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Scirpus georgianus; photograph (c) Logan Young, some rights reserved (CC BY) CC BY(c) Logan Young, some rights reserved (CC BY) · observed growing wild · 2025-08-22

Scirpus georgianus R.M.Harper

Georgia bulrush; Bristleless dark-green bulrush

Cyperaceae · Ontario, Prince Edward I. +30

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Scirpus georgianus, photograph author not stated, no rights reservedScirpus georgianus, photograph author not stated, no rights reservedScirpus georgianus, photograph author not stated, no rights reservedScirpus georgianus, photograph author not stated, no rights reservedScirpus georgianus, photograph author not stated, no rights reservedScirpus georgianus, photograph author not stated, no rights reserved 73 photographs ›
Habitat figures
Cold floor (1 night in 100)
-10.7°C
Record low -17.1 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
30°C
Jul at the habitat CHELSA
Rain a year (median across the range)
1,193mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
12–40DLI
Lowest to highest month (DLI) CHELSA
The year in your months, northern hemisphere
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
Rain spread: 70% of the median year's rain takes 8 months, so no short rainy season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Scirpus georgianus, or Georgia bulrush, is a flowering plant in the family Cyperaceae that grows in much of the eastern half of North America. Its habitat is wet marshy field areas prone to seasonal flooding. It was described by Roland McMillan Harper.

Quoted from Wikipedia, "Scirpus georgianus", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (843 mm of 1,189 mm) takes 8 months, March to October. Mean temperature moves 24.8 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: September to April.

Rain

1,189 mm in the median year at the habitat, 843 mm of it March to October. Wettest month May at 116 mm, driest month February at 76 mm. Across the grid cells of the range the year's total runs 1,042 mm to 1,365 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,193 mm, is the year's rain at the top of the page; the 1,189 mm here is the median year's, the twelve monthly medians added, which the rain rule reads. Habitat calendar, northern hemisphere; median year across the grid cells of the range, CHELSA.

Light

Open sky over the habitat: 12 to 40 mol/m²/day across the year (daily light integral, median year across the grid cells of the range, CHELSA; the lowest 10th-percentile month across the cells is 10, the highest 90th-percentile month 42).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -10.7 °C, the absolute minimum -17.1 °C, 3,366 frost nights in 44 years, 76.5 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 30.5 °C. Monthly means: the coldest month's mean nightly low -3.3 °C in January (across the grid cells of the range -7.0 °C to 1.0 °C), the warmest month's mean daily high 29.9 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -10.7 °C, which is the 1st-percentile night over 44 years at a typical spot in the range (NASA POWER).

Humidity

Relative humidity at the habitat: 55 to 59% across the year (monthly means, median year across the grid cells of the range, CHELSA). A figure about the air, saying nothing about how the plant takes water.

How this section is made

Each card states this species' habitat figures with their sources, and what two fixed rules read from them; nothing here says what the plant does, wants or tolerates. The rules · the terms.

Seasons. Read from the median year of CHELSA monthly rainfall and mean temperature across the grid cells of the range: the rain rule takes the smallest set of months carrying 70% of the rain and calls it winter when its mean is more than half a degree below the year's, summer when more than that above, and neither in between; the temperature rule, used only under 120 mm, names the cooler six months when they are at least a degree cooler than the other six. Months are shifted for the other hemisphere only where the temperature curve moves 4 °C or more and the habitat lies 10° or more from the equator. A reading of the curves, not an observation of the plant.

Rain. CHELSA monthly precipitation, median year across the grid cells of the range. The rain that falls where the species is recorded; nothing about how the plant takes water.

Light. CHELSA shortwave radiation at each envelope cell, a daily-mean flux taken to a daily total and converted at 2.07 mol of PAR per MJ. The sky over the habitat, measured; what reaches a plant under a rock, a shrub or a shade cloth is not.

Temperature. NASA POWER daily minima and maxima over 44 years at a typical spot in the range, lapse-corrected -12 m to its elevation; CHELSA monthly means, median year across the grid cells of the range. The cold floor is the 1st-percentile night named in its sentence. Not a measured survival limit for any plant in a pot.

