Chestnut - Trapa natans
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Water-chestnut is an annual with elongate, mostly simple stems which
grows submersed, rooted in the substrate. Leaves are of two types: (1)
submersed ones are alternate, sessile, linear and entire, falling off
early in the growth of the stem, and (2) a rosette of floating leaves
with inflated petioles to 15 cm long, the blades diamond-shaped (4-sided)
or nearly triangular with toothed margins, the upper surface glossy and
the lower surface pubescent. After the submersed leaves drop off, green,
adventitious (occurring out of order) roots, up to 8 cm long, that are
pinnately dissected into filiform segments develop in their place. These
roots are often mistaken for leaves. The flowers are above the water surface,
solitary on axillary peduncles. The petals are white, about 8 mm long.
The fruit is a woody or bony nut, about 3 cm wide, with stout spines.
Plants grow rooted in soft mud in lakes, ponds, canals and slow backwaters
and bays of rivers, in up to 5 m of water. Mature nuts sink to the bottom
and may germinate for 1 year. If they are air-dried they die. These edible
nuts are dispersed by animals and by water.
Plants form large populations and may be very troublesome to navigation,
fisheries and recreation.
Links to more information
Website, video, and graphics by Rob Nelson
For more information on this plant or management please contact US Army Corp of Engineers