[ 239 I 



CHAPTER XIX 



THE FRUITS, SEEDS AND SEEDLINGS OF 

 WATER PLANTS 1 



AS we have shown in the preceding chapter, submerged pol- 

 jt~\. lination represents an advanced stage in acclimatisation to 

 water life, to which only a small proportion of hydrophytes have 

 attained. But it is by no means so rare to find the events subse- 

 quent to pollination taking place beneath the water surface. 

 A great many aquatics not only those which are hydrophilous, 

 but also a number of those which raise their flowers into the air 

 for pollination by wind and insects after fertilisation draw 

 down their gynaeceum into the water where the ripening pro- 

 cesses take place. In fact, the water plants which retain an 

 entirely aerial method of fruit-ripening are relatively few; 

 examples of these exceptions are Utricularia, Hottonia and 

 Lobelia^ all of which lift their many-seeded capsules on long 

 infructescence axes above the water level. Numerous examples 

 of those aquatics which are pollinated in air but ripen their fruit 

 in water, might be quoted, but it will suffice to recall Aldro- 

 the Aponogetonaceae 3 , Limnanthemum Humboldtia- 

 Victoria regia 5 , the Batrachian Ranunculi (Fig. 93, p. 145), 

 Pontederia rotundifolitfi (Fig. 155, p. 240) and other members 

 of the Pontederiaceae 4 . Among the Hydrocharitaceae 7 , the 

 ripening ovary is conveyed down into the water by several 

 different methods; in Limnobium and Qttelia the flower-stalk 

 bends down, in Vallisneria it contracts spirally, while in Stratiotes 



1 For a good general account to that date, see Schenck, H. (1885). 



2 Caspary, R. (1859 and 1862). 



3 Krause, K. and Engler, A. (1906). 



* Muller, F. (1883). See p. 34. ' 



6 Hauman-Merck, L, (I9I3 1 ). 7 Montesantos, N. (1913). 



