Taxon	Illustrator ⠉
	Limnobium spongia Ottelia alismoides Vallisneria americana	John Myers John Myers John Myers

Plants annual or perennial, of fresh waters. Rhizomes and stolons absent [present]. Erect stems rooted in substrate, unbranched, short. Leaves basal, submersed [floating], petiolate; blade lanceolate to reniform [linear], base cuneate to cordate, apex rounded to acute; midvein without rows of lacunae along sides, blade uniform in color throughout; abaxial surface without prickles or aerenchyma, smooth; intravaginal squamules entire. Inflorescences scapose, long-pedunculate; spathes winged or ribbed. Flowers bisexual [unisexual, staminate and pistillate on different plants], sessile [staminate pedicellate], floating or occasionally opening under water; petals white to pink or light violet, often yellow at base; filaments distinct; pollen in monads; ovary 1-locular; styles 3–9, not 2-fid. Fruits oblong, ridged, dehiscing irregularly. Seeds fusiform, covered with hairs.

Distribution

Introduced; North America, South America, Asia, Africa, Australia

Discussion

Species 21 (1 in flora).

Selected References

Cook, C. D. K., J.-J. Symoens, and K. Urmi-König. 1984. A revision of the genus Ottelia (Hydrocharitaceae). I1. Generic considerations. Aquatic Bot. 18: 263--274.

Cook, C. D. K. and K. Urmi-König. 1984. A revision of the genus Ottelia (Hydrocharitaceae). 2. The species of Eurasia, Australasia, and America. Aquatic Bot. 20: 131--177.

Holmes, W. C. 1978. Range extension for Ottelia alismoides (L.) Pers. (Hydrocharitaceae). Castanea 43: 193--194.

Turner, C. E. 1980. Ottelia alismoides (L.) Pers. (Hydrocharitaceae) — U.S.A., California. Madroño 27: 177.

Lower Taxa

Ottelia alismoides