Red root floater
Phyllanthus fluitans
Also known asFloating spurge · Apple duckweed
Water parameters
Light and nutrients
Substrate type: floating. Propagation: fragmentation.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Bare bottom (no substrate) (Bare bottom) | n/a | none |
| Inert sand (Pool filter sand) | neutral / inert | none |
| Inert gravel (Aquarium gravel) | neutral / inert | none |
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
| Dirted tank (mineralized topsoil) (DIY soil substrate) | slightly acidic | very high |
| Wood and rock mounts (Hardscape mount) | varies | none |
With fish
Origin and habitat
A free-floating flowering plant, not a fern, of the family Phyllanthaceae, Phyllanthus fluitans, the red root floater (also floating spurge or apple duckweed), native to the Amazon basin of tropical South America across Peru, Ecuador, Colombia, Brazil, Bolivia, Venezuela, Paraguay and northern Argentina, with its type from a Rio Negro tributary. It floats on still and slow water, its short stems carrying small heart-shaped to round leaves 1–3 cm across, each with an air-trapping pocket either side of the midrib for buoyancy. Under strong light the leaves blush red and the trailing rootlets turn vivid scarlet, the colour that gives it both its name and its popularity. It spreads by budding daughter plants on short stolons into loose surface mats, faster than most submerged plants but slower than duckweed. Little known in the hobby before the 2010s, it spread through social media for its red colour and is now widely sold.
Outdoor pond use
- USDA zones
- 8–13 (winter low around -12°C or warmer)
Care notes
A decorative floater grown for its red leaves and roots, and the single biggest factor for that red is light: it stays green under low to moderate light no matter the nutrients, and needs bright light, roughly 50 to 120 PAR at the surface, to colour up. Iron is the other key, around 0.1 to 0.5 ppm dosed in the water column, which deepens the scarlet roots. It wants calm water, since strong filter flow shoves it about and damages the roots, so baffle the outflow or pen it behind airline or a floating ring. It pulls nitrate and phosphate from the water through its roots. It is happiest around 22–26°C, tolerates brief cold down to about 10°C, and tends to melt in heat much above the high 20s, so it is not really a coldwater plant but more cold-hardy than its tropical origin suggests. Growth is moderate, so thin it every week or two to stop it covering the surface and shading plants below. It propagates itself by daughter plants and can set seed. The trailing red roots shelter fry and shrimp. It is an ornamental floater, not a crop, so it is unsuited to media-bed aquaponics or hydroponics.