Example ⟳ +
An example collection, so you can see what this page does. Nothing added here is kept: leaving deletes it.

Cyperus cephalanthus Torr. & Hook.

Buttonbush flatsedge

Cyperaceae · Texas, Louisiana +4

Photographs not checked iNaturalist was skipped (not asked) when this page was built. Not asked, or not answered, is not "none": nothing here claims there is none. Why the site says it this way.
Add one to my plants
Sow seed
Habitat figures
Cold floor (1 night in 100)
-1.9°C
Record low -11.0 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
32°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,676mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
17–40DLI
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

Cyperus cephalanthus, commonly known as the buttonbush flatsedge, is a species of sedge that is native to southern parts of North America and South America.

Quoted from Wikipedia, "Cyperus cephalanthus", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (1,212 mm of 1,679 mm) takes 8 months, December to January and May to October. Mean temperature moves 16.6 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to April and June to July.

Rain

1,679 mm in the median year at the habitat, 1,212 mm of it December to January and May to October. Wettest month June at 184 mm, driest month April at 104 mm. Across the grid cells of the range the year's total runs 1,636 mm to 1,712 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,676 mm, is the year's rain at the top of the page; the 1,679 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: 17 to 40 mol/m²/day across the year (daily light integral, median year across the grid cells of the range, CHELSA).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -1.9 °C, the absolute minimum -11.0 °C, 337 frost nights in 44 years, 7.7 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 34.7 °C. Monthly means: the coldest month's mean nightly low 7.2 °C in January (across the grid cells of the range 7.0 °C to 7.9 °C), the warmest month's mean daily high 32.2 °C in August (median year across the grid cells of the range, CHELSA). Cold floor: -1.9 °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: 57 to 62% 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 -1 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 Cyperus cephalanthus through the yearWarmest months July and August, mean daily high 32 °C; coldest month January, mean nightly low 7.2 °C; 1,679 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°frost34.7° 99th-percentile day, NASA POWER-11.0° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200250mm rainDLI 17–40RH 57–62%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 20 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 °C17 / 16–1718 / 18–1822 / 22–2225 / 25–2629 / 29–3031 / 31–3232 / 32–3232 / 32–3230 / 30–3126 / 26–2622 / 21–2217 / 17–18
Night °C7 / 7–89 / 9–1012 / 12–1316 / 15–1620 / 20–2123 / 23–2424 / 24–2524 / 24–2522 / 22–2217 / 17–1812 / 12–138 / 8–9
Rain mm146 / 134–150128 / 111–132106 / 101–109104 / 100–109138 / 123–143184 / 176–205167 / 152–182145 / 139–154143 / 130–149146 / 143–150129 / 121–140143 / 135–149
DLI18 / 18–1923 / 23–2330 / 30–3037 / 37–3740 / 40–4039 / 39–3939 / 38–3936 / 36–3732 / 32–3227 / 27–2721 / 21–2117 / 17–17
RH %60 / 59–6059 / 59–605958 / 58–5960 / 59–6061 / 61–6262 / 62–6362 / 61–6259 / 59–6057 / 57–5858 / 58–5959
How this section is made
Each figure is the median across the 20 grid cells holding the 34 in-range records, 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 1199:1753 (30.025, -92.325). Over 44 years there: absolute minimum -11.0 °C, 1st-percentile night -1.9 °C, 99th-percentile day 34.7 °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 20 distinct grid cells holding 34 of the 34 in-range records; extremes and elevation at the typical cell 1199:1753 (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 30.00_-92.500, lapse-corrected -1 m at 6.5 °C/km. Elevation: ETOPO 2022, 4 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.
NativeTexas, Louisiana, Brazil South, Argentina Northeast, Paraguay, Uruguay · 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 marker30.198, -92.518 · in the densest population, 33 records (67% of those in range)
Kew's description“perennial or rhizomatous geophyte” · “subtropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 49 georeferenced records inside the native range; the climate across the range on the 34 of them placed to within 10 km; the map shows only the 25 openly licensed ones, which alone would put the marker 4 km away. 15 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 49 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Not checked. iNaturalist was skipped (not asked) when this page was built; GBIF's observation records with coordinates hold none. Not a statement that none exist.

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

Arnoglossum ovatum Arnoglossum ovatum Ovateleaf cacalia Photo: CC BY, Dan JohnsonViburnum scabrellum Viburnum scabrellum Southern Toothed Viburnum Photo: CC BY, Will KuhnIris × vinicolor Iris × vinicolor Vinicolor iris Photo: CC BY, Mike TilleyCyperus virens Cyperus virens Green flatsedge Photo: CC BY, Caroline KaneSymphyotrichum adnatum Symphyotrichum adnatum Scale-leaf aster Photo: CC0, author not statedHelianthus simulans Helianthus simulans Imitative sunflower Photo: CC BY, Daniel McClosky

Other Cyperus 73 in the reference

Cyperus acuminatus Cyperus acuminatus Taper-tip flatsedge Photo: CC BY, Frankie SimmonsCyperus aggregatus Cyperus aggregatus Inflatedscale flatsedge Photo: CC BY, Lucas CarboneCyperus alatus Cyperus alatus Cyperaceae Photo: CC0, author not statedCyperus albostriatus Cyperus albostriatus Dwarf umbrella-grass Photo: CC BY, Malte KrömerCyperus alternifolius Cyperus alternifolius Umbrella sedge Photo: CC0, author not statedCyperus aromaticus Cyperus aromaticus Navua sedge Photo: CC BY, Guillaume DelaitreCyperus articulatus Cyperus articulatus Jointed flatsedge Photo: CC BY, Cezanne SandersCyperus bipartitus Cyperus bipartitus Shining flatsedge Photo: CC BY, Nathan AaronCyperus brevifolius Cyperus brevifolius Globe Kyllinga Photo: CC0, author not statedCyperus byssaceus Cyperus byssaceus Cyperaceae Photo: CC BY, Agustina MedinaCyperus capitatus Cyperus capitatus Cyperaceae Photo: CC BY, Duarte FradeCyperus compressus Cyperus compressus Poorland flatsedge Photo: CC BY, Jerome Ko all 74 ›

Names & registers

Also known as Cyperus laetus var. cephalanthus; Cyperus rigens subsp. cephalanthus; Mariscus cephalanthus. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Cyperaceae
Described by
Torr. & Hook.
Native to
Texas, Louisiana, Brazil South +3
Wild records
49 in range · 25 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
Habitat climate climate answeredasked 2026-10-22
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 30.00_-92.500, lapse-corrected -1 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22
Wikipedia wikipedia answeredasked 2026-10-22
iNaturalist photographs, wild inat.photos.wild nothing to reportasked 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 nothing to reportasked 2026-10-22
Wikimedia Commons commons nothing to reportasked 2026-10-22
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 13 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…