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Achyranthes aspera; photograph (c) 胡正恆(Jackson Hu), some rights reserved (CC BY) CC BY(c) 胡正恆(Jackson Hu), some rights reserved (CC BY) · observed growing wild · 2026-08-31

Achyranthes aspera L.

Devil's horsewhip; Chaff-flower; Man Better Man; Prickly chaff-flower

Amaranthaceae · Afghanistan, Iran +57

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Achyranthes aspera, photograph (c) 胡正恆(Jackson Hu), some rights reserved (CC BY)Achyranthes aspera, photograph (c) 胡正恆(Jackson Hu), some rights reserved (CC BY)Achyranthes aspera, photograph (c) 胡正恆(Jackson Hu), some rights reserved (CC BY)Achyranthes aspera, photograph author not stated, no rights reservedAchyranthes aspera, photograph author not stated, no rights reservedAchyranthes aspera, photograph author not stated, no rights reserved 80 photographs ›
Habitat figures
Cold floor (1 night in 100)
8.1°C
Record low 4.4 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
33°C
Dec at the habitat CHELSA
Rain a year (median across the range)
822mm
8 months of 25 mm or more in the median year CHELSA
Open-sky light
29–45DLI
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 summers: the rain comes December to March, read as a summer growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Achyranthes aspera (common names: chaff-flower, prickly chaff flower, devil's horsewhip, Sanskrit: अपामार्ग apāmārga) is a species of plant in the family Amaranthaceae. It is distributed throughout the tropical world. It can be found in many places growing as an introduced species and a common weed. It is an invasive species in some areas, including many Pacific Islands environments.

Quoted from Wikipedia, "Achyranthes aspera", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (514 mm of 731 mm) falls in December to March, warmer than the year (wet-season mean 27.8 °C against a yearly mean of 25.2 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: June to September.

Rain

731 mm in the median year at the habitat, 514 mm of it December to March. Wettest month February at 155 mm, driest month August at 6 mm. Across the grid cells of the range the year's total runs 437 mm to 1,894 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 822 mm, is the year's rain at the top of the page; the 731 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: 29 to 45 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 22, the highest 90th-percentile month 48).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is 8.1 °C, the absolute minimum 4.4 °C, no frost in 44 years (NASA POWER daily minima). Warmest: the 99th-percentile day is 42.9 °C. Monthly means: the coldest month's mean nightly low 14.4 °C in July (across the grid cells of the range 7.6 °C to 22.4 °C), the warmest month's mean daily high 32.8 °C in December (median year across the grid cells of the range, CHELSA). Cold floor: 8.1 °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: 51 to 60% 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 +62 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 Achyranthes aspera through the yearWarmest month December, mean daily high 33 °C; coldest month July, mean nightly low 14.4 °C; 731 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.0°10°20°30°40°50°42.9° 99th-percentile day, NASA POWER4.4° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400mm rainDLI 29–45RH 51–60%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 263 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 °C32 / 28–3632 / 28–3531 / 27–3430 / 25–3428 / 22–3226 / 19–3025 / 19–3027 / 21–3229 / 24–3531 / 26–3732 / 27–3833 / 28–37
Night °C24 / 20–2624 / 20–2623 / 19–2621 / 15–2519 / 12–2415 / 9–2314 / 8–2216 / 9–2319 / 12–2322 / 15–2523 / 18–2624 / 19–27
Rain mm150 / 63–340155 / 72–33395 / 41–27443 / 18–20130 / 7–17119 / 3–11414 / 2–896 / 0–989 / 2–15228 / 14–17568 / 36–160114 / 53–247
DLI40 / 33–4638 / 33–4238 / 33–4135 / 30–3831 / 25–3529 / 22–3330 / 24–3435 / 29–3841 / 34–4345 / 34–4744 / 31–4843 / 31–48
RH %59 / 50–6560 / 51–6658 / 47–6554 / 44–6554 / 45–6554 / 45–6452 / 43–6451 / 41–6351 / 40–6553 / 40–6555 / 43–6657 / 46–65

Records on both sides of the equator: the 220 cells at least 10° north of it have seasons six months apart and are left out, not combined into a year no place has. These figures are across the 263 cells that remain: the 224 at least 10° south and the 39 within 10° of the equator, which stay in either way.

