Palmer Amaranth

Other names: Carelessweed, pigweed, Palmer pigweed

Scientific name: Amaranthus palmeri S. Watson

Family: Amaranthaceae

Description: A problematic warm-season annual common in row-crop fields across Texas.  If uncontrolled, female plants can produce vast quantities of seed. Glyphosate (Roundup) resistant populations exist across the Texas Coastal Bend.

Stems: Without hairs, may be red or green in color (and all shades between).

Leaves: Simple, alternate, ovate to lanceolate, and without hairs.  Margins entire.  Leaf petioles are often shorter than leaf blade.  Occasionally, leaves exhibit a white chevron-shaped watermark.

Inflorescence: A dioecious species (separate male and female plants).  Inflorescence a spike-like structure than can reach 1 to 2 feet long.  Female flowers with bracts subtending calxy.  These bracts become spine-like and prickly to touch as flowers mature. Petals absent.  Male flowers similar to female flowers in appearance, however will shed pollen and are typically soft to touch.

Seed: Glossy, dark brown to black, 1 mm in diameter.

Photos

Seedling

Seedling

Mature plants

Mature plants

Seed

Seed

 

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