8 BIOLOGICAL CLASSIFICATION [ch. i 



B. Plants entirely or partially submerged. 



(i) Rooted, but roots not penetrating the soil. Floating 

 shoots, formed at flowering time, which raise the flowers 

 into the air. 



Lemna trisulca^ L. (Ivy-leaved Duckweed). 



(ii) Rootless. 



{a) Inflorescence raised out of the water. 

 Aldrovandia. 

 Utricularia (Bladderwort). 



ijy) Flowers submerged; hydrophilous pollination. 

 Ceratophyllum (Horn wort). 



