The six weedy Amaranthus species at the weed garden have grown quite a bit, but I'm not sure how much easier it is to differentiate a few of the species. The six pigweeds are Palmer, Powell's and spiny amaranth, waterhemp, and redroot and tumble pigweed (not in that order!!). The purpose of this exercise is to demonstrate how easy it would be to overlook Palmer amaranth in fields if time isn't taken to make sure exactly what Amaranthus you're dealing with. Scroll to the bottom to find the answers.
Answer key:
#1 - Spiny Amaranth
#2 - Palmar Amaranth
#3 - Powell’s Amaranth
#4 - Redroot Pigweed
#5 - Tumble Pigweed
#6 - Waterhemp
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- Retired Weed Scientist and Professor of Agronomy