Glyceria maxima(Hartm.) Holmb.

reed mannagrassreed sweet-grass

WFO wfo-0000873262 Accepted WFO 2026-06 8 photographs CC0 / CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Glyceria maxima, photographed by Anastasia_Surkova
fig. a Anastasia_Surkova, CC BY 4.0 / 2022-06-04 / obs. 204158263
Glyceria maxima, photographed by Arnim Littek
fig. b Arnim Littek, CC BY 4.0 / obs. 181931097
Glyceria maxima, photographed by Olha Sira
fig. c Olha Sira, CC BY 4.0 / obs. 159902289
Glyceria maxima, photographed by Константин Селивёрстов
fig. d Константин Селивёрстов, CC BY 4.0 / obs. 153905199
Glyceria maxima, photographed by Aleksei Baushev
fig. e Aleksei Baushev, CC BY 4.0 / obs. 153763628
Glyceria maxima, photographed by Aleksei Baushev
fig. f Aleksei Baushev, CC BY 4.0 / obs. 152244836
Glyceria maxima, photographed by Piermario Maculan
fig. g Piermario Maculan, CC0 1.0 / obs. 149280412
Glyceria maxima, photographed by Grzegorz Grzejszczak
fig. h Grzegorz Grzejszczak, CC BY-SA 4.0 / obs. 176890217

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.

The specimen a real sheet, in a real collection

Herbarium
Royal Botanic Gardens, Kew
Accession
K003211440
Filed as
Glyceria maxima (Hartm.) Holmb.
Det. by
Brightly, W.
Collected
Schipczinsky, N.
Origin
RU
The sheet
View the digitised specimen (CC BY 4.0)

A real pressed plant, in a real collection, under the accession number above. Not an illustration of one. The holding institution does not serve this sheet’s image to third parties, so there is no photograph here. The record is real and the link goes to it. Where we hold no openly licensed sheet for a species this section is simply absent, and where a sheet never recorded who determined it, that field stays empty rather than being filled in. Roughly half of all herbarium sheets never recorded a determiner, which is ordinary.

Native range 35 botanical countries

Regions where Glyceria maxima is native: Kazakhstan, Transcaucasus, West Siberia, Xinjiang, Austria, Baltic States, Belarus, Belgium, Bulgaria, Central European Russia, Czechia-Slovakia, Denmark, East European Russia, Finland, France, Germany, Great Britain, Greece, Hungary, Ireland, Italy, Netherlands, North European Russia, Northwest European Russia, Norway, NW. Balkan Pen., Poland, Romania, Sardegna, Sicilia, South European Russia, Sweden, Switzerland, Türkiye-in-Europe, Ukraine KazakhstanTranscaucasusWest SiberiaXinjiangAustriaBaltic StatesBelarusBelgiumBulgariaCentral European RussiaCzechia-SlovakiaDenmarkEast European RussiaFinlandFranceGermanyGreeceHungaryIrelandItalyNetherlandsNorth European RussiaNorthwest European RussiaNorwayNW. Balkan Pen.PolandRomaniaSiciliaSouth European RussiaSwedenSwitzerlandTürkiye-in-EuropeUkraine Sardegna
Native distribution of Glyceria maxima, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows. Regions too small to draw at this scale are marked with a dot.
RegionTDWG codeContinent
Austria AUT EUROPE
Baltic States BLT
Belarus BLR
Belgium BGM
Bulgaria BUL
Central European Russia RUC
Czechia-Slovakia CZE
Denmark DEN
East European Russia RUE
Finland FIN
France FRA
Germany GER
Great Britain GRB
Greece GRC
Hungary HUN
Ireland IRE
Italy ITA
Netherlands NET
North European Russia RUN
Northwest European Russia RUW
Norway NOR
NW. Balkan Pen. YUG
Poland POL
Romania ROM
Sardegna SAR
Sicilia SIC
South European Russia RUS
Sweden SWE
Switzerland SWI
Türkiye-in-Europe TUE
Ukraine UKR
Kazakhstan KAZ ASIA-TEMPERATE
Transcaucasus TCS
West Siberia WSB
Xinjiang CHX

Not drawn on the map: Great Britain. We hold no public-domain boundary for this region, so it is 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.

Flowering 36 in flower of 92 examined

Peak flowering in Feb. Each bar is the share of Glyceria maxima observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 36 of 92 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 4 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Where it actually grows measured, from 2,024 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -12.8 °C -6.4 °C 3.7 °C
Warmest month, mean daily high 19.1 °C 23.1 °C 26.1 °C
Annual rainfall 520 mm 664 mm 1,278 mm
Rainfall in the driest quarter 84 mm 111 mm 239 mm

It is found where winters bring hard frost. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 2,024 research-grade observations of Glyceria maxima 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. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

Also published as 30 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.

  • Catabrosa hydrophila Link
  • Exydra aquatica (L.) Endl.
  • Festuca aquatica (L.) Mutel
  • Glyceria altissima Garcke
  • Glyceria aquatica (L.) Wahlb.
  • Glyceria aquatica subsp. densiflora Waisb.
  • Glyceria aquatica subsp. umbrosa (Junge) Waisb.
  • Glyceria aquatica var. flavescens Peterm.
  • Glyceria aquatica var. laxa Hegi
  • Glyceria aquatica var. pallens Klett & Richt.
  • Glyceria aquatica var. scabra Peterm.
  • Glyceria maxima f. acuta (Peterm.) Soó
  • Glyceria maxima f. scabra (Peterm.) Soó
  • Glyceria maxima subsp. micrantha H.Scholz
  • Glyceria spectabilis Mert. & W.D.J.Koch
  • Glyceria spectabilis f. acuta Peterm.
  • Glyceria spectabilis var. acuta Peterm.
  • Glyceria spectabilis var. laevis Peterm.
  • Glyceria spectabilis var. scabra (Peterm.) Peterm.
  • Glyceria spectabilis var. vivipara Mert. & W.D.J.Koch
  • Heleochloa aquatica (L.) Fr.
  • Heleochloa aquatica (L.) Drejer
  • Hydrochloa aquatica (L.) Hartm.
  • Hydropoa spectabilis (Mert. & W.D.J.Koch) Dumort.

and 6 more.

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
  4. 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.