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Borassus aethiopum; photograph (c) Philippe Hornus, some rights reserved (CC BY) CC BY(c) Philippe Hornus, some rights reserved (CC BY) · observed growing wild · 2018-05-09

Borassus aethiopum Mart.

Rhun Palm; African fan palm; Elephant Palm; Black-rum palm

Arecaceae · Benin, Burkina +29

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Borassus aethiopum, photograph (c) Philippe Hornus, some rights reserved (CC BY)Borassus aethiopum, photograph (c) Philippe Hornus, some rights reserved (CC BY)Borassus aethiopum, photograph (c) Philippe Hornus, some rights reserved (CC BY)Borassus aethiopum, photograph (c) Philippe Hornus, some rights reserved (CC BY)Borassus aethiopum, photograph (c) avocat, some rights reserved (CC BY)Borassus aethiopum, photograph (c) avocat, some rights reserved (CC BY) 46 photographs ›
Habitat figures
Cold floor (1 night in 100)
13.7°C
Record low 11.0 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
36°C
Feb and Mar at the habitat CHELSA
Rain a year (median across the range)
1,095mm
7 months of 25 mm or more in the median year CHELSA
Open-sky light
28–42DLI
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
Wet winters: the rain comes June to September, read as a winter growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Borassus aethiopum is a species of Borassus palm from Africa. In English, it is variously referred to as African fan palm, African palmyra palm, deleb palm, ron palm, toddy palm, black rhun palm, rônier palm (from the French). It is widespread across much of tropical Africa from Senegal to Ethiopia and south to northern South Africa, though it is largely absent from the forested areas of Central Africa and desert regions such as the Sahara and Namib. This palm also grows in northwest Madagascar and the Comoros.

Quoted from Wikipedia, "Borassus aethiopum", CC BY-SA 4.0.

About the genus · Borassus

Borassus is a genus of five species of fan palms, native to tropical regions of Africa, Asia, and Papua New Guinea.

Quoted from Wikipedia, "Borassus", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a winter growing season: 70% of the median year's rain (746 mm of 1,041 mm) falls in June to September, cooler than the year (wet-season mean 25.4 °C against a yearly mean of 26.8 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: December to March.

