The individual plants of this common species are small and inconspicuous, but they often form dense swards around the shelving margins of lakes. These photographs are of such a sward at Castlwellan Lake in Co. Down where they form a broad green stripe around the lake shore. The zone of growth can range from just above the normal water level down to about 12 feet below.
The plants consist of tufts of short rigid semi-cylindrical leaves a few inches in length growing from a slender creeping stolon. Flowers are tiny and greenish and usually only produced on the plants growing above the waterline.
The non-flowering submerged plants bear a superficial resemblance to quillwort (Isoetes lacustris) and water lobelia (Lobelia dortmanna).
All names: Littorella uniflora (L.) Asch.; Littorella lacustris L.