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Amaranthus retroflexus

Amaranthus retroflexus L.

Amaranthus retroflexus L. var. salicifolius I.M. Johnst.

Pigweed

KingdomPlantaePlants, but not fungi, lichens, or algae
SubkingdomTracheobiontaVascular plants—plants with a “circulatory system” for delivering water and nutrients
DivisionMagnoliophytaFlowering plants, also known as angiosperms
ClassMagnoliopsidaDicotyledons—plants with two initial seed leaves
SubclassCaryophyllidaeCacti, many other succulents, carnivorous plants, and leadworts
OrderCaryophyllalesIncludes cacti, carnations, amaranths, ice plants, and many carnivorous plants
FamilyAmaranthaceaeAmaranth family
GenusAmaranthusContraction of Greek ἀμάραντος (amarantos), “unfading,” with ἄνθος (anthos), “flower”
Speciesretroflexus

About plant names...

Although other members of the Amaranthus genus are popular as food sources or landscaping plants, pigweed doesn’t get much respect. It is a common, gangly, rather unappealing weed. It is native to the tropical regions of the Americas, but has become more widespread.

Identification: Pigweed can reach 9' (2.7 m), but I usually see much smaller plants. Stems are often reddish near the base. Leaves are between 3-7" (7.6-17 cm) long. The flowers are green, about ¾" (1.9 cm) wide and 2-8" (5-20 cm) long.

Amaranthus retroflexus (Pigweed)

From Thomé, Prof. Dr. Otto Wilhelm, Flora von Deutschland Österreich und der Schweiz., 1885

Edibility: This is edible, and is eaten in some regions, but it may be high in oxalic acid or nitrates, so it should be boiled and the water discarded. Many other species of Amaranthus, such as pendent amaranth, serve as significant food sources.

Online References:

Amaranthus retroflexus on the Virginia Tech Weed Identification Guide

Amaranthus retroflexus on the USDA Forest Service's Fire Effects Information Database

Amaranthus retroflexus at the Lady Bird Johnson Wildflower Center

Amaranthus retroflexus on Invasive.org, Center for Invasive Species and Ecosystem Health

Amaranthus retroflexus on Ontario Wildflowers

Amaranthus retroflexus on CalPhotos

Amaranthus retroflexus on Plants for a Future, a resource and information centre for edible and otherwise useful plants

Amaranthus retroflexus on the Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries

Amaranthus retroflexus at the University of Wisconsin's Robert W. Freckmann Herbarium

Amaranthus retroflexus on eFloras

Amaranthus retroflexus description by Thomas H. Kent, last updated 20 May 2018.

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Amaranthus retroflexus (Pigweed)

6/1/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 12 × 17" (29 × 44 cm)

Amaranthus retroflexus (Pigweed)

6/1/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 12 × 17" (29 × 44 cm)

Range:

About this map...