Greater Duckweed - Spirodela polyrhiza

    Description

    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).

    Identification difficulty
    Habitat

    Mainly found in still water such as ponds.

    When to see it

    Spring and summer, dying back in the autumn.

    Life History

    Perennial.

    UK Status

    British records are mainly concentrated in central and southern England.

    VC55 Status

    Occasional in Leicestershire and Rutland. In the 1979 Flora survey of Leicestershire it was found in 7 of the 617 tetrads.

    Leicestershire & Rutland Map

    UK Map