Frogbit

Frogbit facts

Scientific name: Hydrocharis morsus-ranae

Family: Hydrocharitaceae

Origin: Native

Type: Perennial

Frogbit and our canals

This free-floating aquatic plant has flat, heart-shaped leaves which provide for fish, newts and other underwater species. Dragonfly nymphs also use them for shelter in their juvenile stage, whilst smaller fish and snails may graze on frogbit roots and the microorganisms they harbour.

Frogbit roots are also excellent water purifiers due to their ability to absorb excess nutrients. However, the roots can spread rapidly through their stolons, causing the plant to dominate in certain areas.

Frogbit is native to Europe and some parts of Asia, but was introduced to Canada in the 1930s and is an invasive nuisance for some of their open water spaces. Despite it being widespread in Britain, its presence is declining largely due to changes in land use, and it is now listed as vulnerable in the Red Data Book for Great Britain.

What does frogbit look like?

Frogbit's shiny, kidney-shaped leaves resemble those of a water lily. In July and August, it produces small, delicate white flowers with yellow centres. The tell-tale sign that they belong to frogbit is that they'll only ever have three petals.

If there are any spaces between its leaves, you'll likely be able to see its network of roots and stolons below the water, which can grow to depths of up to 12 inches.

Where to find frogbit

Frogbit flourishes in slow-moving or stagnant waters including canals, ponds and lakes. It prefers shade to full sun.

When to see frogbit

Frogbit is most noticeable in the summer months thanks to its bloom of tiny flowers. It survives winter by sending out small buds (called turions) to the bottom of the water, which remain dormant until spring when they rise to the surface and become new frogbit plants.

Other plant species to look out for