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A Forager’s Year

No. 129

Redroot pigweed

Amaranthus retroflexus (also A. hybridus)

redroot amaranth, rough pigweed; also smooth pigweed

Nut & seed ripe seeds (tiny and shiny black; whole, popped or ground)

Drawing: Britton & Brown, Illustrated Flora (1913)

Find
Patchy
Effort
Real work
ID risk
Beginner
Origin
native
Safety marks
  • Toxic parts
Uses
  • Eat raw / salad
  • Baking & desserts
  • Flour
  • Roasted nuts

Season

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

in season peak

Picking: The rules are unclear. Ask the park. See Where you may pick.

What these mean

Find

1 Everywhere · 2 Common in the right habitat · 3 Patchy · 4 Elusive. This is about how much there is, not whether you may pick it. It is based on iNaturalist sightings within 25 km (about 15 miles) of downtown DC, counted on October 3, 2026. The four rules that each plant’s “Find” reason refers to: (A) the estimate is the confirmed sightings, plus the unconfirmed ones (scaled down where the plant has lookalikes in its genus), plus the sightings marked as planted; (B) the tier by estimate: 1,500 or more is tier 1, 250–1,499 tier 2, 50–249 tier 3, under 50 tier 4; (C) tier 1, Everywhere, also needs a source saying the plant is common in lawns, sidewalks, yards or gardens, vacant lots or towns, or at least one DC street tree of it per km of sidewalk, otherwise it is tier 2; (D) if a reliable source says the plant is rare in this region, or that wild plants rarely bear the harvest, only planted sightings count. iNaturalist is a website and phone app where people post photos of the plants and animals they see. A sighting is “research grade” when other users have confirmed what it is; “needs ID” sightings are not confirmed yet, and “cultivated” ones are marked as planted.

Effort

1 Grab & eat · 2 Quick kitchen prep (under about 30 minutes) · 3 Real work (hours, or cooking needed for safety) · 4 Project (days or equipment). Scored on the simplest worthwhile use; each plant’s page says why.

ID risk

How hard it is to harvest safely. Beginner: no dangerous lookalike, and the edible part is not easily confused with a toxic part. Careful: a toxic lookalike, or toxic parts that end up in the harvest unless removed (for example elderberry stems, unripe ground cherries), or other parts of the plant rated medium-or-higher toxicity, with reliable features to separate them. Expert only: a potentially deadly lookalike that is hard to separate, or (for not-recommended harvests like pokeweed) a plant whose safe preparation can’t be guaranteed. Toxic parts that are obviously separate and thrown away anyway (pits, seeds, skins) don’t raise it; the Toxic parts mark carries that warning.

Native or not, and the invader stars

Origin is where the plant comes from: native, non-native, or mixed (the harvest covers both). The stars rate plants on invasive plant lists: ★★★ Virginia DCR “High” or Maryland prohibited invasive · ★★ Virginia “Medium” · ★ Virginia “Low” · ☆ listed only by the Maryland Invasive Species Council or the Mid-Atlantic Plant Invaders guide (advisory) · no stars: native or not listed.

Safety marks and flags

Deadly lookalike / Toxic lookalike: a cited source names a lookalike of that danger, recorded near DC (an iNaturalist sighting within 25 km, a DC street tree, or a Smithsonian listing for DC) and looking like the part you eat. Other lookalikes are still listed, marked “not recorded near DC” or as not looking like the part you eat. Deadly means a source says eating it may be fatal or calls it deadly, or NC State rates it high severity with life-threatening symptoms (sources sometimes disagree; for example Virginia creeper). Each plant’s Lookalikes list says how to tell them apart; “harmless (may be edible)” lookalikes are listed so you know a mix-up isn’t dangerous. Cook first: cooking is needed for safety (for daylilies it is a precaution, not a sourced requirement). Eat in moderation: a source says to limit quantity or frequency (for example oxalates in sorrels and dock, ginkgotoxin, safrole). Spray risk: a source says the plant is commonly treated with herbicide in parks or lawns (invasive control, lawn weeds) or, for ginkgo, sprayed to stop fruiting. Contamination: a source says the plant concentrates pollutants. Each plant’s Safety flags list gives the details and sources.

