Seed leaves are long and narrow. First true leaves are strongly egg-shaped with a deep notch at the tip.
Seedlings become hairy as they mature.
Smooth pigweeds are tall plants with few branches. Stems and leaves tend to be red or green. Leaves are egg-shaped. Stem and leaves tend to be slightly hairy, but not roughly hairy like redroot pigweed. Seedhead branches are numerous, long, thick, and slightly prickly.