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^ 



B 



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. 156-6, November 23, 1914. (Both x 78 circa.} ep. = epidermis. [A. A.] 



and in the drupe-like one-seeded nutlet of Hippuris vu/garis 1 . 

 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 1 or as composed of pectic 

 substances 2 . In the case of the four nutlets into which the 



1 Fauth, A. (1903). 2 Crocker, W. and Davis, W. E. (1914). 



