228 FLOWERS OF AQUATICS [CH. 



and even within the same genus we find differing degrees of 

 success in the avoidance of submergence of the flower. Ranun- 

 culus fluitans, for instance, which does not hold its peduncles 

 well erect and grows in rapidly flowing water, very often suffers 

 from the inundation of its flowers, and, in consequence, fails 

 to set seed 1 . Sometimes the attempt to rise above the water 

 surface seems to have been entirely given up. Ranunculus 

 trichophyllus is described as growing in the River Inn in enor- 

 mous masses, and frequently blooming under water, opening 

 its flowers at a depth of I to I J feet, but whether it can set 

 seed under these conditions does not seem to have been ob- 

 served 2 . Those Batrachian Ranunculi which flower successfully 

 in rapidly flowing water, prove to be species such as R. carinatus, 

 Schur. (R. confusus, Gen. et Godr.) which produce long flowering 

 stalks rising erect above the water, and not readily submerged 

 by slight changes in level 1 . In the case of the heterophyllous 

 Water Buttercups, the leaves associated with the flower are often 

 floating and relatively undivided; this must be an assistance in 

 maintaining the equilibrium of the pedicel 3 . In Heteranthera 

 zosteraefolia^ also, the leaf next the inflorescence is described 

 as always being of the floating type 4 . The association of floating 

 leaf and flowers in Limnanthemum nymphoides, which is so close 

 that the inflorescence appears at first sight to spring from the 

 petiole, must also play a part in holding the flowers above water. 

 If any locality in which Limnanthemum grows freely be visited 

 in August, the way in which the fringed, yellow flowers are held 

 clear above the water will be found to be one of their most 

 striking characters. 



The early development and whorled arrangement of the 

 branches springing from the base of the inflorescence axis in 

 Hottonia palu stris 5 , the Water Violet, serve to support it on all 

 sides, and to keep it vertical, while the numerous adventitious 

 roots arising from the base of the erect shoot probably have a 



1 Freyn, J. (1890). 2 Overton, E. (1899). 



3 Aslcenasy, E. (1870). 4 Hildebrand, F. (1885). 



5 Schenck, H. (1885) and Prankerd, T. L. (1911). 



