Palmer Amaranth (Amaranthus palmeri)
(restricted seed), found in isolated areas of Montana
Quick ID
- Smooth, hairless stems
- Petiole (leaf stalk) often longer than leaf blade
- Dioecious, individual plants are either male or female
- Seed heads on female plants are prickly and on both sexes are terminal and can be up to 3’ long, but can be shorter too
- Leaves are diamond or oval-shaped
Palmer Amaranth Plant
Video Information
Weed Images
Weed Specifications
| Type | Information |
|---|---|
| Toxicity | Non-toxic |
| Best Management Practices |
Prevention and early detection and rapid response, awareness, field scouting, equipment sanitation, communication, trusted seed source. |
| Habitat | Same as all pigweeds, mainly cropland and field edges, such as roadsides, fence lines, ditches, and other disturbed areas. |
| Stem | Reddish colored, smooth and hairless, and up to 8’ tall; other pigweeds in Montana, most predominantly redroot pigweed, have short, dense hairs and rarely exceed 3’ tall. |
| Leaves | Alternate, egg to diamond-shaped, the same length or shorter than the petiole, sometimes have a tiny hairlike tip. |
| Lifespan | Warm season annual, emerges throughout the growing season, not at specific times. |
| Similar Looking Plants | Redroot pigweed and other pigweeds, waterhemp. |
| Important Information | Produce hundreds of thousands of seeds per plant, plants can grow 2-3” per day and up to 8’ tall, can dramatically cut crop yields, resistant to multiple herbicide Modes of Action; spreads by seed, feed, mobile farm equipment, etc.; on Montana’s eastern border, it is found only two counties away; very hard to identify and expert assistance is necessary for confirmation, including being sent to a lab for genotyping. |
