Key to Plants normally living in Water 
It is obviously difficult to distinguish between "aquatic" and 
"terrestrial" plants since many are able to accomodate themselves to 
varying degrees of submergence or desiccation, For example, Nympho- 
zenthus polysepalus is ordinarily an aquatic growing in several feet 
of water yet it may be founc late in summer groving in some places in 
quite dry grounde 
O ta,Plants with floating eee es a 4-leaved clover Marsilea 
6 {6 Plants not as described 
wee ee 
Z, Plants with erect hollow stems which bear minute triangular 
J leaves closely pressed to the joints, the branches when 
eS present appearing in whorls at the joints (Horsetails) Equisetum pf 
- Plants not as described 
4 2a.Minute plants not rooting)but floating on the surface, 
“@ forming a scum 
‘, Each disc-like leaf bearing 2 or more rootlets which hang 
+ in the water Spirodela ( 4 
_, Bach disc-like leaf bearing a single rootlet Lema |, — 
4 2b. Plants not as described 
{, Leaves reduced to basal scales, sccmingly one; rushes 
f/f 1-3 m,. tall Scirpus (p: 
., Leaves obvious 
“ Leaves trifoliolate, the leaflets 3.5-7 cm. broad Menyanthe s (p. a 
