240 FRUITS OF AQUATICS [ch. 



the fruit is carried down by the sinking of the entire plant. The 

 lowering of the fruit must not, however, be regarded as a special 

 innovation due to aquatic conditions, since countless examples 



~'~^^'^(#f3. 



Fig. 155. Pontederia rotundifolia, L. Branch bearing inflorescence (negatively 

 geotropic) and infructescences (positively geotropic). (Reduced.) [Hauman- 



Merck, L. "(1913I).] 



occur among terrestrial plants, e.g. the spiral contraction of the 

 fruit stalk oi Cyclamen and the downward curve of the peduncle 

 of Lin aria Cymbalaria. 



In those submerged fruits which are many-seeded, the 

 method of dehiscence is necessarily different from that obtain- 

 ing among terrestrial plants, since desiccation can play no part. 

 The irregular opening of the fruit oi Nymphaea lute a has already 

 been described^. In the case of Limnanthemum nymphoides. 



* 



Fig. 156. Limnanthemum nymphoides, Hoffmgg. and Link. A, fruit from surface 

 of water, October i, 191 4 (nat. size). B, fruit kept in water in unheated greenhouse 

 since October i, which had dehisced by November 23 (nat. size). C, seed, Novem- 

 ber 24, 1914 (x 2). [A. A.] 



dehiscence takes place in a somewhat similar fashion. The 

 present writer found a number of infructescences of this plant 

 with green fruits (Fig. i ^6 A) floating on the surface of the 



1 See p. 35. 



