Trapa natans


History
- Introduced to U.S. before 1879 by a gardener in Cambridge, Massachusetts, who planted it in several ponds
- Native to warm temperate regions of Eurasia
Characteristics
- Rooted, annual, aquatic plant with submerged and surface leaves
- Surface leaves are waxy and triangular with toothed edges
- Submerged leaves are feathery and whorled around the leaf stalk
- Stems can grow up to 16 ft (4.8 m) long
- Forms dense, floating mats
- White flowers
- Nut-like fruit with 2-4 spines
Habitat
- Lakes, ponds, slower sections of rivers and streams
- Prefers nutrient-rich water with a neutral to slightly alkaline pH
- Can grow in water up to 16.5 ft (5 m) deep, but prefers shallow water (1-6.5 ft, 0.3-2.0 m)
Known Distribution in the Northeast
- Connecticut, Massachusetts, New Hampshire, New York, Quebec, Rhode Island, Vermont
Impacts
- Dense, floating mats restrict light availability, reduce the oxygen content, and displace other emergent and floating vegetation
- Impedes boating, fishing, swimming and other recreational activities