brittleleaf naiad

Najas minor All.

U.S. Nativity: Exotic
Habit: Aquatic

Synonym(s): brittle waternymph, brittleleaf naiad, European naiad, spinyleaf naiad, slender-leaved naiad

Najas minor is an herbaceous, aquatic annual with stems that can grow 4-7.75 in. (10-20 cm) long. These stems can be up to 0.04 in. (1 mm) thick.
The oppositely arranged, dark green leaves become recurved as they age, and have serrulate margins with 7-15 small teeth on each side. The leaf base is truncate or lobed. The leaves measure 0.2-1.25 in. (0.5-3.5 cm) long and 0.007-0.05 in. (0.1-1.2 mm) wide.
Najas minor is a monoecious plant, with 1-2 flowers per axil. The male flowers are located distally and are 0.08 in. (1.9-2.2 mm) in size. The involucre has two lobes and the beaks are 0.02-0.08 in. (0.4-2.1 mm) in length. The female flowers are located in the distal to proximal axils and measure 0.8 in. (2.2 mm) in size.
The spindle-shaped seeds of this plant are 0.05-0.1 in. (1.5-3 mm) in size and purple colored.
Ecological Threat
Najas minor has the ability to form thick stands that can cover or clog a lake or stream. This plant is extremely brittle, which allows it to fragment and get moved via boats, waterfowl and river channels. Waterfowl readily eat and move this plant from waterbody to waterbody. In North Carolina, this plant is reported to out-compete other exotics such as Hydrilla verticillata. This plant needs to be watched, contained or removed if found.

Identification, Biology, Control and Management Resources

Invasive Plant Atlas of New England - University of Connecticut