Other names: Carelessweed, pigweed, Palmer pigweed
Scientific name: Amaranthus palmeri S. Watson
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.