Halpern 2002 states that, \"H. morsus-ranae is a floating-leaved monocotyledonous plant whose round, quarter-sized leaves may remind you of miniature lily pads. Each plant has numerous, fibrous, free floating roots which can attain a maximum lngth of 30cm. In early summer, the plants produce small, white, three petaled, unisexual flowers. Despite profuse flowering during the summer, H. morsus-ranae rarely produces seeds and instead relies on vegetative reproduction. Multiple plantlets develop along the stolons, or runners, of each plant during the growing season. In the fall, Eurasion frogs-bit produces buds, called turions, which sink to the substrate where they remain dormant until the springtime, at which time the developing buds floats to the surface and mature. One plant is capable of producing about one hundred of theses turions each year.\"
Delisle et al.. (2003) state that, \"Although the proportion curves of H. morsus-ranae suggest that the range of this species is still expanding, it will probably not expand north-eastward along the St Lawrence River because of the salinity of surface waters and the scarcity of large riverine wetlands east of Trois-Pistoles (Catling & Porebski, 1995; Lachance & Lavoie, 2002, in Delisle et al. 2003). Nevertheless, Delisle (2002, in Delisle et al. 2003) found a H. morsus-ranae population in 2001 in a freshwater drainage ditch at St Roch-des-Aulnaies, which represents a major (93 km) north-eastward expansion of the range of this species.\" Halpern 2002 states that, \"Connected waterways canals, and watersheds facilitate its dispersal, and boats and waterfowl can transport both turions and plantlets, expediting the expansion from one region to another.\"
Scribailo and Posluszny (1984) report that, \"The white, trimerous flowers of H. morsus-ranae are emergent and unisexual, with male flowers clustered in a cyme of up to 5 buds and females always solitary. Both sexes of flowers, once open, last a single day, with individual male flowers opening sequentially from a given inflorescence but not necessarily on successive days. The flowers produce a sweet nectar and scent which attract, and are easily accessible to, a wide variety of insects visiting the open bowl-shaped flowers. The most abundant insect visitors to the flowers were Homoptera (Aphididae) and Hydrellia and Notiphila spp. (Diptera: Ephydridae). Both groups were found to carry small pollen loads and because of their erratic anthophilous behaviour were not considered important in pollination. Although fewer in number, the more specialized hover flies, Toxomerus marginatus (Say) (Diptera: Syrphidae), and solitary bees, Dialictus sp. (Hymenoptera: Halictidae), were considered more likely to be the primary pollinators. After pollination and the day after anthesis, female flowers are drawn underwater by pedical recurvation and 4-6 wk later mature into globose berrylike fruits.\"
Compiler: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Review: Dr. Paul M. Catling \ Research Scientist and Curator \ Biodiversity, National Program on Environmental Health \ Agriculture and Agri-food Canada, Research Branch Ottawa Canada
Publication date: 2005-08-29
Recommended citation: Global Invasive Species Database (2020) Species profile: Hydrocharis morsus-ranae. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=862 on 31-10-2020.