Floating pennywort
Hydrocotyle ranunculoides
Also known as Floating marsh-pennywort, American pennywort, Hydrocotyle natans
Invasive. Banned in the EU and Great Britain as an invasive alien species; sale has been prohibited in England and Wales since 2014. Never release into the wild; dispose of plants in the trash.
Care at a glance
- Light
- Medium light
- CO2
- CO₂ beneficial
- Growth rate
- Fast
- Placement
- Floating
- Type
- Floating
- Temperature
- 50–79°F (10–26°C)
- pH
- 6.0–8.0
- Hardness
- 4–18 dGH
- Max height
- 5.9 in (15 cm)
- Nutrient uptake
- Root + water column
- Growth region
- Submersed or emersed
- Difficulty
- Easy
- Origin
- The Americas (North, Central and South); introduced in Europe, Asia and Australia
- Family
- Araliaceae
Overview
A floating creeper for ponds and open-top setups rather than a fully submersed plant: it wants its leaves in the air, its roots trailing in rich water, and room to run. Growth is startling in warm weather, so treat trimming as mowing and keep every fragment out of drains and waterways. Where it is legal at all, it is best kept only in closed indoor systems.
In the wild
At home in slow, nutrient-rich lowland waters across the Americas, rooting at the margins and sending fleshy runners out over the surface, each node holding a glossy, ruffled, kidney-shaped leaf above the water. In its introduced range those runners build floating mats dense enough to cover whole channels, which is what earned it an EU-wide ban.
Good to know
A true pennywort in the ivy family Araliaceae, in the same genus as Brazilian pennywort but far larger in leaf and appetite. The epithet ranunculoides means buttercup-like, for the rounded, lobed leaf shape. Stems grow along the surface rather than upward, rooting at every node, and fragments as small as a single node regrow into new mats.
Did you know
In Britain its mats can lengthen by around 20 centimetres a day in high summer, fast enough that rivers are cleared by the barge-load, and it became one of the first plants ever banned for sale in England and Wales.
Appears in
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