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Amaranthus hybridus; photograph (c) zebedeugalinha, some rights reserved (CC BY) CC BY(c) zebedeugalinha, some rights reserved (CC BY) · observed growing wild · 2026-09-12

Amaranthus hybridus L.

Green amaranth; Smooth amaranth; Green pigweed; Slim amaranth

Amaranthaceae · Ontario, Massachusetts +43

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Amaranthus hybridus, photograph (c) Anne Parker, some rights reserved (CC BY)Amaranthus hybridus, photograph (c) Anne Parker, some rights reserved (CC BY)Amaranthus hybridus, photograph (c) Anne Parker, some rights reserved (CC BY)Amaranthus hybridus, photograph (c) Anne Parker, some rights reserved (CC BY)Amaranthus hybridus, photograph (c) Anne Parker, some rights reserved (CC BY)Amaranthus hybridus, photograph (c) Anne Parker, some rights reserved (CC BY) 67 photographs ›
Habitat figures
Cold floor (1 night in 100)
-0.2°C
Record low -8.5 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
27°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,201mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
25–40DLI
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
Wet summers: the rain comes May to November, 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

Amaranthus hybridus, commonly called green amaranth, slim amaranth, smooth amaranth, smooth pigweed, or red amaranth, is a species of annual flowering plant. It is a weedy species found now over much of North America and introduced into Europe and Eurasia.

Quoted from Wikipedia, "Amaranthus hybridus", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (751 mm of 1,034 mm) falls in May to November, warmer than the year (wet-season mean 19.4 °C against a yearly mean of 17.7 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to May.

Rain

1,034 mm in the median year at the habitat, 751 mm of it May to November. Wettest month July at 129 mm, driest months (2 at 51 mm). Across the grid cells of the range the year's total runs 496 mm to 1,970 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,201 mm, is the year's rain at the top of the page; the 1,034 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: 25 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 11, the highest 90th-percentile month 47).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -0.2 °C, the absolute minimum -8.5 °C, 179 frost nights in 44 years, 4.1 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 36.6 °C. Monthly means: the coldest month's mean nightly low 6.8 °C in January (across the grid cells of the range -5.6 °C to 18.0 °C), the warmest month's mean daily high 26.8 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -0.2 °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: 56 to 63% 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 -32 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 Amaranthus hybridus through the yearWarmest months July and August, mean daily high 27 °C; coldest month January, mean nightly low 6.8 °C; 1,034 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°0°10°20°30°40°frost36.6° 99th-percentile day, NASA POWER-8.5° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400mm rainDLI 25–40RH 56–63%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 86 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 / 3–2721 / 5–2823 / 10–3025 / 16–3126 / 19–3226 / 20–3127 / 19–3027 / 19–3023 / 19–2921 / 17–2820 / 11–2719 / 5–27
Night °C7 / -6–188 / -5–189 / -1–2011 / 5–2213 / 10–2316 / 11–2318 / 10–2317 / 10–2314 / 10–2311 / 8–229 / 3–208 / -3–19
Rain mm51 / 11–9656 / 10–10551 / 7–11566 / 13–122100 / 38–129116 / 60–323129 / 62–325111 / 56–301115 / 75–333104 / 39–19776 / 11–13859 / 6–116
DLI26 / 13–3330 / 19–3835 / 26–4439 / 30–4740 / 31–4639 / 31–4138 / 30–4135 / 31–4032 / 27–3630 / 20–3427 / 14–3325 / 11–32
RH %58 / 51–6856 / 50–6756 / 47–6556 / 47–6557 / 51–6660 / 57–6861 / 57–6961 / 58–6963 / 58–7062 / 57–6859 / 54–6858 / 52–68
How this section is made
Each figure is the median across the 86 grid cells holding the 88 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 1311:1552 (24.425, -102.375). Over 44 years there: absolute minimum -8.5 °C, 1st-percentile night -0.2 °C, 99th-percentile day 36.6 °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 86 distinct grid cells holding 88 of the 88 in-range records; extremes and elevation at the typical cell 1311:1552 (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 24.50_-102.500, lapse-corrected -32 m at 6.5 °C/km. Elevation: ETOPO 2022, 1676 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, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode I., Vermont, Texas, Alabama, Arkansas, Delaware, Florida, Georgia, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, Mexico Central, Mexico Northeast, Mexico Gulf, Mexico Southwest, Mexico Southeast, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama, Venezuela, Bolivia, Colombia, Ecuador, Galápagos, Peru, Brazil West-Central, Argentina Northeast, Argentina South, Argentina Northwest, Paraguay, Uruguay · introduced: Denmark, Finland, Great Britain, Ireland, Norway, Sweden, Austria, Belgium, Czechoslovakia, Germany, Hungary, Poland, Switzerland, Baleares, Corse, France, Portugal, Sardegna, Spain, Albania, Bulgaria, Greece, Italy, Kriti, Romania, Sicilia, Yugoslavia, Krym, North European Russia, Algeria, Egypt, Libya, Morocco, Tunisia, Azores, Canary Is., Cape Verde, Madeira, Benin, Burkina, Gambia, The, Ghana, Guinea, Ivory Coast, Liberia, Mali, Nigeria, Senegal, Sierra Leone, Togo, Central African Republic, Cameroon, Congo, Gabon, Gulf of Guinea Is., Rwanda, Zaïre, Chad, Eritrea, Ethiopia, Sudan, Kenya, Tanzania, Uganda, Angola, Malawi, Zambia, Zimbabwe, Botswana, Cape Provinces, Lesotho, Namibia, KwaZulu-Natal, Free State, Swaziland, Northern Provinces, Comoros, Mauritius, Réunion, Primorye, North Caucasus, Transcaucasus, Afghanistan, Cyprus, East Aegean Is., Iran, Iraq, Lebanon-Syria, Sinai, Turkey, Gulf States, Oman, Saudi Arabia, Yemen, China South-Central, China North-Central, China Southeast, Japan, Korea, Nansei-shoto, Assam, East Himalaya, India, Nepal, Pakistan, Sri Lanka, West Himalaya, Cambodia, Laos, Myanmar, Thailand, Vietnam, New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia, Hawaii, British Columbia, Manitoba, Nova Scotia, Québec, Colorado, Idaho, Montana, Oregon, Washington, Illinois, Iowa, Kansas, Minnesota, Missouri, North Dakota, Nebraska, Oklahoma, South Dakota, Wisconsin, Connecticut, Indiana, Maine, Michigan, Ohio, West Virginia, Arizona, California, Nevada, New Mexico, Kentucky, District of Columbia, Mexico Northwest, Bahamas, Bermuda, Cuba, Dominican Republic, Leeward Is. AB Ant, Brazil Northeast, Brazil Southeast, Brazil North, Brazil South, Chile Central, Chile North, Chile South, Juan Fernández Is., Tristan da Cunha · 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 marker19.546, -96.862 · in the densest population, 51 records (35% of those in range)
Kew's description“annual” · “seasonally dry tropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 146 georeferenced records inside the native range; the climate across the range on the 88 of them placed to within 10 km; the map shows only the 113 openly licensed ones, which alone would put the marker 29 km away. 1615 records outside the WCVP native range not used. 58 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 146 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Amaranthus hybridus, photograph 1did not loadAmaranthus hybridus, photograph 2did not loadAmaranthus hybridus, photograph 3did not loadAmaranthus hybridus, photograph 4did not loadAmaranthus hybridus, photograph 5did not loadAmaranthus hybridus, photograph 6did not load