How this section is made
Each figure is the median across the 263 grid cells on land that hold in-range records (272 records in those cells; 28 more cells hold records but no land by the elevation layer, so those records sit at sea and the cells are 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 2154:6184 (-17.725, 129.225). Over 44 years there: absolute minimum 4.4 °C, 1st-percentile night 8.1 °C, 99th-percentile day 42.9 °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 263 distinct grid cells holding 272 of the 589 in-range records (28 further cells with records at sea, by the elevation layer, left out) on the southern side of the equator (220 cells poleward of 10° north, 224 poleward of 10° south: the two sides' seasons are not combined, and cells within 10° of the equator stay in); extremes and elevation at the typical cell 2154:6184 (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 -17.50_129.375, lapse-corrected +62 m at 6.5 °C/km. Elevation: ETOPO 2022, 388 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.
NativeAfghanistan, Iran, China South-Central, Hainan, China Southeast, Kazan-retto, Nansei-shoto, Ogasawara-shoto, Taiwan, Assam, Bangladesh, East Himalaya, India, Laccadive Is., Maldives, Nepal, Pakistan, Sri Lanka, Andaman Is., Cambodia, Laos, Myanmar, Nicobar Is., South China Sea, Thailand, Vietnam, Borneo, Cocos (Keeling) I., Jawa, Lesser Sunda Is., Malaya, Maluku, Philippines, Sulawesi, Sumatera, Christmas I., Bismarck Archipelago, New Guinea, Solomon Is., Northern Territory, Queensland, Western Australia, Caroline Is., Marianas, Marshall Is., Florida, Mexico Southeast, Belize, Costa Rica, Guatemala, Cuba, Dominican Republic, Haiti, Leeward Is. AB Ant, Puerto Rico, Trinidad-Tobago, Windward Is., Venezuela, Colombia · introduced: Austria, Sardegna, Spain, Sicilia, Tunisia, Benin, Ghana, Liberia, Senegal, Cameroon, Gulf of Guinea Is., Rwanda, Zaïre, Chad, Ethiopia, Socotra, Somalia, Sudan, Kenya, Tanzania, Uganda, Mozambique, Zimbabwe, Namibia, KwaZulu-Natal, St.Helena, Comoros, Mauritius, Mozambique Channel Is., Madagascar, Réunion, Rodrigues, Seychelles, Lebanon-Syria, Palestine, Gulf States, Oman, Saudi Arabia, Yemen, Japan, Norfolk Is., Kermadec Is., New Zealand North, Fiji, Gilbert Is., Niue, New Caledonia, Samoa, Tokelau-Manihiki, Tonga, Vanuatu, Wallis-Futuna Is., Cook Is., Line Is., Marquesas, Pitcairn Is., Society Is., Tuamotu, Tubuai Is., Hawaii, Texas, Alabama, Louisiana, Maryland, South Carolina, Mexico Central, Mexico Northeast, Mexico Gulf, Mexico Northwest, Mexico Southwest, El Salvador, Honduras, Nicaragua, Panama, Aruba, Bahamas, Jamaica, Netherlands Antilles, Southwest Caribbean, Turks-Caicos Is., Venezuelan Antilles, French Guiana, Guyana, Surinam, Bolivia, Galápagos, Peru, Brazil West-Central, Brazil Northeast, Brazil Southeast, Brazil North · 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 marker23.508, 120.528 · in the densest population, 105 records (12% of those in range)
Kew's description“annual or subshrub” · “subtropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 879 georeferenced records inside the native range; the climate across the range on the 272 of them in the land cells it reads, of 589 placed to within 10 km; the map shows only the 589 openly licensed ones, which alone would put the marker 24 km away. 820 records outside the WCVP native range not used. 290 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 879 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Achyranthes aspera, photograph 1did not loadAchyranthes aspera, photograph 2did not loadAchyranthes aspera, photograph 3did not loadAchyranthes aspera, photograph 4did not loadAchyranthes aspera, photograph 5did not loadAchyranthes aspera, photograph 6did not load

Photographs: (c) 胡正恆(Jackson Hu), some rights reserved (CC BY) (3); author not stated, no rights reserved · CC0 (3).

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

Glinus oppositifolius Glinus oppositifolius Slender carpetweed Photo: CC BY, Raja Sekhar ChimiralaSesbania cannabina Sesbania cannabina Sesbania pea Photo: CC BY, 祐Pontederia cyanea Pontederia cyanea Blue Hyacinth Photo: CC BY, Joachim BlatchlyRhynchosia minima Rhynchosia minima Least snout bean Photo: CC BY, Kelsey LowDiospyros humilis Diospyros humilis Australian Ebony Photo: CC BY, Tony van KampenBlumea axillaris Blumea axillaris Asteraceae Photo: CC BY-SA, Tony Rebelo

Other Achyranthes 3 in the reference

Achyranthes bidentata Achyranthes bidentata Ox Knee Photo: CC BY, Emily Summerbell Achyranthes sandwicensis Amaranthaceae Achyranthes splendens Achyranthes splendens Maui chaff flower Photo: CC0, author not stated

Names & registers

Also known as Achyranthes acuminata; Achyranthes argentea var. villosior; Achyranthes aspera f. nigrescens; Achyranthes aspera f. robustiformis; Achyranthes aspera f. subgrandifolia and 28 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Amaranthaceae
Described by
L.
Native to
Afghanistan, Iran, China South-Central +56
Wild records
879 in range · 589 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; 33 records within 1 km of a botanic garden, herbarium or zoo left out (20 at a botanic garden or arboretum, 2 at a herbarium, 11 at a zoo; 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 -17.50_129.375, lapse-corrected +62 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 226 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…