Seasons

Start, peak and end are given in thirds of a month: early, mid or late. A plant counts as in season for a month if it is in season at any point in that month. Some greens and roots have a second window, in spring or fall; their page shows each window. A season that runs across New Year is shown as one window.

What it looks like

The tiny, glossy, dark reddish-brown to black seeds of redroot pigweed, each released when a small bladder-like capsule splits around the middle at maturity (NC State); they are no larger than 0.05 inch, oval and flattened (Cornell). They form in dense, stiff flower clusters at the stem tips and in the leaf joints (Cornell), whose spine-like bracts make the plant prickly when mature (US Forest Service), and one plant can produce as many as 117,000 seeds (NC State). Nature’s Restaurant calls the black seeds nutty tasting and very high in protein, and the US Forest Service gives 18 percent protein for seeds with their hulls. Smooth pigweed, which is very hard to tell from redroot pigweed (Rutgers), has edible seeds too (Eat The Weeds).

Safety

NC State calls the seeds edible raw or cooked and does not list them among the poisonous parts; it rates the leaves and stems as poisonous at high severity, explaining that pigweeds build up nitrates that poison grazing animals. Because pigweed concentrates nitrates, the US Forest Service advises using it in moderation, particularly from nitrate-fertilized areas. Eat The Weeds, a foraging site, suggests soaking the seeds overnight to reduce their soap-like saponins; no safety source checked confirms this. The chaff is the main hazard: the flower clusters have stiff, spine-like bracts (US Forest Service), and Nature’s Restaurant warns that the chaff gets into the skin and is very itchy, so wear thick gloves, and says to winnow out all of it because it catches in the throat. Spiny amaranth, which grows in the same places (Virginia plant atlas), has a pair of sharp spines at the base of each leaf (eOrganic). No toxic lookalike is named for the seed heads; Palmer amaranth and prince’s feather, which NC State says are often confused with redroot pigweed, also have edible seeds (NC State). Pigweed is a major weed of crop fields and vegetable plantings, where herbicides are used against it (Ohio State), so gather only where you know nothing has been sprayed. Its pollen causes allergic reactions in some people (GROW).

Lookalikes

  • Palmer amaranth Amaranthus palmeri harmless (may be edible)

    NC State says redroot pigweed is often confused with Palmer amaranth. Palmer amaranth’s stems and leaves are mostly smooth and hairless, and its leaf stalks are longer than those of common pigweed (NC State); Cornell adds that its leaves are hairless with white-veined undersides and long stalks. Redroot and smooth pigweed have hairy stems (Rutgers). NC State says Palmer amaranth’s leaves and seeds are eaten. Maryland designates Palmer amaranth a noxious weed, which landowners are required to eradicate or control (Maryland Department of Agriculture).

  • Prince’s feather (a grain amaranth) Amaranthus hypochondriacus harmless (may be edible)

    NC State says redroot pigweed is often confused with prince’s feather, an amaranth often grown as an ornamental for its showy, feathery red flowers and cultivated for its edible leaves and seeds (NC State). Its flower spikes are usually dark red, purple or deep beet-red (NC State), while pigweed’s are green (NC State).

  • Spiny amaranth Amaranthus spinosus harmless (may be edible)

    Cornell lists spiny amaranth as similar to the pigweeds; its stems are grooved, hairless and spiny (Cornell), with a pair of stiff, sharp half-inch spines at the base of each leaf (eOrganic). Its leaves and seeds are edible, but you have to fight the spines (Eat The Weeds).

