28 



NYMPHAEACEAE 



[CH. 



like so many matters well known to the ancients in the nine- 

 teenth century 1 . 



These submerged leaves, which are stomateless, are charac- 

 teristically produced in the winter and spring 2 , and are usually 

 succeeded, in the course of the season, by floating leaves; in 



FIG. 13. Castalia alba, Greene. Seedlings of various ages illustrating the effect of 



sowing at different levels on or in the mud (M) at the bottom of the water (W) ; 



accommodation takes place in length of first internode, acicular first leaf, and 



petiole of second leaf with ovate lamina. [Massart, J. (1910).] 



deeper, rapidly flowing water, however, foliage of the submerged 

 type may be exclusively produced for years, even when the 

 plant is so old as to have a massive rhizome 3 . If the water does 



1 The submerged leaves of Nuphar minima^ Smith, were described by 

 Spenner, F. C. L. (1827). 



2 Costantin, J. (1886). 3 Goebel, K. (1891-1893). 



