Leaves submersed; blade lanceolate to widely ovate, to 17 ´ to 20 cm, margins entire to crisped. Inflorescences 1-flowered; spathes 3--10-winged. Flowers: sepals10--15 ´ 2--9 mm; stamens 3--12; ovary 1, 3--9-carpellate. Fruits 15--40 mm. Seeds to 2000.

Flowering spring--summer. Shallow water of bayous, pools, and lakes; 0--50 m; Calif., La.; Asia, Australia.

Ottelia alismoides is a quite distinctive member of our aquatic flora. It is the only species we have with flowers surrounded by a winged or ribbed spathe. The plant is entirely submersed except for the flower, which is projected to the water surface by the elongate peduncle. The flowers may open fully even when completely submersed.

First collected in North America in Calcasieu Parish, Louisiana, in 1939, Ottelia alismoides is a conspicuous weed of rice paddies and irrigation systems in the warmer countries of the Eastern Hemisphere. Propagules were probably inadvertently brought into North America with rice seed (D. H. Dike 1969).