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National Invasive Species Information Center
U.S. Department of Agriculture
  1. Home
  2. Terrestrial Invasives
  3. Terrestrial Plants
  4. Palmer Amaranth

Palmer Amaranth

Scientific Name

Amaranthus palmeri S.Watson  (ITIS)

Common Name

Palmer amaranth, palmer pigweed, carelessweed

Native To

Southwestern U.S. (Ward et al. 2013)

Date of U.S. Introduction

First reported outside of its native range in Virginia in 1915, but was not a significant weed in the Southeast until the 1990s (Ward et al. 2013); glyphosate-resistant varieties first appeared in 2004 (Culpepper et al. 2006)

Means of Introduction

Most likely through the transport of contaminated seed; some recent infestations in the Midwest were caused by contaminated Conservation Reserve Program seeding mixes (Ward et al. 2013; Murphy et al. 2017)

Impact

One of the most economically important weeds of corn, cotton, and soybean; some populations are resistant to glyphosate and other herbicides (Ward et al. 2013)

Palmer amaranth

Palmer amaranth in field

Credit

Howard F. Schwartz, Colorado State University

Source
Invasive.org

Find more images

Spotlights

  • Understanding the Science Behind Pigweed’s Amazing Adaptation

    • Dec 20, 2021

    • USDA. ARS. Tellus.

    • Pigweed is a major challenge to our farmers and growers. It is extremely resilient and resistant to many herbicides, posing a significant threat to the agriculture industry. ARS scientists in Stoneville MS, along with collaborators from Clemson University, are researching the pigweed itself to find ways to mitigate this highly adaptable weed.

  • Climate Change Impacts on Palmer Amaranth

    • United States Department of Agriculture. USDA Climate Hubs.

    • Palmer amaranth (Amaranthus palmeri S. Watson) is an annual plant in the pigweed family (Amaranthaceae). It is native to the southwest United States/northern Mexico deserts and is currently increasing its range across the country. USDA NRCS, their partners, as well as farmers and landowners are working to eradicate these infestations before they spread to new areas. Midwest Climate Hub fellow, Dr. Erica Kistner-Thomas is getting a jump on how the distribution of Palmer amaranth will change from current to future climate conditions. Climate change is going to benefit this heat-tolerant weed by lengthening its growing season, boosting seed production and expanding its potential U.S. geographic range.

Distribution / Maps / Survey Status

Videos

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Selected Resources

The section below contains highly relevant resources for this species, organized by source.

Partnership
Federal Government
State and Local Government
Academic
Citations