Safety flags

Safety marks and flags: what this means

Deadly lookalike / Toxic lookalike: a cited source names a lookalike of that danger, recorded near DC (an iNaturalist sighting within 25 km, a DC street tree, or a Smithsonian listing for DC) and looking like the part you eat. Other lookalikes are still listed, marked “not recorded near DC” or as not looking like the part you eat. Deadly means a source says eating it may be fatal or calls it deadly, or NC State rates it high severity with life-threatening symptoms (sources sometimes disagree; for example Virginia creeper). Each plant’s Lookalikes list says how to tell them apart; “harmless (may be edible)” lookalikes are listed so you know a mix-up isn’t dangerous. Cook first: cooking is needed for safety (for daylilies it is a precaution, not a sourced requirement). Eat in moderation: a source says to limit quantity or frequency (for example oxalates in sorrels and dock, ginkgotoxin, safrole). Spray risk: a source says the plant is commonly treated with herbicide in parks or lawns (invasive control, lawn weeds) or, for ginkgo, sprayed to stop fruiting. Contamination: a source says the plant concentrates pollutants. Each plant’s Safety flags list gives the details and sources.

ID risk
Beginner
Why
No toxic lookalike is named for the seed heads: the University of Wisconsin pairs eastern black nightshade with pigweed only at the seedling stage. Palmer amaranth and prince’s feather, which NC State says are often confused with redroot pigweed, and spiny amaranth also have edible seeds (NC State; Eat The Weeds).
Handling hazards
Thorns (minor)
Soil risk
low
ID risk: what this means

How hard it is to harvest safely. Beginner: no dangerous lookalike, and the edible part is not easily confused with a toxic part. Careful: a toxic lookalike, or toxic parts that end up in the harvest unless removed (for example elderberry stems, unripe ground cherries), or other parts of the plant rated medium-or-higher toxicity, with reliable features to separate them. Expert only: a potentially deadly lookalike that is hard to separate, or (for not-recommended harvests like pokeweed) a plant whose safe preparation can’t be guaranteed. Toxic parts that are obviously separate and thrown away anyway (pits, seeds, skins) don’t raise it; the Toxic parts mark carries that warning.

Handling hazards: what this means

Stings, thorns, irritating or phototoxic sap, staining hulls and spiny husks, with a severity: minor = brief discomfort; moderate = rash or blisters lasting days; serious = burns, scarring or medical care possible.

Soil risk: what this means

Based on the part you eat, following the urban-soil lead guidance on the Field safety page: higher for greens, shoots and roots; moderate for flowers; low for fruit, nuts and sap.

Field safety for every outing (poison ivy, ticks, soil, and more)

When to pick

Starts
early Aug
Peak
early Sep–late Sep
Ends
late Oct

NC State (North Carolina) says the seeds ripen from August through October, and eOrganic says most seed is produced in late summer and early fall; Nature’s Restaurant gives late summer and early fall for the grain. Gather only after a few dry days, when shiny black seeds fall onto a sheet of white paper shaken under a bent seed head (Nature’s Restaurant). The plants die with the fall frost (eOrganic). No source gives dates for the DC area, and the best month is an estimate.

How the dates were worked out

Every start, peak and end was re-checked in October 2026. “Sourced” means a source opened during the check states that timing for the DC or Mid-Atlantic area. “Estimated” means no source states it exactly; the reason, the evidence and the source links are under “How the dates were worked out” on each plant’s page. Peaks are often estimated, because few sources name a peak. iNaturalist evidence means research-grade sightings near DC, by month, of the plant at that stage (for example, in fruit). iNaturalist is a website and phone app where people post photos of the plants and animals they see. A sighting is “research grade” when other users have confirmed what it is; “needs ID” sightings are not confirmed yet, and “cultivated” ones are marked as planted.

Season basis: estimated: peak

Start

sourced

Peak

estimated: No source names a best month; September is the late summer and early fall that all three give for ripe seed.

