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Alternanthera caracasana; photograph (c) Aiver, some rights reserved (CC BY) CC BY(c) Aiver, some rights reserved (CC BY) · observed growing wild · 2026-04-25

Alternanthera caracasana Kunth

Washerwoman; Mat chaff-flower; Paperthorn; Khakiweed

Amaranthaceae · Mexico Central, Mexico Northeast +22

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Alternanthera caracasana, photograph author not stated, no rights reservedAlternanthera caracasana, photograph (c) CK2AZ, some rights reserved (CC BY)Alternanthera caracasana, photograph (c) CK2AZ, some rights reserved (CC BY)Alternanthera caracasana, photograph author not stated, no rights reservedAlternanthera caracasana, photograph (c) Samantha Knight, some rights reserved (CC BY)Alternanthera caracasana, photograph (c) Samantha Knight, some rights reserved (CC BY) 57 photographs ›
Habitat figures
Cold floor (1 night in 100)
-2.0°C
Record low -9.3 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
27°C
May and Jun at the habitat CHELSA
Rain a year (median across the range)
771mm
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 May to October, 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

Alternanthera caracasana is a species of flowering plant in the family Amaranthaceae known by the common names khakiweed, washerwoman and mat chaff flower. It is native to Central and South America but is well-known elsewhere as a noxious weed. It is naturalized in some areas and invasive in others and can be found across the southern half of the United States, Australia (where many people are unaware it is not native), Spain and parts of Africa. The plant has long, prostrate stems covered in small leaves which vary in shape from diamond to rounded. More on Wikipedia ›

Quoted from Wikipedia, "Alternanthera caracasana", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (499 mm of 631 mm) falls in May to October, warmer than the year (wet-season mean 19.8 °C against a yearly mean of 17.4 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to April.

Rain

631 mm in the median year at the habitat, 499 mm of it May to October. Wettest month June at 103 mm, driest month March at 17 mm. Across the grid cells of the range the year's total runs 450 mm to 1,228 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 771 mm, is the year's rain at the top of the page; the 631 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 18, the highest 90th-percentile month 50).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -2.0 °C, the absolute minimum -9.3 °C, 479 frost nights in 44 years, 10.9 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 35.7 °C. Monthly means: the coldest month's mean nightly low 6.5 °C in January (across the grid cells of the range 3.1 °C to 17.1 °C), the warmest month's mean daily high 27.2 °C in May (median year across the grid cells of the range, CHELSA). Cold floor: -2.0 °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: 52 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 +126 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 Alternanthera caracasana through the yearWarmest months May and June, mean daily high 27 °C; coldest month January, mean nightly low 6.5 °C; 631 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°frost35.7° 99th-percentile day, NASA POWER-9.3° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200mm rainDLI 29–45RH 52–60%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 392 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 °C19 / 16–2521 / 17–2623 / 19–2826 / 20–2927 / 20–3127 / 19–3325 / 19–3425 / 19–3524 / 19–3123 / 19–2821 / 18–2719 / 16–26
Night °C7 / 3–178 / 4–1710 / 5–1712 / 8–1714 / 9–2015 / 10–2315 / 9–2415 / 10–2514 / 10–2212 / 9–1910 / 6–177 / 4–17
Rain mm26 / 10–9719 / 9–9617 / 5–11530 / 8–8559 / 12–110103 / 16–16797 / 36–20093 / 36–19887 / 47–18360 / 31–13621 / 9–11519 / 5–104
DLI30 / 19–3435 / 23–3941 / 29–4545 / 35–4843 / 35–5041 / 34–4741 / 34–4440 / 35–4235 / 32–3933 / 26–3631 / 20–3429 / 18–32
RH %55 / 49–6454 / 48–6352 / 45–6353 / 43–6355 / 45–6359 / 50–6459 / 52–6559 / 53–6560 / 54–6658 / 52–6657 / 49–6455 / 49–63
How this section is made
Each figure is the median across the 392 grid cells on land that hold in-range records (538 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 1292:1579 (25.375, -101.025). Over 44 years there: absolute minimum -9.3 °C, 1st-percentile night -2.0 °C, 99th-percentile day 35.7 °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 392 distinct grid cells holding 538 of the 539 in-range records (1 further cell with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 1292:1579 (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 25.50_-101.250, lapse-corrected +126 m at 6.5 °C/km. Elevation: ETOPO 2022, 1738 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.
NativeMexico Central, Mexico Northeast, Mexico Gulf, Mexico Northwest, Mexico Southwest, Mexico Southeast, Costa Rica, Honduras, Nicaragua, Cuba, Dominican Republic, Haiti, Jamaica, Leeward Is. AB Ant, Puerto Rico, Trinidad-Tobago, Windward Is., Venezuela, Bolivia, Colombia, Ecuador, Peru, Argentina Northeast, Argentina Northwest · introduced: Spain, Azores, Canary Is., Cape Verde, Madeira, Rwanda, Zaïre, Eritrea, Kenya, Tanzania, Uganda, Malawi, Zambia, Zimbabwe, Botswana, Free State, Northern Provinces, New Caledonia, Hawaii, Oklahoma, Arizona, California, New Mexico, Texas, Alabama, Arkansas, Florida, Georgia, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Galápagos · 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 marker19.443, -98.943 · in the densest population, 370 records (49% of those in range)
Kew's description“subshrub” · “seasonally dry tropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 753 georeferenced records inside the native range; the climate across the range on the 538 of them in the land cells it reads, of 539 placed to within 10 km; the map shows only the 424 openly licensed ones, which alone would put the marker 1172 km away. 692 records outside the WCVP native range not used. 214 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 4° block of the 753 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Alternanthera caracasana, photograph 1did not loadAlternanthera caracasana, photograph 2did not loadAlternanthera caracasana, photograph 3did not loadAlternanthera caracasana, photograph 4did not loadAlternanthera caracasana, photograph 5did not loadAlternanthera caracasana, photograph 6did not load

