242 FRUITS OF AQUATICS [ch. 



of seeds. The fruit of Littorella on the other hand is reduced to 

 a nut developed from the two-celled gynaeceum. Only one 

 chamber is fertile and the embryo is protected by means of the 

 sclerised fruit wall, with its aperture closed by a stopper formed 

 from the funicular region of the seed. A protective endocarp, 

 with an opening closed by a plug, is also found in the four one- 

 seeded segments of the schizocarp of Myriophyllum spicatum^ 



Fig. 157. Limnanthemum nymphoides, Hoffmgg. and Link. A, T.S. wall of fruit 



represented Fig. 156 A, p. 240, October i, 1914. B, T.S. wall of fruit represented 



Fig. 156 B, November 23, 1914. (Both x 78 circa.) ep. = epidermis. [A. A.] 



and in the drupe-like one-seeded nutlet of Hippuris vulgaris'^. 

 The seeds of the latter species winter in mud at the bottom of 

 the water, protected by the stony endocarp. At germination 

 the radicle emerges from the stone through a foramen which 

 was previously filled by a cuticularised stopper, formed from 

 part of the funicle and integument. In Alisma Plantago the 

 embryo is protected by a chaffy carpel wall and a testa described 

 by different authors as suberised^ or as composed of pectic 

 substances^. In the case of the four nutlets into which the 



1 Fauth, A. (1903). ^ Crocker, W, and Davis, W. E. (19 14). 