End

sourced

Evidence

start: NC State (North Carolina): 'It will flower from July through September, the seeds ripen from August through October.' eOrganic: 'Although most seed production occurs in late summer and early fall, some mature seeds have been found in smooth pigweed seed heads at the summer solstice in Virginia (personal observation).' | peak: eOrganic: 'most seed production occurs in late summer and early fall'. US Forest Service (FEIS): 'Rough pigweed normally begins growth in late spring and matures in late summer or early fall'. Nature’s Restaurant: 'Grain: Late Summer & Early Fall'. | end: NC State: 'the seeds ripen from August through October.' eOrganic: the plants 'die with the fall frost.' Rutgers (New Jersey): 'Flowering will start mid-summer and continue through the first frost.'

Where to look

Sunny, disturbed ground: garden beds, field edges, vacant lots and waste places. It is logged only about 30 times near DC and no more than twice in any one place (twice in Rock Creek Park, where picking is not allowed); the C&O Canal and Virginia state parks may or may not count its seeds as allowed fruits or nuts (ask the park first), so the sure option is your own garden or private land with the owner’s permission, away from sprayed fields.

Habitats
disturbed ground & waste places, vacant lots, old fields & meadows
Habitats: what this means

Listed where the plant’s own sources place it in that habitat. “Disturbed ground & waste places” means a cited source places it on disturbed areas, sites, soil or ground, on waste places or waste ground, on construction or abandoned building sites (old home sites count), on rubble or in strip mines. When the source gives examples of the disturbed places, at least one example must be of that kind. Examples that do not count: natural or forestry disturbance (treefall gaps, fire, windthrow, flood scour, old riverbanks and creeks, clear-cuts); roadsides, railroads and rights-of-way; and abandoned fields, pastures and farmland, which are “Old fields & meadows”. “Vacant lots” only where a source says vacant or empty lots.

Most-logged places

None of the most-logged places allows picking.

No picking here (1 place)
  • Rock Creek Park

    2 sightings · Legal to pick: no · see them on iNaturalist

    Look but don’t pick: Rock Creek Park’s compendium bans gathering any fruit, nut, berry, seed or greenery.

Most-logged places: what this means

The places with the most research-grade iNaturalist sightings within 25 km of downtown DC (re-counted in October 2026 over every named place, campuses, condominiums and private grounds included), each marked legal to pick or not. A sighting inside several named places counts once, for the smallest of them, but a sighting inside a National Park Service park never counts for a private, campus or unchecked place. iNaturalist shows where people walk and log plants, not true abundance. Private campuses, condominiums, museums, estates and utility land (Pepco’s power-line land near Sligo Creek) are marked “no” (pick only with the owner’s permission); public university campuses, city parks and other places whose picking rules were not checked (county stormwater land, the U.S. Capitol Grounds, Greenbelt’s North Woods, federal facilities such as the National Zoo) are “unknown”. A place needs at least 2 sightings, so plants with very few sightings have no places. At-risk plants (butternut, nannyberry, American chestnut, ramps, riverbank goldenrod) get places like every other plant; each page says why the plant is at risk and gives any advice its sources give. For some places, mostly Rock Creek Park, the iNaturalist map shows more sightings than the count here, because a map link cannot leave out exactly the sightings credited to another place. iNaturalist is a website and phone app where people post photos of the plants and animals they see. A sighting is “research grade” when other users have confirmed what it is; “needs ID” sightings are not confirmed yet, and “cultivated” ones are marked as planted.

Ways to use it

  • eaten raw or toasted, or sprouted (NC State)
  • ground into flour or meal, for example mixed with buckwheat flour for pancakes or with flour in bread (Nature’s Restaurant; NC State; US Forest Service)
  • boiled with other grains into a hot breakfast cereal (Nature’s Restaurant)
  • popped in a hot, dry pan and eaten as a cereal or mixed with honey and formed into small cakes (Nature’s Restaurant)
  • harvest on a dry day: snip the dry seed heads into a pillowcase or bucket, rub them with heavy gloves, then pour the seeds from bucket to bucket in a breeze until all the chaff is gone (Nature’s Restaurant)

Keeping

Store clean, fully dry seeds airtight in a cool, dark place and use within about a year.

