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Weed Identification

redroot amaranth

Family

Amaranthaceae

Scientific Name

Amaranthus retroflexus

Other Common Names:

careless weed
redroot pigweed
rough pigweed

Habit

This erect summer annual can be found flowering from July through October.

Leaves

The alternate leaves are ovate with wavy margins. The leaves are hairy on the lower surface, along the prominent veins. The stout, hairy stem can grow up to 6 1/2 feet in height.

Identifying Characteristics

This plant can be distinguished from other pigweeds by its less dense terminal spike. The first true leaves of this plant are alternate, unlike any of the other pigweeds.

Flower Seed Head

The small greenish flowers occur in terminal spikes. Smaller spikes of flowers may be found at the leaf axils.

Seed Fruit

The glossy black seeds each form inside a 2 mm long utricle that splits open at maturity.

Where Found

This plant can be found in pastures, along roadsides, and other disturbed soils.

Growth Habit

upright and nonwoody

Thorns or Spines

not present

Approximate Flower Diameter

pencil

Dominant Flower Color

green

Leaf Hairs

Varies: 
no hairs
has hairs

Leaf Shape

spatulate

Leaf Arrangement

alternate

Leaf Margin

wavy

Leaf Structure

simple

Leaf Stalk

longer than leaf

Stem Hairs

has hairs

Stem Cross Section

round or oval

Milky Sap

not present

Root Structure

Varies: 
fibrous
taproot

Life Cycle

summer annual

Ochrea

not present

Plant Type

Herb