Common: Careless Weed, Dioecious Amaranth, Palmer Amaranth, Palmer’s Pigweed
Native to every US state except Alaska, Hawaii, Washington, Idaho, Oregon, Montana, Wyoming, North and South Dakota, Minnesota, Iowa, Michigan, Indiana, Alabama, Delaware, Connecticut, Rhode Island, Vermont, New Hampshire, and Maine
Palmer’s Amaranth is the most aggressive pigweed species with respect to growth rate and competitive ability. It is a threat to several farm crops, specifically cotton and soybeans, and it is highly resistant to common herbicides. It can grow from 2 to 5 inches in three days. This considerably outpaces the farm crop growth.The male plant produces pollen and the female plat produces seed. The pollen is carried by wind to the female plant. The female plants reach around 10 feet tall with 5-6-inch stems and seed heads more than 1 foot long. Male plants are smaller and noncompetitive. The flower clusters are rounded at the tip and vary in size. The leaves are ovate to round with long petioles with spikes at the tip. Palmer’s Amaranth is highly cross-reactive with rough pigweed, waterhemp, and Lamb’s quarters.