Amaranthus retroflexus L.

First published in Sp. Pl.: 991 (1753)
This species is accepted
The native range of this species is Mexico. It is an annual and grows primarily in the temperate biome.


Amaranthaceae, C. C. Townsend. Flora Zambesiaca 9:1. 1988

Morphology General Habit
Annual herb, erect or with ascending branches, (6) 15–80 (100)cm., simple or branched (especially from the base to about the middle of the stem).
Morphology Stem
Stem stout, subterete to angled, densely furnished with multicellular hairs.
Morphology Leaves
Leaves furnished with multicellular hairs along the lower surface of the primary venation and often the lower margins, long-petiolate (petioles up to c. 6 cm., in robust plants not rarely equalling the lamina), lamina ovate to rhomboid -or oblong-ovate, (1) 5–11 × (0.6) 3–6 cm., obtuse to subacute at the mucronulate apex, shortly cuneate to attenuate into the petiole.
Morphology Reproductive morphology Flowers
Flowers in greenish or rarely somewhat pink-suffused, stout, axillary and terminal spikes, which are usually shortly branched to give a lobed appearance, more rarely with longer branches, the terminal inflorescence more or less paniculate, very variable in size, male and female flowers intermixed, the latter generally much more plentiful except sometimes at the apex of the spikes.
Morphology Reproductive morphology Inflorescences Bracts
Bracts and bracteoles lanceolate-subulate, pale-membranous with a prominent green midrib excurrent into a stiff, colourless arista, longer bracteoles subequalling to twice as long as the perianth.
Morphology Reproductive morphology Flowers Perianth
Perianth segments 5, those of the male flowers 1.75–2.25 mm., lanceolate-oblong, blunt to subacute, those of the female flowers 2–3 mm., narrowly oblong-spathulate to spathulate, obtuse or emarginate, more or less green-vittate along the midrib, which ceases below the apex or is excurrent in a short mucro.
Morphology Reproductive morphology Flowers Gynoecium Stigma
Stigmas 2–3, patent-flexuose or erect, c. 1 mm.
Morphology Reproductive morphology Fruits
Capsule subglobose, c. 2 mm., usually shorter than the perianth, circumcissile, with an indistinct neck, rugose below the lid.
Morphology Reproductive morphology Seeds
Seed black and shining, compressed, c. 1 mm., almost smooth centrally, faintly reticulate around the margins.

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E.

Predicted extinction risk: not threatened. Confidence: confident


  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
  • Flora Zambesiaca

    • Flora Zambesiaca
  • Herbarium Catalogue Specimens

    • Digital Image © Board of Trustees, RBG Kew
  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at and
    • © Copyright 2023 World Checklist of Vascular Plants.
  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at and
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants.
  • Kew Science Photographs

    • Copyright applied to individual images