Use within
months+
Keeps fresh
Gather only completely dry seed heads (Nature’s Restaurant) and store the cleaned seeds in cool, dry, dark conditions (general guidance for dried foods, NCHFP).
Keeping basis
general guidance for its type

Ways to keep it

  • Dry as researched: dry/dehydrate; canning: n/a (not shelf-canned)

    Gather the seed heads only after a few dry days, rub out the seeds and winnow away all the chaff (Nature’s Restaurant). Store dried foods in cool, dry, dark areas; recommended storage times for dried foods are 4 months to 1 year (general guidance for dried foods, NCHFP).

Canning: what this means

Shelf-stable canning, three levels. Lab-tested: a lab-tested recipe from the National Center for Home Food Preservation (NCHFP) or Oregon State covers this fruit and product, or a generic recipe for its kind (the line says so, for example chokeberry). Extension recipe: a published Extension recipe (University of Alaska Fairbanks, written for Alaska species; University of Maine’s dandelion jelly), or a process that is safe only with a pH meter; follow it exactly, never improvise. No tested recipe: refrigerate or freeze, don’t can. “Hot-bottled syrup” = maple and walnut syrup, which keep when bottled hot at full syrup density. The Canning line names the exact product each source covers, for example “whole berries” or “juice”; a product not named there (such as juice from a berry with only a whole-berry recipe) has no tested recipe.

Keeping basis: what this means

“Specific to this plant” or “general guidance for its type” (for example NCHFP guidance for leafy greens applied to a wild green).

Nutrition

Not researched: in October 2026, only the calendar’s plants of the month and chicory leaves were researched.

Native or not

USDA PLANTS lists both redroot pigweed and smooth pigweed as native to the lower 48 states, and NC State gives central and eastern North America as redroot pigweed’s origin, but NC State says botanists debate whether it is native or introduced in North Carolina, the US Forest Service calls it introduced and native to tropical America, and the Smithsonian’s DC-area checklist marks it naturalized. Neither plant is on the Virginia, Maryland Department of Agriculture or Maryland Invasive Species Council lists; its relative Palmer amaranth is on the Maryland Invasive Species Council list.

Origin
native
Native range
central & eastern North America
Virginia invasive rank
not listed
Maryland invasive status
not listed
Native or not, and the invader stars: what this means

Origin is where the plant comes from: native, non-native, or mixed (the harvest covers both). The stars rate plants on invasive plant lists: ★★★ Virginia DCR “High” or Maryland prohibited invasive · ★★ Virginia “Medium” · ★ Virginia “Low” · ☆ listed only by the Maryland Invasive Species Council or the Mid-Atlantic Plant Invaders guide (advisory) · no stars: native or not listed.

Virginia DCR, Virginia Invasive Plant Species List (effective September 2024), verbatim: "Under the DCR Invasive Species Assessment Protocol, approved by the Virginia Invasive Species Working Group, January 2024, species were ranked as exhibiting high, medium or low levels of invasiveness based on their threat to natural communities and native species. Invasiveness rank is higher for species that: • Alter ecosystem processes, such as succession, hydrology or fire regime. • Are capable of invading undisturbed natural communities. • Cause substantial impacts on rare or vulnerable species or natural communities or high-quality examples of more common communities. • Are found widely distributed and generally abundant where present. • Disperse readily to new areas. • Are difficult to control." The list also states: "The list is for educational purposes only and has no regulatory authority."

Maryland Department of Agriculture, Maryland Prohibited Invasive Plant Law and Regulations page, verbatim: "Plants on the Maryland Prohibited Invasive Plant List may not be added to stock after the effective date and should not be sold after their phase-out period ends."

No official DC invasive plant list was found.

