American Redroot Pigweed Gardens for People Not Parasites, Pests, Pigs

Summary: American redroot pigweed gardens work away from pigs, outside Manitoba and Quebec, Canada, and with parasite, pest and seed controls in effect.

terminal floral spike of redroot pigweed (Amaranthus retroflexus); Bozeman, Gallatin County, southwestern Montana; Sept. 28, 2008: Matt Lavin, CC BY SA 2.0, via Flickr

American redroot pigweed gardens are likely to appear beyond their native ranges, from northern Mexico to the southern United States, because of the annual's assiduous expansion northward toward, and westward through, Canada.

Outdoor presences bring possible weed designations, in effect in the Canadian provinces of Manitoba and Quebec, upon the nitrate-accumulating, pest-hosting annual for seed production and viability. Frost sensitivity challenges introduced and naturalized life cycles of the Amaranthaceae family member of herbs and shrubs less in the twenty-first century's globally warmed climate changes. The fast-growing amaranth herb dominates frost-free months by drawing European corn borers, green peach aphids, livestock-poisoning nitrates from soil, tarnished plant bugs and vegetable viral diseases.

The common names Chinaman's greens, green amaranth, redroot and redroot amaranth epitomize redroot pigweed's outdoor good and careless weed and rough pigweed redroot pigweed's outdoor bad.

Seedlings furnish dark red stems for lance-shaped, red-purple-bottomed, 0.14- to 0.39-inch- (3.5- to 10-millimeter-) long, 0.04- to 0.08-inch- (1- to 2-millimeter-) wide embryonic leaves called cotyledons. They quickly grow into bristly, 3.28-foot- (1-meter-) tall plants with branched, pale or reddening green, rough-textured stems, with fleshy, pink-red, short taproots and with indeterminate habits.

The scientific name Amaranthus retroflexus hints at the backward-bending, drooping retroflex impacts that hairy, long stalks have upon alternate-positioned, diamond- to oval-shaped, smooth- or wavy-margined leaves. Green, maturing leaves increase to 1.57- to 5.91-inch- (4- to 15-centimeter-) long, 0.39- to 2.76-inch- (1- to 7-centimeter-) wide sizes, with hairy margins and white-veined undersides.

Bristly, modified leaves called bracts juggle flower- and foliage-like looks around dense, irregular, terminal flower-clustered inflorescences called panicles in June- to November-blooming American redroot pigweed gardens.

A maximum of three papery, spine-tipped bracts, each 0.09 to 0.32 inches (2.5 to 8 millimeters) long, keeps guard duty around every panicle of green flowers. The 0.08- to 0.16-inch- (2- to 4-millimeter-) wide flower looks bristly because of the surrounding bracts and, if female, green with one pistil and five stamens. A maximum of five spine-tipped sepals, each 0.16 to 0.32 inches (4 to 8 millimeters) long, opposite five stamens, manages bristly, green-purple looks for male flowers.

Redroot pigweed needs eight weeks to navigate life cycles from germinating and leafing to flowering and fruiting and thereby nurtures two generations in one growing season. At maximum habit and height, it offers American redroot pigweed gardens 150,000 disc-shaped, shiny seeds from 0.06- to 0.08-inch- (1.5- to 2-millimeter-) long, single-seeded fruit capsules.

The dark red-brown to black, 0.04- to 0.05-inch- (1- to 1.3-millimeter-) wide seeds promise 40-year viability if positioned in the soil's top 0.98 inches (2.5 centimeters).

Cultivators of such nightshade family members as eggplants, potatoes, tobacco and tomatoes quake at the sight of redroot pigweed, host to the parasitic plant hemp broomrape. They likewise resist the presence of such similarly crop-threatening, diversity-compromising, herbicide-tolerant redroot pigweed relatives as devil's horsewhip, Palmer's rough-fruit, slender and spiny amaranths, and prostrate pigweed. Alabama, Arkansas, California, Florida and South Carolina share Arizona and Texas weed-slamming alligator weed and Massachusetts, Minnesota, North Carolina, Oregon and Vermont weed-slamming sessile joyweed.

American redroot pigweed gardens treat gardeners and naturalists to green, green-purple, pink-red, red, red-brown, red-green, red-purple and white palettes whose eco-friendliness turns around taming truculent seeds.

redroot pigweed (Amaranthus retroflexus); southeastern Michigan; Aug. 27, 2016: F.D. Richards, CC BY SA 2.0, via Flickr

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

terminal floral spike of redroot pigweed (Amaranthus retroflexus); Bozeman, Gallatin County, southwestern Montana; Sept. 28, 2008: Matt Lavin, CC BY SA 2.0, via Flickr @ https://www.flickr.com/photos/plant_diversity/3704266070/

redroot pigweed (Amaranthus retroflexus); southeastern Michigan; Aug. 27, 2016: F.D. Richards, CC BY SA 2.0, via Flickr @ https://www.flickr.com/photos/50697352@N00/29189207391/

For further information:

"Amaranthus retroflexus L." Tropicos® > Name Search.
Available @ http://www.tropicos.org/Name/1100012

Dickinson, Richard; and Royer, France. 2014. Weeds of North America. Chicago IL; London, England: The University of Chicago Press.

Linnaeus, Carl. 1753. "10. Amaranthus retroflexus." Species Plantarum, vol. II: 991. Holmiae [Stockholm, Sweden]: Laurentii Salvii [Laurentius Salvius].
Available via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/359012

Weakley, Alan S.; Ludwig, J. Christopher; and Townsend, John F. 2012. Flora of Virginia. Edited by Bland Crowder. Fort Worth TX: BRIT Press, Botanical Research Institute of Texas.