Greater Duckweed - Spirodela polyrhiza

This is an aquatic plant, usually growing in dense colonies, forming a mat on the water surface. Each plant is a smooth, round, flat shiny green disc on top and often purplish underneath. It may measure 4 to 10 mm across and produces several minute roots (at least two, unlike Common Duckweed).

Lemna species

Many roots, large fronds, reddish underside and turns red in autumn, multiple veins

You must attach images that show sufficient detail for the plant to be identified.

Mainly found in still water such as ponds.

Spring and summer, dying back in the autumn.

Perennial.

British records are mainly concentrated in central and southern England.

It is near scarce in Leicestershire and Rutland. In the Flora of Leicestershire (Primavesi and Evans 1988) it was found in 7 of the 617 tetrads.