How the ratings were set

Find
Patchy Estimate 75 = 32 research-grade iNaturalist sightings within 25 km + 122 needs-ID sightings counted at 34% (32 of the 95 research-grade Amaranthus sightings here are redroot or smooth pigweed) + 2 'cultivated' (planted) sightings (rule A); that is tier 3 by count (rule B). Rule D does not apply: the Digital Atlas of the Virginia Flora says "Infrequent throughout." of redroot pigweed in Virginia, which is not rare or very infrequent, and the same atlas says smooth pigweed, counted with it, is "Frequent to common throughout." Final tier 3.
Effort
Real work Cut fully dry seed heads into a pillowcase wearing thick gloves, rub them to free the seeds, and winnow over and over until all the chaff is gone; then toast, pop, cook or grind the tiny seeds.
Find: what this means

1 Everywhere · 2 Common in the right habitat · 3 Patchy · 4 Elusive. This is about how much there is, not whether you may pick it. It is based on iNaturalist sightings within 25 km (about 15 miles) of downtown DC, counted on October 3, 2026. The four rules that each plant’s “Find” reason refers to: (A) the estimate is the confirmed sightings, plus the unconfirmed ones (scaled down where the plant has lookalikes in its genus), plus the sightings marked as planted; (B) the tier by estimate: 1,500 or more is tier 1, 250–1,499 tier 2, 50–249 tier 3, under 50 tier 4; (C) tier 1, Everywhere, also needs a source saying the plant is common in lawns, sidewalks, yards or gardens, vacant lots or towns, or at least one DC street tree of it per km of sidewalk, otherwise it is tier 2; (D) if a reliable source says the plant is rare in this region, or that wild plants rarely bear the harvest, only planted sightings count. iNaturalist is a website and phone app where people post photos of the plants and animals they see. A sighting is “research grade” when other users have confirmed what it is; “needs ID” sightings are not confirmed yet, and “cultivated” ones are marked as planted.

Effort: what this means

1 Grab & eat · 2 Quick kitchen prep (under about 30 minutes) · 3 Real work (hours, or cooking needed for safety) · 4 Project (days or equipment). Scored on the simplest worthwhile use; each plant’s page says why.

Sources

32 sources, each linked to the original.

