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.

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

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

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

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

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.

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.

Image above: Male Palmer amaranth flowers in the field.

Image above: Male Palmer amaranth flowers up close.

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

Palmer amaranth vs. waterhemp flowers

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

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.