Scientific Name: Amaranthus spinosus

Common Name: spiny amaranth

Other Common Names: prickly amaranth, thorny amaranth

Habit: This summer annual can be found flowering from May through October.

Leaves: The alternately arranged leaves occur on long petioles and are ovate in shape. The leaves grow from 1 1/4 to 2 1/2 inches in length. The erect branching stems can exceed 5 feet in height.

Identifying Characteristics: At the base of each leaf petiole are two 5 to 10 mm long spines, giving the Spiny Pigweed its name.

Flower Seed Head: The seedheads occur in clusters at the ends of stems arising from the leaf axils.

Seed Fruit: The seeds develop in a utricle 1 1/2 to 2 mm in length.

Where Found: This plant prefers disturbed sandy loam soils, but can grow in a variety of conditions.

  • Life cycle: summer annual

  • Milky sap: Not Present

  • Plant type: Herb

  • Thorns: Present

  • Plant family: Amaranthaceae

  • Leaf arrangement: alternate

  • Leaf shape: oval

  • Ochrea: Not Present

  • Leaf margin: entire

  • Stem hairs: no hairs

  • Flower color: green

  • Growth habit: upright and nonwoody

  • Stem: round or oval

  • Leaf structure: simple

  • Leaf hairs: no hairs

  • Flower diameter: pencil

  • Flower symmetry: radial symetery; bilateral symetry

  • Root structure: taproot

  • Leaf stalk: shorter than leaf