Common Duckmeat

Spirodela polyrhiza has fronds that are 1.5-10 mm long and 1.5-8 mm wide, with 40-70 µm wide nerves and air spaces in 2-4 layers. It has 7-21 roots, with 1 or 2 possibly perforating the prophyll. The rootcap is rounded or pointed on living specimens, and pointed on dried ones. It produces small, brownish to olive turions under unfavourable conditions. The plant rarely flowers and fruits, with an ovary containing 1-2 ovules and a fruit 1.0-1.5 mm in size. Seeds are 0.7-1.0 mm long with 12-20 ribs and an 8-11 layer external seed coat. First published in 1839.