Amaranthus blitoides

Scientific Name Amaranthus blitoides S. Watson
Common Names English: Prostrate pigweed, prostrate amaranth; French: Amarante fausse blite; German: Niederliegender Amarant; Spanish: Amaranto
Description Summer annual with branched stems, 15 to 60 cm (5.90 - 23.62 inch) wide, more or less prostrate and mat-forming. A. blitoides produces a taproot with a secondary fibrous root system.

Descriptions

Characteristic Features

Dry persistent calyx and bracts.

Young Plant

Cotyledons are linear or lancelote, first leaves are widest at the apex with magenta coloring on the underside, apex is slightly notched.

Cotyledons

Linear or lancelote.

Stems

Prostrate or ascending (very rarely suberect), much-branched (usually from base), 0.1-1 m (3.93 - 39.37 inch).

Leaves

Alternate leaves are up to 5 cm (1.97 inch) long and half as much across. They are dark green, glabrous, obovate (spoon-shaped), and smooth along the margins. Each leaf tapers gradually to a slender petiole.

Propagatio Organs

Flowers

Short clusters of light green flowers develop from the axils of the leaves. Each plant is monoecious and produces separate male (staminate) and female flowers (pistillate). The male flowers have 4-5 sepals, 3 stamens, and no petals, while the female flowers have 4-5 sepals, an ovary with 3 styles, and no petals. The sepals of both kinds of flowers are about 1/8 in length or a little longer and oblong-lanceolate in shape. Underneath the flowers, are several bracts that are the same length or a little larger than the sepals. Like the sepals, the bracts are light green and oblong-lanceolate; their tips are pointed, but not spiny.

Flowering Period

Summer-fall.

Fruit

Bladder-like capsule (or utricle) containing a single seed. This capsule is globoid and smooth while young. Later, it splits open around the middle to release the seed.

Seeds

Black, lenticular to broadly plumply lenticular, 1.3 to 1.6 mm(0.05 - 0.06 inch) diam., rather dull.
Main germination period is from September-October.

Viability Of Seeds

More than 20 years.

Propagation

Plants pollinated by wind.

Occurrence

Habitat

Roadsides, riverbanks, railroads, fields, waste places, sandy flats; widely and successfully naturalized almost everywhere in temperate North America and in many subtropical to warm-temperate regions.

Soil

Coarse sandy soils.

Additional Crop Information

Sugarbeet, soybean, turf grass, vegetables.

Agricultural Importance

A. blitoidus is very competitive for water and nutrients, produces a persistent seed bank in the soil and is invasive in warm climates. Multiple resistances have evolved to herbicides. Particular biotypes are known to have resistance to triazines and sulfonylureas and they may be cross-resistant to further herbicides.

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