Humidity. CHELSA relative humidity, median year across the grid cells of the range.

Climate across the habitat

Habitat months, northern hemisphere

Habitat climate of Scirpus georgianus through the yearWarmest month July, mean daily high 30 °C; coldest month January, mean nightly low -3.3 °C; 1,189 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA; the extremes at the edge from NASA POWER. Habitat months, northern hemisphere.-20°-10°0°10°20°30°40°frost30.5° 99th-percentile day, NASA POWER-17.1° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200mm rainDLI 12–40RH 55–59%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 561 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low extremes over 44 years at a typical spot in the range, from NASA POWER, marked at the edge, in no month DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C5 / 1–107 / 3–1313 / 8–1719 / 14–2223 / 19–2628 / 24–3030 / 27–3229 / 26–3226 / 22–2819 / 16–2213 / 10–167 / 3–11
Night °C-3 / -7–1-2 / -6–32 / -2–68 / 4–1113 / 9–1618 / 15–2021 / 17–2320 / 17–2216 / 13–1810 / 7–135 / 2–8-1 / -4–3
Rain mm83 / 43–10276 / 54–104101 / 77–120105 / 85–124116 / 96–153110 / 98–145115 / 97–13499 / 80–119102 / 80–12295 / 80–11894 / 76–12193 / 62–123
DLI14 / 13–1720 / 18–2127 / 25–2833 / 32–3637 / 36–3940 / 39–4139 / 38–4234 / 33–3829 / 27–3122 / 20–2415 / 13–1812 / 10–15
RH %58 / 56–6057 / 55–5956 / 55–5755 / 54–5757 / 56–5958 / 57–6058 / 57–6159 / 56–6158 / 56–6057 / 55–5958 / 57–5958 / 57–61
How this section is made
Each figure is the median across the 561 grid cells on land that hold in-range records (629 records in those cells; 1 more cell holds records but no land by the elevation layer, so those records sit at sea and the cell is left out), with the 10th–90th percentile span across those cells after the slash where it differs. A dash is a month one or more of those cells has no figure for in the grid (a variable CHELSA does not carry there), so no median is taken rather than one over fewer cells. Extremes and elevation were read at a typical spot in the range, cell 975:2138 (41.225, -73.075). Over 44 years there: absolute minimum -17.1 °C, 1st-percentile night -10.7 °C, 99th-percentile day 30.5 °C. Normals: CHELSA V2.1 1981–2010 climatology, 0.05° cells (each the mean of ~36 1 km pixels). Across the range: median and 10th–90th percentile of each month across the 561 distinct grid cells holding 629 of the 630 in-range records (1 further cell with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 975:2138 (its coldest month's mean nightly low nearest the median across cells); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 41.00_-73.125, lapse-corrected -12 m at 6.5 °C/km. Elevation: ETOPO 2022, 19 m (cell mean).

Natural habitat

Native range as published by WCVP; the marker is where the records are densest and decides nothing: the climate was read across the cells of the in-range records placed well enough to read one, not at the marker.
Openly licensed records inside the range, framed on where they fall.
NativeOntario, Prince Edward I., Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, Wisconsin, Connecticut, Indiana, Maine, Massachusetts, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode I., Vermont, West Virginia, Texas, Alabama, Arkansas, Georgia, Kentucky, Louisiana, Maryland, North Carolina, South Carolina, Tennessee, Virginia · introduced: Austria, Belgium, Germany, Netherlands, Poland, Yugoslavia, Japan, New Zealand South · regions are the level-3 units of the World Geographical Scheme for Recording Plant Distributions, as Kew's World Checklist records ranges, some under historical names such as Yugoslavia or Czechoslovakia (how).
Map marker39.212, -75.981 · in the densest population, 234 records (23% of those in range)
Kew's description“perennial” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1006 georeferenced records inside the native range; the climate across the range on the 629 of them in the land cells it reads, of 630 placed to within 10 km; the map shows only the 499 openly licensed ones, which alone would put the marker 94 km away. 166 records outside the WCVP native range not used. 376 in-range records are placed to worse than 10 km, or with no stated accuracy (admitted only as a person's observation to three decimals), and stay on the map but off the climate.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population of the 1006 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Scirpus georgianus, photograph 1did not loadScirpus georgianus, photograph 2did not loadScirpus georgianus, photograph 3did not loadScirpus georgianus, photograph 4did not loadScirpus georgianus, photograph 5did not loadScirpus georgianus, photograph 6did not load

Photographs: author not stated, no rights reserved · CC0 (6).

