Lythraceae

Trapa species

Common Names: Floating water chestnut

Plant Form: Annual mat-forming aquatic herb. Size: Up to 1.5 m deep rooted. Stem: Long, submerged. Leaves: Submerged leaves are feather-like in whorls, surface leaves are in rosette, glossy on top and 2-3 cm long. Oval, triangle or diamond shaped, on stalks with a swollen round bulge. Flowers: Above water. White with four petals, 8 mm long. Fruit and Seeds: Hard woody nut with sharp spines, about 3 cm across, with one seed. Underneath the emerged leaves. Habitat: Ponds, lakes, dams, reservoirs, mudflats. Distinguishing Features: Swollen bulge on leaf stalks distinguish from lookalike Mosaic flower (Ludwigia sedioides).

Rhomboidal leaves and floats

Leaf undersurface

Seeds