The weedy pigweeds are considered to be the worst weed(s) interfering with US
agriculture. They are well adapted to survive, thrive and interfer in agroecosystems. One
of the reasons they are so successful is their diversity.
There are 9 different pigweeds that we will study in this section. Each of these pigweed species overlap in characteristics, one of the important reasons they are often hard to indentify.
Follow the material presented below. This section is divided into several sections, each one will help you differentiate the pigweeds in a different way.
A species differences table of key features used to separate these 9 species is provided below for overview purposes. In 3 of the sections below, parts of that table are reproduced to aid in ID of that section (e.g. seedhead types are in a table frame with the Flower & Seedhead pictures).
redroot pigweed (Amaranthus retroflexus) summer annual
smooth pigweed (Amaranthus hybridus) summer annual
Powell amaranth (Amaranthus powellii) summer annual
spiny pigweed (Amaranthus spinosus) summer annual
tumble pigweed (Amaranthus albus) summer annual
prostrate pigweed (Amaranthus blitoides) summer annual
common waterhemp (Amaranthus rudis) summer annual
tall waterhemp (Amaranthus tuberculatus) summer annual
Palmer amaranth (Amaranthus palmeri) summer annual