An official website of the United States government.

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

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
Image use policy

Palmer amaranth in field

Credit

Howard F. Schwartz, Colorado State University

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.

Distribution / Maps / Survey Status

Videos

Selected Resources

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

Partnership
Federal Government
State and Local Government
Academic
Citations