Palmer Amaranth

Amaranthus palmeri

Leaves: Diamond-shaped and sometimes exhibiting a white or purple, V-shaped watermark (chevron) on them. Leaf petioles (especially older leaves) are as long/longer than the leaf blades.

Stems: Smooth (not hairy) and green, red, or green-red striped.

Height: Can grow very tall, up to 10 feet, especially in competition with corn.

Flowers: Produces male and female flowers on separate plants. Flowers are primarily produced on long (up to 2-3 feet, or more, in length) terminal flower heads or spikes. Male flowers will have yellow anthers with pollen. Female flowers will have sharp bracts associated with them.

Herbicide resistances in US: WSSA Groups 2, 3, 4, 5, 9, 10, 14, 15, 27.

palmer amaranth leaf with long petiole — Palmer amaranth has diamond shaped leaves with petioles longer than the blades

Images above: Palmer amaranth has diamond shaped leaves with petioles longer than the blades

palmer amaranth in pot with long petrioles — Palmter amaranth has long petioles.

chevrons on palmer amaranth leaves. — Palmer amaranth plants typically have chevrons (V-shaped markings) on their leaves.

Images above: Palmer amaranth plants typically have long petioles (left) and chevrons (V-shaped markings) on their leaves.

V-shaped marks on palmer amaranth leaves — V-shaped marks on leaves

Images above: Palmer amaranth petioles are longer than leaf blade (left). V-shaped marks on leaves (right).

mature Palmer amaranth in corn field — Palmer amaranth in corn field

Images above: Palmer amaranth in corn field initiating flowering (left). Female flowers with bracts (right).

female palmer bracts — Palmer amaranth female flowers with bracts (left) and stigma in female flowers (right).

palmer amaranth in greenhouse — A large female Palmer amaranth plant in a Cornell Greenhouse exhibiting multiple flower heads that are many branched.

Images above: Left to right, female Palmer amaranth flowers with bracts, stigma in female flowers and a large female Palmer amaranth plant in a Cornell Greenhouse exhibiting multiple, many-branched flower heads.

palmer amaranth male flowers with anthers full of pollen — Male palmer amaranth flower head (left) with anthers full of pollen (right).

Images above: Left to right, Palmer amaranth male flower head, anthers of male flowers full of pollen, and male Palmer amaranth in corn field.

Image above: Female Palmer amaranth flowers in the field.

Images above: Female Palmer amaranth flowers up close.

male palmer amaranth flowers in the field at harvest time

Image above: Male Palmer amaranth flowers in the field.

Image above: Male Palmer amaranth flowers up close.

palmer amaranth seedling — Palmer amaranth seedling

Image above: Palmer amaranth cotyledons (left) and seedling (right).

Palmer amaranth vs. waterhemp flowers

Female flowers of Palmer amaranth (left) vs. waterhemp (right).

Above image: Waterhemp female flowers (left) and Palmer amaranth female flowers (right).

Palmer amaranth female flowers will have sharp, stiff bracts, whereas waterhemp will not. Waterhemp flowers are less tightly clustered on the stem compared to Palmer amaranth.

Palmer amaranth vs. waterhemp leaves

Waterhemp (lower left) vs. Palmer (upper right) leaves

Left image above: Waterhemp (lower left) vs. Palmer amaranth (upper right) leaves. Right image above: Waterhemp (left) vs Palmer amaranth (right) leaves

Leaves of Palmer amaranth are more distinctly, diamond-shaped as compared to waterhemp, which has long and linear leaves which can sometimes approach oval-shaped.