Prostrate Pigweed

Amaranthus blitoides

Alternate names
Prostrate Amaranth

Weed Description
A prostrate summer annual that desires dry open fields, pasturesn and roadsides. Prostrate pigweed is native to North America and is found across the entire United States.

Seedlings
Cotyledons are lanceolate to linear. The lower surface and stem is deep red while the upper surface is shiny. Leaves are indented or notched at the tip.

Leaves
Leaves are alternate, simple, shiny, and broadest at the tips.

Stems
Prostrate with the tips curving upward, hairs are present, and stems are red in color.

Flowers
Are produced from June through August and are formed in small clusters only in the axils of the leaves and not on terminal spikes.

Roots
Fibrous root system from a taproot.

Seeds
Glossy, black, circular seeds that measure 1.5mm in diameter, and are convex on both sides.

Identifying Characteristics
Prostrate pigweed differes form other amaranthus species due to seedheads that are produced in the axils of the leaves and not in terminal spikes. Seedlings have an indention at the tip which is a common characteristic of pigweed species. Prostrate spurge is also commonly confused with prostrate pigweed, but spurge exudes a white milky sap when cut and leaves are slightly smaller.

Office of Programs

University of Missouri

Prostrate Pigweed

Amaranthus blitoides