This section is from the book "Wild Flowers Of The North American Mountains", by Julia W. Henshaw. Also available from Amazon: Wild Flowers of the North American Mountains.
An aquatic herb. Stems: submerged ones linear, bifid at the apex; floating ones obovate, obtuse, dotted with stellate scales. Fruit: compressed, lobed, winged only towards the apex, separated by a deep groove.
This plant is found chiefly in running water, or growing in the mud. It has minute flowers and a lobed winged fruit.
 
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