Common Frogbit is a free-floating aquatic plant with long hanging roots. New plantlets form at the end of its long runners, often building huge floating colonies.
Description
Common Frogbit is a dioecious plant, meaning male and female flowers are found on different plants. However, "normally flowering" plants may also be observed and have atrophied stamens. This perennial grows from 15 to 30cm (to water surface) and has rounded leaves which enclose the stalk in the shape of a heart. Each flower has three white petals and a yellow centre; male flowers (1 to 5) are stalked and grow from a bract whereas female flowers grow singly. The petals look slightly crumpled and are around 1cm long. Flowering takes place from May to August.
Distribution
Except for Tyrol and Vorarlberg, where Hydrocharis morsus-ranae is not found, and Carinthia, where the species is rare and perhaps extinct, there is scattered occurrence in the rest of Austria. Natural range extends to eastern Central Europe.
Endangerment and Conservation Status
Endangered and vigorously protected.
Ecological Characteristics
Common Frogbit thrives in stagnant or slow-moving waters rich in nitrogen and minerals but low in chalk and in partial shade.
Special Characteristics
In addition to sexual reproduction, Common Frogbit can also reproduce by vegetative means: strong cord-like runners called stolons are sent out from the rosettes; these build new plantlets at their ends. To over-winter, the plant forms turions, or winter buds, in the autumn, which fall to the bottom of deep waters to "hibernate". In the following spring, these buds rise to the surface as new plants.