  1. C&O Canal NHP Superintendent’s Compendium, effective September 11, 2026 National Park Service, Chesapeake and Ohio Canal NHPBacks up: picking rules
  2. Rock Creek Park Superintendent’s Compendium National Park ServiceBacks up: picking rules
  3. 4VAC5-30-50. Flowers, plants, minerals, etc. Virginia Law Library (law.lis.virginia.gov)Backs up: picking rules
  4. 36 CFR 2.1 - Preservation of natural, cultural and archeological resources Legal Information Institute, Cornell Law School (text of federal regulation)Backs up: picking rules
  5. Pigweeds (weed profile) Cornell University, College of Agriculture and Life Sciences, Weed ScienceBacks up: description
  6. Amaranthus retroflexus (Redroot Pigweed) NC State Extension Gardener Plant ToolboxBacks up: description, habitat, uses, safety, season, native or invasive status
  7. Amaranth: Grain, Vegetable, Icon (Green Deane) Eat The WeedsBacks up: description, safety, habitat
  8. FS1350: Redroot and Smooth Pigweed Life Cycle Disruptions for Effective Control in Specialty Crops (Melendez) Rutgers Cooperative Extension (New Jersey Agricultural Experiment Station)Backs up: description, season
  9. Amaranthus retroflexus (Walsh, R. A., 1993), Fire Effects Information System USDA Forest Service, Rocky Mountain Research Station, Fire Sciences LaboratoryBacks up: description, uses, safety, season, habitat, native or invasive status
  10. Green Amaranth Leaves & Grain (David G. Mills) Nature’s Restaurant: A Complete Wild Food Guide (Eastern North America)Backs up: description, uses, season, safety, storage, keeping
  11. iNaturalist research-grade observations of Amaranthus retroflexus and A. hybridus within 25 km of downtown DC iNaturalistBacks up: findability
  12. Amaranthus retroflexus L. (Rough Pigweed, Red-root Amaranth) (Digital Atlas of the Virginia Flora) Virginia Botanical Associates (Digital Atlas of the Virginia Flora)Backs up: habitat, findability
  13. Amaranthus hybridus L. (Slender Pigweed, Smooth Pigweed, Green Amaranth) (Digital Atlas of the Virginia Flora) Virginia Botanical Associates (Digital Atlas of the Virginia Flora)Backs up: habitat, findability
  14. Checklist of the Vascular Plants of the Washington-Baltimore Area (Shetler & Orli) Smithsonian Institution, Department of BotanyBacks up: habitat, native or invasive status
  15. Packaging and Storing Dried Foods National Center for Home Food Preservation (University of Georgia)Backs up: keeping
  16. USDA PLANTS Database: Amaranthus retroflexus (AMRE), native status USDA NRCSBacks up: native or invasive status
  17. USDA PLANTS Database: Amaranthus hybridus (AMHY), native status USDA NRCSBacks up: native or invasive status
  18. Virginia Invasive Plant Species List (effective date: September 2024) Virginia Department of Conservation and Recreation, Division of Natural HeritageBacks up: native or invasive status
  19. Maryland Prohibited Invasive Plant Law and Regulations (Maryland Prohibited Invasive Plant List, updated January 2026; additions effective July 15, 2026; 'Next Plants To Be Assessed' 2026-2027) Maryland Department of Agriculture, Plant Protection & Weed ManagementBacks up: native or invasive status
  20. Non-Native Invasive Terrestrial Plant Species in the State of Maryland (updates approved through the April 18, 2024 MISC meeting) Maryland Invasive Species CouncilBacks up: native or invasive status
  21. Plant Invaders of Mid-Atlantic Natural Areas, Field Guide (Swearingen & Fulton, 2022; successor to the NPS/USFWS 5th ed., 2017) Mid-Atlantic Invasive Plant Council / Passiflora Press (hosted by Bugwood/Mid-Atlantic Invaders Tool)Backs up: native or invasive status
  22. Invasive Plants in the District DC Department of Energy & EnvironmentBacks up: native or invasive status
  23. Amaranthus spinosus L. (Spiny Amaranth) (Digital Atlas of the Virginia Flora) Virginia Botanical Associates (Digital Atlas of the Virginia Flora)Backs up: safety
  24. Amaranthus palmeri (Palmer Amaranth) NC State Extension Gardener Plant ToolboxBacks up: safety
  25. Amaranthus hypochondriacus (Prince’s Feather) NC State Extension Gardener Plant ToolboxBacks up: safety
  26. The Pigweed family identification guide (ANR-0077) Ohio State University Extension (Ohioline)Backs up: safety
  27. Redroot Pigweed (toxic plants) Purdue University, Department of Animal SciencesBacks up: safety details
  28. Redroot Pigweed (Weeds Identification Gallery) University of California Statewide IPM ProgramBacks up: safety details
  29. Noxious Weed Control (Noxious Weeds in Maryland) Maryland Department of Agriculture, Plant Protection & Weed ManagementBacks up: safety details
  30. Redroot & Smooth Pigweed, Amaranthus retroflexus L. and Amaranthus hybridus L. (Singh, Rubione & Sarangi, 2025) GROW (Getting Rid Of Weeds) factsheet; University of Minnesota and University of DelawareBacks up: safety, habitat
  31. Research-grade observations of redroot and smooth pigweed (Amaranthus retroflexus, A. hybridus) within 25 km of DC, by month (all observations) iNaturalistBacks up: season
  32. Weed Profile: Pigweeds (Amaranthus spp.) (Schonbeck) eOrganic (eXtension; author with the Virginia Association for Biological Farming)Backs up: season, safety