Rain

1,041 mm in the median year at the habitat, 746 mm of it June to September. Wettest month August at 233 mm, driest months (2 at 1 mm); 3 months under 5 mm. Across the grid cells of the range the year's total runs 778 mm to 1,321 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,095 mm, is the year's rain at the top of the page; the 1,041 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: 28 to 42 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 25, the highest 90th-percentile month 45).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is 13.7 °C, the absolute minimum 11.0 °C, no frost in 44 years (NASA POWER daily minima). Warmest: the 99th-percentile day is 39.6 °C. Monthly means: the coldest month's mean nightly low 19.3 °C in January (across the grid cells of the range 17.6 °C to 23.4 °C), the warmest month's mean daily high 36.3 °C in March (median year across the grid cells of the range, CHELSA). Cold floor: 13.7 °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: 38 to 67% 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 +19 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 Borassus aethiopum through the yearWarmest months February and March, mean daily high 36 °C; coldest month January, mean nightly low 19.3 °C; 1,041 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.10°15°20°25°30°35°40°45°39.6° 99th-percentile day, NASA POWER11.0° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200250300mm rainDLI 28–42RH 38–67%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 844 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 °C34 / 30–3536 / 31–3736 / 31–3935 / 30–4033 / 29–3831 / 28–3529 / 27–3129 / 27–3030 / 28–3131 / 29–3433 / 30–3633 / 30–35
Night °C19 / 18–2321 / 19–2423 / 21–2525 / 22–2624 / 22–2623 / 21–2522 / 20–2422 / 20–2322 / 20–2322 / 21–2421 / 19–2420 / 18–24
Rain mm1 / 0–253 / 0–4621 / 1–9962 / 14–129121 / 30–161154 / 56–200185 / 74–234233 / 49–287174 / 67–23578 / 23–1548 / 0–771 / 0–59
DLI38 / 34–4041 / 35–4342 / 35–4540 / 34–4437 / 31–4233 / 27–3930 / 25–3428 / 25–3532 / 27–3837 / 30–4038 / 32–4037 / 32–39
RH %38 / 33–6338 / 31–6347 / 32–6455 / 41–6560 / 51–6663 / 56–6866 / 59–6967 / 61–7067 / 60–6961 / 52–6849 / 38–6641 / 35–64
How this section is made
Each figure is the median across the 844 grid cells holding the 1394 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 1612:3659 (9.375, 2.975). Over 44 years there: absolute minimum 11.0 °C, 1st-percentile night 13.7 °C, 99th-percentile day 39.6 °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 844 distinct grid cells holding 1394 of the 1394 in-range records; extremes and elevation at the typical cell 1612:3659 (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 9.50_3.125, lapse-corrected +19 m at 6.5 °C/km. Elevation: ETOPO 2022, 391 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.
NativeBenin, Burkina, The Gambia, Ghana, Guinea-Bissau, Guinea, Ivory Coast, Mali, Nigeria, Niger, Senegal, Togo, Burundi, Central African Republic, Cameroon, Congo, Gulf of Guinea Is., Zaïre, Chad, Ethiopia, Sudan, Kenya, Tanzania, Uganda, Malawi, Mozambique, Zambia, Zimbabwe, Northern Provinces, Comoros, Madagascar · introduced: Trinidad-Tobago · 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 marker10.519, 1.288 · in the densest population, 1182 records (71% of those in range)
Kew's description“tree” · “seasonally dry tropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1668 georeferenced records inside the native range; the climate across the range on the 1394 of them placed to within 10 km; the map shows only the 1377 openly licensed ones, which alone would put the marker 13 km away. 5 records outside the WCVP native range not used. 274 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 inside the densest 2° block of the 1668 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Borassus aethiopum, photograph 1did not loadBorassus aethiopum, photograph 2did not loadBorassus aethiopum, photograph 3did not loadBorassus aethiopum, photograph 4did not loadBorassus aethiopum, photograph 5did not loadBorassus aethiopum, photograph 6did not load

Photographs: (c) Philippe Hornus, some rights reserved (CC BY) (4); (c) avocat, some rights reserved (CC BY) (2).

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

Annona senegalensis Annona senegalensis Wild custard-apple Photo: CC BY-SA, alanbedfordshawGardenia ternifolia Gardenia ternifolia Powderbark gardenia Photo: CC BY, keesgroenendijkStereospermum kunthianum Stereospermum kunthianum Pink-jacaranda Photo: CC BY, PhilippAfzelia africana Afzelia africana African mahogany Photo: CC BY, Zac PetersonCyphostemma flavicans Cyphostemma flavicans Vitaceae Photo: CC BY, Sunday Berlioz KAKPOParkia biglobosa Parkia biglobosa African locust-bean Photo: CC BY, Lucy Keith-Diagne

Other Borassus 3 in the reference

Borassus akeassii Borassus akeassii Arecaceae Photo: CC BY, Lucy Keith-DiagneBorassus flabellifer Borassus flabellifer Toddy palm Photo: CC BY-SA, Dinesh Valke Borassus madagascariensis Arecaceae

Names & registers

Also known as Borassus aethiopum var. bagamojense; Borassus aethiopum var. senegalense; Borassus deleb; Borassus flabellifer var. aethiopum; Borassus sambiranensis. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Arecaceae
Described by
Mart.
Native to
Benin, Burkina, The Gambia +28
Wild records
1668 in range · 1377 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 2026-10-21
GBIF species record gbif.species answeredasked 2026-10-21
GBIF synonyms gbif.synonyms answeredasked 2026-10-21
GBIF common names gbif.vernacular answeredasked 2026-10-21names fetched 2026-10-21
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; 5 records within 1 km of a botanic garden, herbarium or zoo left out (2 at a botanic garden or arboretum, 3 at a herbarium; Wikidata's list)
Habitat climate climate answeredasked 2026-10-21
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-21NASA POWER (MERRA-2) daily 1981–2024, cell 9.50_3.125, lapse-corrected +19 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-21
Wikipedia wikipedia answeredasked 2026-10-21
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 2026-10-21
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 80 datasets via GBIF.org; each carries its own licence.

Cultifolio

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