Scientific name: Spirodela polyrhiza (L.) Schleid.
Common name: Greater Duckweed
Description
Habit: The base of each tassel of roots is subtended by a small scale bearing minute hairs.
Fronds: Fronds floating, with 7-16(-21) roots, round or broadly oval in outline, apex round, entire, fairly thick, opaque, more or less flattened on both surfaces, 5-8mm across, the dorsal surface dark green and shining, the ventral surface often purplish; each with a tassel of several roots and more than 7 indistinct veins.
Habitat: Ditches, pools and lakes.
Distribution: Abundant in the Lough Neagh basin, rare elsewhere.
Native status: Native
Of conservation interest: No