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 (Bladder wo it). 



() Flowers submerged; hydrophilous pollination. 

 Ceratophyllum (Horn wort). 