Photographs: author not stated, no rights reserved · CC0 (2); (c) CK2AZ, some rights reserved (CC BY) (2); (c) Samantha Knight, 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.

Coryphantha georgii Coryphantha georgii Cactaceae Photo: CC BY, Alejandro Gómez MayaYucca potosina Yucca potosina Potosi palm Photo: CC BY-SA, Juan Cruzado CortésEcheveria lyonsii Echeveria lyonsii Crassulaceae Photo: CC BY, Claudio Cantú MuñizPinguicula ehlersiae Pinguicula ehlersiae Lentibulariaceae Photo: CC BY-SA, jackyKSedum palmeri Sedum palmeri Palmer's Sedum Photo: CC BY, Cody HinchliffSedum gypsophilum Sedum gypsophilum Crassulaceae Photo: CC BY, Alejandro Gómez Maya

Other Alternanthera 19 in the reference

Alternanthera aquatica Alternanthera aquatica Hassler's alternanthera Photo: CC BY-SA, Krzysztof Ziarnek, KenraizAlternanthera bettzickiana Alternanthera bettzickiana Calico-plant Photo: CC BY, Silvia TenAlternanthera brasiliana Alternanthera brasiliana Brazilian joyweed Photo: CC BY, Richard LittauerAlternanthera denticulata Alternanthera denticulata Lesser joyweed Photo: CC BY-SA, Greg TasneyAlternanthera echinocephala Alternanthera echinocephala Sea-urchin joyweed Photo: CC BY, Mike BradyAlternanthera ficoidea Alternanthera ficoidea Amaranthaceae Photo: CC BY, Andrew AllenAlternanthera filifolia Alternanthera filifolia Three-leafed chaff flower Photo: CC BY, Jacob SaucierAlternanthera flavescens Alternanthera flavescens Yellow joyweed Photo: CC BY, Kenzie Anderson-BellAlternanthera flavicoma Alternanthera flavicoma Amaranthaceae Photo: CC BY, Andrea GantzerAlternanthera halimifolia Alternanthera halimifolia Hairy joyweed Photo: CC BY, Ellky Arteta ParedesAlternanthera nahui Alternanthera nahui Nahui Photo: CC BY, William HarlandAlternanthera paronychioides Alternanthera paronychioides Smooth joyweed Photo: CC BY, Adam Kamal all 20 ›

Names & registers

Also known as Achyranthes peploides; Alternanthera achyrantha var. dasyantha; Alternanthera achyrantha var. parvifolia; Alternanthera macrorhiza; Alternanthera parvifolia and 5 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Amaranthaceae
Described by
Kunth
Native to
Mexico Central, Mexico Northeast, Mexico Gulf +21
Wild records
753 in range · 424 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; 119 records within 1 km of a botanic garden, herbarium or zoo left out (73 at a botanic garden or arboretum, 18 at a herbarium, 28 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 25.50_-101.250, lapse-corrected +126 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 124 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…