Photographs: (c) Anne Parker, some rights reserved (CC BY) (6).

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

Sporobolus indicus Sporobolus indicus Smut grass Photo: CC0, author not statedSalvia compsostachys Salvia compsostachys Lamiaceae Photo: CC BY, Erick Vélez SánchezMagnolia tamaulipana Magnolia tamaulipana Magnoliaceae Photo: CC BY, Annika LindqvistPinguicula cyclosecta Pinguicula cyclosecta Lentibulariaceae Photo: CC BY, Claudio Cantú MuñizEcheveria shaviana Echeveria shaviana Mexican fire cracker Photo: CC BY, Claudio Cantú MuñizQuercus canbyi Quercus canbyi Fagaceae Photo: CC BY-SA, Rogelio Reyna-Hernández

Other Amaranthus 23 in the reference

Amaranthus albus Amaranthus albus White pigweed Photo: CC0, author not statedAmaranthus australis Amaranthus australis Southern amaranth Photo: CC0, author not statedAmaranthus blitoides Amaranthus blitoides Prostrate pigweed Photo: CC BY, Tatyana SovaAmaranthus blitum Amaranthus blitum Purple amaranth Photo: CC BY, Jason GrantAmaranthus caudatus Amaranthus caudatus Love-lies-bleeding Photo: CC BY, Evgenij SamarinAmaranthus cruentus Amaranthus cruentus Purple amaranth Photo: CC0, author not statedAmaranthus deflexus Amaranthus deflexus Perennial pigweed Photo: CC BY-SA, Pere BarnolaAmaranthus dubius Amaranthus dubius Spleen Amaranth Photo: CC BY, scallionsAmaranthus fimbriatus Amaranthus fimbriatus Amaranthaceae Photo: CC BY, Jo Roberts Amaranthus floridanus Florida amaranth Amaranthus graecizans Amaranthus graecizans Mediterranean amaranth Photo: CC BY, Michael AndresekAmaranthus hypochondriacus Amaranthus hypochondriacus Prince's-feather Photo: CC BY, Thomas Gyselinck all 24 ›

Names & registers

Also known as Amaranthus aureus; Amaranthus batalleri; Amaranthus bellardii; Amaranthus catechu; Amaranthus chlorostachys var. debilis and 46 more. (GBIF Backbone)

Under another author Amaranthus caudatus Baker & Clarke is an older name of this species, not Amaranthus caudatus, a species of the reference. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Amaranthaceae
Described by
L.
Native to
Ontario, Massachusetts, New Hampshire +42
Wild records
146 in range · 113 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; 22 records within 1 km of a botanic garden, herbarium or zoo left out (17 at a botanic garden or arboretum, 1 at a herbarium, 4 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 24.50_-102.500, lapse-corrected -32 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 294 datasets via GBIF.org; each carries its own licence.

Cultifolio

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