i] BIOLOGICAL CLASSIFICATION 7 



E. Plants which in some cases may occur as land forms, but 

 which are very commonly submerged, and are characterised by 

 an abbreviated axis from which linear leaves arise. 



(i) Inflorescence raised above the water or borne on a land 

 plant. 



E.g., Lobelia Dortmanna, L. (Water Lobelia). 

 Littorella lacustris, L. 

 Sagittaria teres, Wats. 



(ii) Inflorescence sometimes raised above water or some- 

 times submerged. 



E.g., Subularia aquatica, L. (Awlwort). 



F. Plants which are entirely submerged as regards the vege- 

 tative organs and which have a thallus (morphologically either 

 of root or shoot nature) attached to the substratum. The 

 flowers are aerial. 



Tristichaceae and Podostemaceae. 



II. Plants which are not rooted in the soil, but live unattached in 

 the water. 



(A transition between I and II is found in Stratiotes aloides, 

 L. (Water Soldier), which is rooted during part of the year but 

 floats freely during another part. There are also a number of 

 rooted plants, such as Hottonia -palustris and Elodea canadensis, 

 which are capable of living unattached for considerable periods.) 



A. Plants with floating leaves or leaf-like shoots. Flowers 

 raised into the air. 



(i) Roots not penetrating the soil. 



E.g., Hydrocharis Morsus-ranae, L. (Frogbit). 



Spirodela polyrrhiza, Schleid., 1 (Duck- 

 Lemna minor, L. and L. gibba, L.J weeds). 



(ii) Rootless. 



Wolffia (Rootless Duckweed). 