Similar habitat climate The 6 nearest by mean daily high, mean nightly low and rain, month by month. How.

Desmodium canescens Desmodium canescens Hoary tick-trefoil Photo: CC BY, Samuel BucknerCorydalis flavula Corydalis flavula Yellow corydalis Photo: CC BY-SA, Judith BushAsimina triloba Asimina triloba Pawpaw Photo: CC0, author not statedSisyrinchium angustifolium Sisyrinchium angustifolium Narrow-leaf blue-eyed-grass Photo: CC BY, Matt PelikanPackera obovata Packera obovata Round-leaf ragwort Photo: CC0, author not statedHypericum prolificum Hypericum prolificum Shrubby St. John's-wort Photo: CC BY-SA, Douglas Goldman

Other Scirpus 9 in the reference

Scirpus atrovirens Scirpus atrovirens Dark-green bulrush Photo: CC BY, treelogicalScirpus cyperinus Scirpus cyperinus Woolgrass Photo: CC0, author not statedScirpus microcarpus Scirpus microcarpus Panicled bulrush Photo: CC0, author not statedScirpus pendulus Scirpus pendulus Pendulous bulrush Photo: CC BY-SA, Henry "Nick" RobertsonScirpus polyphyllus Scirpus polyphyllus Leafy bulrush Photo: CC BY, Summit Metro ParksScirpus radicans Scirpus radicans Creeping Club-rush Photo: CC BY, Марина ДавлетшинаScirpus sylvaticus Scirpus sylvaticus Wood club-rush Photo: CC BY, Natalia KazakovaScirpus ternatanus Scirpus ternatanus Cyperaceae Photo: CC BY, 如此甚好Scirpus wichurae Scirpus wichurae Long pine-cone bulrush Photo: CC BY, WATANABE Hitoshi 渡辺仁

Names & registers

Also known as Scirpus atrovirens f. georgianus; Scirpus atrovirens subsp. georgianus; Scirpus atrovirens var. georgianus. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Cyperaceae
Described by
R.M.Harper
Native to
Ontario, Prince Edward I., Illinois +29
Wild records
1006 in range · 499 open

Every figure here is derived from public data by a stated rule and names its source; nothing about this species is written for its page by a person or by AI, apart from the marked, credited quotations. How →

Where this page came from built 2026-10-22
GBIF species record gbif.species answeredasked 2026-10-22
GBIF synonyms gbif.synonyms answeredasked 2026-10-22
GBIF common names gbif.vernacular answeredasked 2026-10-22names fetched 2026-10-22
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 22 records within 1 km of a botanic garden, herbarium or zoo left out (12 at a botanic garden or arboretum, 10 at a zoo; Wikidata's list)
Habitat climate climate answeredasked 2026-10-22
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 41.00_-73.125, lapse-corrected -12 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22
Wikipedia wikipedia answeredasked 2026-10-22
iNaturalist photographs, wild inat.photos.wild answeredasked 2026-10-22from iNaturalist's open data of 2026-09-27: research-grade observations with an open-licence photograph, the 24 whose photographs iNaturalist received last (the open data holds no votes); filled 2026-10-22
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media answeredasked 2026-10-22none of the photographs on this page is credited to GBIF: those shown are other sources', and GBIF's were the same photographs or were set aside by the photograph rules
OpenAlex papers openalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshot

Every source is recorded as having answered, reported nothing, refused, failed, not been asked, or answered twice where one answer is taken (“not taken: two items answered”), and, for a source asked when this page was built, when: the figures are as the source held them that day; a source read from a file (Kew's World Checklist, a GBIF download) says "as of" the file's day instead; a row carried from an earlier build of the page names that build instead. Only “nothing to report” is ever shown as an absence. Records came from 122 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…