plant · Araceae
Giant duckweed
Spirodela polyrhiza
Wild range: Nearly worldwide in temperate to tropical still freshwaters; Tropica lists North America as trade origin label (Cosmopolitan)
At a glance: Giant duckweed care
Compiled reference information. Review the care notes and original sources below.
What temperature is listed for Giant duckweed?
The compiled profile lists 18.0–29.0 °C for Giant duckweed (Spirodela polyrhiza). Check the original sources below for context and differing recommendations.
What tank size is listed for Giant duckweed?
The profile lists a minimum tank volume of 2.5 US gallons (10.0 liters). Volume alone does not establish suitability; consider dimensions, group size and other inhabitants alongside the full care notes.
What pH is listed for Giant duckweed?
The compiled profile lists a pH of 6.5–7.5. Review the cited care sources alongside the other water parameters in this profile.
Natural habitat
Largest common duckweed: round fronds about 0.5–1 cm across, often reddish beneath, with a tuft of many roots (typically 7–21) per frond. Floats in colonies on eutrophic ponds and slow waters.
Where they are found
Almost cosmopolitan in temperate–tropical climates (Flowgrow, Wikipedia). Less common in parts of South America (S. intermedia replaces it there). Tropica plant card Origin: North America. Orthographic variant Spirodela polyrrhiza used by Tropica and preferred by ITIS; catalog uses S. polyrhiza (Wikipedia/Flowgrow/APF spelling).
Aquarium care
Float on the surface—no substrate or CO2 injection needed. Low to moderate light; Tropica rates light demand Low and CO2 Low. Grows fast and exports nutrients well; thin regularly so it does not blanket the tank. Larger fronds make netting far easier than Lemna minor. Prefer calm surface or a floating ring. Check new portions for hitchhiking common duckweed if you want to keep Lemna out. Never release into local waterways.
Compatibility
Peaceful community floater; longer root tufts give better shrimp/fry cover than common duckweed. Same shading risk to submerged plants if unchecked. Easier to remove than Lemna because fronds are larger and net in sheets.
Photographs
Sources
Compiled from multiple independent care sheets — not copied from a single site.