Amaranthus palmeriS.Watson

carelessweed

WFO wfo-0000530390 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Amaranthus palmeri, photographed by 胡正恆(Jackson Hu)
fig. a 胡正恆(Jackson Hu), CC BY 4.0 / 2022-06-10 / obs. 205397334

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

Native range 10 botanical countries

Regions where Amaranthus palmeri is native: Arizona, California, Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southwest, Nevada, New Mexico, Texas ArizonaCaliforniaMexico CentralMexico GulfMexico NortheastMexico NorthwestMexico SouthwestNevadaNew MexicoTexas
Native distribution of Amaranthus palmeri, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows.
RegionTDWG codeContinent
Arizona ARI NORTHERN AMERICA
California CAL
Mexico Central MXC
Mexico Gulf MXG
Mexico Northeast MXE
Mexico Northwest MXN
Mexico Southwest MXS
Nevada NEV
New Mexico NWM
Texas TEX

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Flowering 61 in flower of 95 examined

Proportion of examined Amaranthus palmeri in flower, by month
Month In flower Examined Share 95% interval
Jan 1 3 too few examined
Feb 1 1 too few examined
Mar 1 2 too few examined
Apr 5 5 100% 57% to 100%
May 4 6 67% 30% to 90%
Jun 4 7 57% 25% to 84%
Jul 6 10 60% 31% to 83%
Aug 18 24 75% 55% to 88%
Sep 13 16 81% 57% to 93%
Oct 4 8 50% 22% to 78%
Nov 3 8 38% 14% to 69%
Dec 1 5 20% 4% to 62%

Peak flowering in Apr. Each bar is the share of Amaranthus palmeri observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 61 of 95 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 3 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Where it actually grows measured, from 1,870 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -3.6 °C 4.7 °C 15.3 °C
Warmest month, mean daily high 29.8 °C 34.7 °C 41.0 °C
Annual rainfall 216 mm 617 mm 1,112 mm
Rainfall in the driest quarter 6 mm 37 mm 191 mm

It is found where winters bring light frost. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,870 research-grade observations of Amaranthus palmeri that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

Also published as 1 synonym

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Amaranthus palmeri var. glomeratus Uline & W.L.Bray

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
  4. Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.