Callitriche heterophylla

Large Water Starwort

NATIVE TO MAINE

Habitat: Large water starwort grows in the submersed and floating leaf plant communities. This plant is generally found in quiet, cool (often spring-fed) waters, preferring muddy or sandy substrates.

Description: : Large water starwort has fine stems that are 10 to 20 cm long. The submersed leaves are opposite, and arranged in pairs or in groups of three. The delicate leaves are simple, entire and variable in appearance. The submersed leaves tend to be pale green and linear. The upper leaves are more rounded (5mm wide) and crowded at the tip, forming a rosette that floats on the surface. The flowers grow in the axils of the leaves and produce very small capsule-like fruits (1 to 1.4 mm). The fruits are just 1 mm wide with shallow grooves, but no wings. The surface has pit-like markings, but they are not in rows. This plant is very similar in appearance to common water starwort. The fruits may be needed to distinguish between the two species.

Range: Large water starwort is a native plant species. It may be found throughout much of the U.S.

Annual Cycle: Large water starwort is an annual that reproduces by seed and stem fragments. Because the plant is adapted to cool water, growth begins early and flowers bloom in early summer. Seeds are mature by mid to late summer.

Value in the Aquatic Community: Ducks and other waterfowl feed upon the stems and fruits of large water starwort. Colonies of this plant provide food and shelter for fish.

Look Alikes: Brazilian elodea, hydrilla, common waterweed, and common water starwort.