SLELO PRISM

Invasive frog-bit (Hydrocharis morsus-ranae) is a free-floating plant that resembles a miniature version of water lily. Its small leaves are distinctly heart-shaped and its white flowers have three petals. Native to Eurasia, the plant can quickly form dense floating mats in wetlands and other slow-moving water systems.

Impacts

Frog-bit prefers quiet, slow-moving waters and can blanket shallow ponds, marshes, and the edges of lakes. It can reduce the growth of native submersed aquatic plants and has the potential to impact recreation.  Thick mats of frog-bit inhibit light penetration and hinder the movement of fish, waterfowl, and boats. Viable plant fragments can spread to new locations by boaters.

Identification

Leaves: thick, heart-shaped, 1 to 2 inches wide, and smooth-edged with spongy, purplish-red undersides.

Flowers: small, showy flowers are ½ inch across, appear singly, and have three white petals and yellow centers.

Roots: 3 to 8 inches long and unbranched, dangling from the underside of each rosette of leaves.

Reproduction: Frog-bit can spread by sending out stolons which produce ‘daughter’ plants that break free and float to new locations. Also produces turions — compact winter buds that sink to the bottom in fall and float back up in spring to grow into new plants.

Control/Management

Plants can be collected by hand or mechanical harvesters, with all parts composted away from wetlands, rivers, or lakes. Care must be taken to prevent plant fragments from escaping the infestation site. Sites should be checked annually for reinfestations. Use of chemical herbicides also effective.

For more information:

Managing Invasive Frogbit through Research and Education in New York’s Great Lakes Basin: A Project of the Finger Lakes Institute, Hobart and William Smith Colleges, Cornell University and Cornell Cooperative Extension of Onondaga County

Photo Credits: invasive.org Leslie J. Mehrhoff, University of Connecticut, Bugwood.org