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Ducklettuce

(Ottelia alismoides)

Photo of ducklettuce
Photo credit: J. Garg

A common submerged plant in warmer Asian countries often found in irrigation systems and rice paddies. It spreads by seed and is on the federal noxious weed list in the United States.

Overview

Other names for this plant include:
  • Scientific names: Stratiotes alismoides
Ecological threat:
  • It can invade freshwater lakes, reservoirs, ponds, marshes and ditches making boating, fishing and almost all other water activities difficult.
  • Degrades water quality by blocking the air-water interface and greatly reducing oxygen levels in the water, impacting underwater animals such as fish.
  • Greatly reduces biological diversity: vegetation mats block sunlight, preventing the growth of submerged and emersed plant communities and also alter animal communities by blocking access to the water and/or reducing plants the animals depend on for shelter and nesting.
Overview map of prohibited classification in WI
Prohibited (red) counties

Classification in Wisconsin: Prohibited

Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for ducklettuce was based upon this literature review [PDF] developed by the department.

Identification

Leaves: Oval green leaves submerged, sometimes partly emergent in shallow water.

Flowers: White, three petals with a yellow blotch at the center

Fruits & seeds: small oval tan seeds are the primary method of spread.

Similar species: May be confused with other aquatic plants such as Echinodorus berteroi.

Distribution

Currently, there have been no reports of ducklettuce in Wisconsin. Have you seen it? Send us a report.

Control

Mechanical: Very small populations can be controlled by pulling. Physical removal should be completed before flowering and seed set.

Chemical: Registered aquatic herbicides can provide temporary control of ducklettuce in small scale applications. Application of aquatic herbicide requires a permit.

Photos

View ducklettuce pictures in our photo gallery!

Resources

Sources for content: Links for more information: