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Amaranthus retroflexus - redroot amaranth

Scientific Family
Amaranthaceae
Other common names
careless weed
pigweed
red-root amaranth
redroot pigweed
rough pigweed
Plant type
Forbs and Subshrubs
Origin
Native
Lifecycle
Annual
Similar species
Amaranthus powellii
Height
To 6 feet
Riparian
Yes
Erect, branching, leafy annual with dense, stiff terminal clusters of inconspicuous green flowers and spine-like scales. The plant is named for its pinkish to red taproot.
Plants densely to moderately pubescent, branched moderately large and usually green inflorescences, sometimes with reddish tint and both male and female flowers on the same plant distinguish that from other Amaranthus sp. .

Habitat

Banks of rivers, lakes, and streams, disturbed habitats, agricultural fields, railroads, roadsides, waste areas.
Plant Community
Riparian
Disturbed Areas
Low elevation
0
High elevation
8200

Flower Characteristics

Small, green inconspicuous flowers and spine-like scales are tightly arranged to form dense, stiff, terminal clusters with smaller clusters between the main stem and leaf stalks.
Flower color
Green
Flower shape
Inconspicuous
Tubular
No
First bloom month
June
Last bloom month
November
Flower clusters
Elongated

Leaf and Stem Characteristics

Stems are coarse with the lower part red or red-striped. Leaves are up to 7 inches long and their stalks are up to 3 inches long. Leaves are broad and lance-shaped with prominent veins and wavy margins.
Leaf type
Simple
Leaf color
Green
Leaf shape
Round or oval
Leaf margin
Other
Leaf attachment
Alternate
Leaves clasp
No
Leaf hairs
Leaves & stems
Spines
No

Fruit and Seed Characteristics

Tiny capsules are less than 1/17 inch long. The capsules split open in the middle to release one seed.
Fruit type
Capsule
The dark brown to black seeds are round, glossy, and roughly 1/25 of an inch in diameter.