Ottelia alismoides is a submersed aquatic herbaceous plant that is native to Africa, Asia, Australia, and the Pacific. The plant is entirely submersed except for the flower. Its common name, duck lettuce, comes from the strong resemblance the leaves of O. alismoides bears to lettuce leaves.
Foliage
The leaves of O. alismoides are completely submersed. Leaf blades are lanceolate to widely ovate, ranging from 4-10 in. (10-25 cm) long. The veins in the leaves run parallel.
Flowers
The small terminal flower is held on a long peduncle which projects it above the surface of the water. The flower may open fully even when still submersed. Flowers of O. alismoides have obovate petals that range from white to pinkish in color with bright yellow anthers. They bloom from spring through summer.
Fruit
O. alismoides reproduces only by seed. The ribbed oblong fruits range from 0.05-0.13 in. (15-40 mm) long with a beaked tip. It can produce up to 2000 seeds.
Ecological Threat
Ottelia alismoides is a federally listed noxious weed. It can be found Louisiana, California, Missouri and Florida. It was reported in waterways along the border between Texas and Louisiana. O. alismoides prefers habitats with shallow water from about 0-164 ft. (0-50 m) deep. This may include bayous, pools, and lakes.