COMMON NAME
European frogbit
FULL SCIENTIFIC NAME
Hydrocharis morsus-ranae L.
FAMILY NAME COMMON
Frog's Bit family
FAMILY SCIENTIFIC NAME
Hydrocharis morsus-ranae
IMAGES
 Flower |
 Habit/Habitat |
NOMENCLATURE/SYNONYMS
Synonyms: None
DESCRIPTION
Hydrocharis morsus-ranae is an herbaceous, annual aquatic that can reach 20 cm (8 in.) in length. The plant is free-floating (unattached to the bottom substrate of the water body). The leaves of this plant are usually floating, but if the vegetation is dense enough, they can be emergent. The leathery, glabrous leaves are cordate-orbicular in shape and measure 1.2-6 cm (0.5-2.25 in.) in length and (0.5-2.5 in.) in width. The lower leaf surfaces are often dark purple in color. The lateral veins of the leaves are broadly arching, making a 75 to 90 degree angle in relation to the midvein. Hydrocharis morsus-ranae is a dioecious plant. One to five staminate flowers are contained in spathes borne on peduncles that measure 4 cm (1.5 in.) long. There is only one pistilate flower on each plant. The 3-petaled pistilate flowers are white in color with a yellow spot in the center. These flowers measure 1 cm (0.4 in.) across. The pedicels of the pistilate flowers measure 9 cm (3.5 in.) long. The seeds of Hydrocharis morsus-ranae are around 1 mm (0.04 in.) in size. This plant can also produce stolons, which allow it to reproduce asexually. It is able to form large colonies that appear as dense floating mats of vegetation. Page References Bailey 132, Crow & Hellquist 28, Flora of North America 21, Gleason & Cronquist 638, Holmgren 606. See reference section below for full citations.
SIMILAR SPECIES
Limnobium spongia (Bosc) Richard ex Steudel (American frogbit)
REPRODUCTIVE/DISPERSAL MECHANISMS
Hydrocharis morsus-ranae spreads rapidly by way of long, cord-like stolons, easily giving rise to a floating mat of interconnected plants. It is capable of over-wintering by forming vegetative buds, called turions, located at the base of the plant. Hydrocharis morsus-ranae is also capable of sexual reproduction, but seed production is often limited and sometimes non-existent.
DISTRIBUTION
Hydrocharis morsus-ranae is native to Europe. In North America it has spread from original sites in Ottawa, Canada to Quebec, the St. Lawrence River, Lake Erie and Lake Ontario. In the U.S. it is currently found at limited sites in the states of New York, Vermont, Michigan and Washington.
HISTORY OF INTRODUCTION IN NEW ENGLAND
Several plants from Zurich, Switzerland were placed in ponds near the Central Experimental Farm Arboretum of Ottawa in 1932. These apparently escaped and spread from the Ottawa region to the St. Lawrence River by the 1960s. In 1993, Hydrocharis morsus-ranae was found in Lake Champlain. By 1999 it was found south of Lake Champlain in several Vermont sites (Benson, Orwell and West Haven).
HABITATS IN NEW ENGLAND
,Aquatic,Lake or Pond,River or StreamHydrocharis morsus-ranae grows well in quiet open water. It can be found in marshes, ditches and swamps. It grows well in sheltered coves and along the still water shorelines of rivers, lakes and streams.
THREATS
Hydrocharis morsus-ranae has rapid vegetative spread and the ability to form dense mats, which can limit light penetration and fill the water column in shallow areas. In doing so it can strongly affect native aquatic life. It can also inhibit boat traffic and limit recreational activities.
MANAGEMENT LINKS
DOCUMENTATION NEEDS
Documentation required: Herbarium specimen or mounted snippet of the plant with flowers.
Best time for documentation: Summer, fall.
ADDITIONAL INFORMATION
Integrated Taxonomic Information System
Taxonomic information about the species
USDA Plants database
General information and map
Flora of North America
Extensive description
Environment Canada
Fact sheet with description and distribution of this plant in Canada
USGS Nonindigenous Aquatic Species
U.S. distribution information
University of Florida, Center for Aquatic and Invasive Plants
Images