Shellflower Pistia stratiotes Play pronunciation

Water lettuce is a floating aquatic, poisonous plant in the arum family (Araceae). It is thought to be native to the regions around the Nile River but is now found in nearly all tropical and sub-tropical fresh waterways. It is considered invasive and a mosquito breeding habitat. It has been found as far north as Minnesota and Connecticut in this country, including in North Carolina

It forms large dense mats of plant matter which hinder boating, fishing, and other lake and river activities and depletes oxygen levels and kills fish. It can be very invasive in locations with year-round warm temperatures and high humidity. In colder climates, it survives by reseeding itself.

The rosette of leaves resembles floating heads of lettuce with roots hanging below. Small flowers without petals are hidden amongst the leaves. It produces plantlets on short floating stolons to form mats.

Control is by herbicides, physical removal and biological control with two species of insects.

It is sometimes used in aquariums. See some native alternatives to the left.

Insects, Diseases, and Other Plant Problems:  No serious insect or disease problems. Watch for aphids. This plant is listed as invasive in NY, LA, TX, CA, SC, AL, CT, NH, DE, MI and FL and is on watch lists in other states. The EU has banned the sale of this plant.