Plate 1 figs. a–h · 8 separate observations
Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.
Native range 203 botanical countries
Not drawn on the map: Kuril Is., Cocos (Keeling) Is., Great Britain, Mexican Pacific Is.. We hold no public-domain boundary for these regions, so they are listed rather than guessed at.
Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.
Where it actually grows measured, from 1,985 observations
| Condition | 5th percentile | Median | 95th percentile |
|---|---|---|---|
| Coldest month, mean daily low | -18.6 °C | -6.5 °C | 8.5 °C |
| Warmest month, mean daily high | 20.8 °C | 24.5 °C | 31.7 °C |
| Annual rainfall | 478 mm | 755 mm | 1,482 mm |
| Rainfall in the driest quarter | 52 mm | 120 mm | 262 mm |
It is found where winters are severely cold. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,985 research-grade observations of Spirodela polyrhiza that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.
This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one.
Also published as 21 synonyms
A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.
- Lemna bannatica Waldst. & Kit. ex Schleid.
- Lemna major Griff.
- Lemna maxima Blatt. & Hallb.
- Lemna obcordata P.Beauv.
- Lemna orbicularis Kit. ex Schult.
- Lemna orbiculata Roxb.
- Lemna polyrhiza L.
- Lemna polyrhiza var. concolor Kurz
- Lemna polyrrhiza var. concolor Kurz
- Lemna thermalis P.Beauv.
- Lemna thermalis P.Beauv. ex Nutt.
- Lemna transsilvanica Schur
- Lemna umbonata A.Braun ex Hegelm.
- Lenticula polyrhiza (L.) Lam.
- Spirodela atropurpurea Montandon
- Spirodela atropurpurea Friche-Joset & Montandon
- Spirodela maxima (Blatt. & Hallb.) McCann
- Spirodela polyrhiza var. masonii Daubs
- Spirodela polyrrhiza var. masonii Daubs
- Telmatophace orbicularis (Kit. ex Schult.) Schur
- Telmatophace polyrhiza (L.) Godr.
Sourcesevery claim on this page
- World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
- iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
- Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
- Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.
We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.