary stipules, whose leaf-blade is 

 generally rudimentary^. They are succeeded by a foliage leaf, 

 with its blade tightly inrolled (/j), whose stipules (st-^) enclose 

 the next foliage leaf (/g). The young stolon of the next genera- 

 tion {ax2) is also present in the bud. Fig. 24 5 (i) shows a bud 

 at a later stage in which the first foliage leaf is fully expanded 

 and the root has grown to a considerable length. 



St. ^ P 



Fig. 25. Hydrocharis Morsus-ranae, L. A, T.S. leaf; B, tangential section through 

 leaf at level of arrow in ^ ; C, upper epidermis with open stomates (x 78 circa) ; 

 St. = stomate; ac. = air cavity; d^ = diaphragm in section; d^ = diaphragm in 

 surface view; /= fibres; vb. = vascular bundle; xy. = xylem; ph. = phloem; 

 ue. upper epidermis; le. = lower epidermis; c thin layer of cuticle on upper 

 surface ; p = palisade parenchyma. [A. A.] 



The structure of the lamina of Hydrocharis may be described 

 in some detail as an example of the anatomy of a floating leaf 

 (Fig. 25). The upper surface is clothed with an epidermis 

 whose cells contain a few chlorophyll grains. The outer wall 

 is sculptured internally, and bears a delicate layer of cuticle 

 externally. The stomates, which are confined to the upper 



1 Gluck, H. (1901). 



