44 HYDROCHARITACEAE [CH. 



interpreted as paired axillary stipules, whose leaf-blade is 

 generally rudimentary 1 . They are succeeded by a foliage leaf, 

 with its blade tightly inrolled (/J, whose stipules (j/J enclose 

 the next foliage leaf (/ 2 ). The young stolon of the next genera- 

 tion (tf# 2 ) is also present in the bud. Fig. 24 B (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. <* 



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

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

 st. = stomate; ac. air cavity; d v = diaphragm in section; d z = diaphragm in 

 surface view; /= fibres; vb. = vascular bundle; xy. = xylem; p h. = 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 Glttck, H. (1901). 



