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Elodea canadensis Michx. Common on alluvial bottom with 
Ceratophyllum, especially in quiet waters, but not reaching the 
surface so generally. It is widely distributed and is next in 
abundance to the preceding species, though forming a very 
much smaller proportion of the total vegetation. 
Vallisneria spiralis lL, Rare; found only in channels with 
currents, as at the mouth of Quiver Creek. 
Pontederia cordata L. Common along open places, such as 
the channels at the head of Quiver Lake and the outlet of Flag 
Lake, on both alluvial and sandy bottoms. 
Heteranthera graminea Vahl. Creeping along margins of 
lakes and the river, usually on alluvium. 
Juncus acuminatus Michx. Common in shoal water along 
sandy shores. 
Typha latifolia L. Oceasional patches found in the swamps 
and sloughs of the permanent backwaters. 
Sparganium eurycarpum Engelm. Frequent inthe margins 
of lakes and sloughs along channels on sandy and alluvial bot- 
toms. 
Spirodela polyrrhiza Schleid. Everywhere in quiet waters, 
forming in places dense mats upon the surface. Often drifted 
by wind or current in great windrows along shore. Very com- 
mon in open water, usually but not always on the surface. 
Often taken in the plankton with other species of the family. 
Lemna trisulca L. Locally abundant in the more open veg- 
etation of the backwaters in quiet bays and nooks in both sur- 
face and deeper waters. Not generally distributed, and less 
abundant than other members of the family. 
Lemna minor L. Associated with Spirodela but much less 
abundant. 
Wolffia columbiana Karsten. In surface and deeper waters 
in both river and backwaters among vegetation and in open 
water. Frequently taken in the plankton. 
