The water chestnut is an annual aquatic plant not native to the United States, categorized as an invasive species in the Connecticut River Watershed. The water chestnut is a rooted, floating aquatic plant. It has rosettes of leaves that float on the surface of the water that appear to be radiating from a central point. They are triangular or slightly diamond shaped, toothed on two sides and connected to the stem by a long, flexible submerged stalk. Submerged leaves are feathery and either opposite or alternate. Very small, white four-petaled flowers bloom in July. The seeds are four-horned nut-like structures that mostly develop on the underside of the floating rosette. Seeds ripen in about a month (ripe seeds start to drop around the end of July or early-mid August).These seeds remain viable for up to twelve years. One seed can produce up to 15 rosettes, producing up to 20 more seeds, and quickly covering the water surface.
llustration by Pam Burns from *Aquatic Plants of New England Series: Trapa natans, Crow and Hellquist 1983*
What is the problem? Why is it an invasive plant?
The water chestnut hogs space and nutrients, preventing other plants and animals from living there. The decomposition of foliage decrease amounts of dissolved oxygen which severely damages fish and other aquatic life’s ability to survive. Then there’s the fruit–the spiny seeds hurt if stepped on! Water chestnut infestations also impede fishing, hunting, swimming and boating as the rosettes cover entire bodies of water up to sixteen feet deep. Management of out of control infestations is costly! However, this plant can be kept in check and prevented from invading new ponds and coves by removing plants before they have a chance to set seeds.
How can I help?
River Sweep Event | Saturday, June 24th | Adopt a Section of the River! Click here to learn more!
Hand Pulling Events | Various Dates | Pulling events typically occur from June through August throughout Connecticut, Massachusetts, Vermont and New Hampshire. Events are part of a multi-organizational collaboration united in the goal of removing this invasive plant. Pulling is easy, interesting and a great reason to get out on the water! To learn more about the events currently scheduled click here!
Please report sightings in the Connecticut River watershed to the following contacts and/or report via the online resources below.
Or on EDDMapS : Simply register as a user (free) and follow prompts to make a report **These reports will be verified before being added to the map on EDDMapS, so there may be a delay before your sighting is added to the map**
Outsmart Invasives App: An app sponsored by EDDMapS for more convenient reports