Scientific Family
Amaranthaceae
Other common names
Palmer's amaranth
pigweed
Plant type
Forbs and Subshrubs
Origin
Native
Lifecycle
Annual
Similar species
Amaranthus retroflexus, Amaranthus hybridus, Amaranthus rudis
Height
To 6 feet
Riparian
Yes
An erect, tall, summer annual with long panicles of small, green, inconspicuous flowers. It is an aggressive, invasive weed native to the desert regions of the southwest.
Male and female flowers on different plants; sepals of female flowers broadened upward, blade noticeably wider than the base and not fringed with hairs. A long leaf stem distinguishes Amaranthus palmeri from other species.
Habitat
Can occur in non-wetlands and wetlands; roadsides, ditches, fields, arroyos.
Plant Community
Riparian
Disturbed Areas
Desert Scrub
Low elevation
325
High elevation
3800
Flower Characteristics
Female plants have a long main terminal flower head, 1-1/2 feet (or more). The inconspicuous flowers have stiff, sharp bracts that give the panicle a prickly feeling when touched.
Flower color
Green
Flower shape
Inconspicuous
Tubular
No
First bloom month
August
Last bloom month
November
Flower clusters
Elongated
Leaf and Stem Characteristics
2 to 8 inches long. The petioles will be as long (or longer) than the leaf blade; leaves are arranged symmetrically around the stem. Stems are erect, branched, and usually reddish. Roots are mostly taproot and reddish in color.
Leaf type
Simple
Leaf color
Green
Leaf shape
Triangular
Leaf margin
Smooth
Leaves clasp
No
Leaf hairs
None
Spines
No
Fruit and Seed Characteristics
Fruit type
Achene
Fruit color
Reddish-brown
Shiny, reddish-brown in color; tiny, less than 1/16 inch.