pond scum

pond scum, accumulation of floating green algae on the surface of stagnant or slowly moving waters, such as ponds and reservoirs. One of the commonest forms is Spirogyra.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on pond scum from Fact Monster:

See more Encyclopedia articles on: Moneran and Protistan