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A Forager’s Year

No. 172

Groundnut

Apios americana

American groundnut, hopniss, Indian potato

Roots, bulbs & tubers tubers (cooked)

Drawing: Britton & Brown, Illustrated Flora (1913)

Sources disagree. University of Missouri Extension says the tubers should not be eaten raw because of toxic protease inhibitors that cooking destroys; the USDA plant guide (describing traditional use) says they were eaten raw, Purdue University’s crop handbook (James Duke) says he enjoyed them raw or cooked, Fernald & Kinsey (1958) say the young tubers may be eaten raw, and a 2008 laboratory study found that boiling destroys only part of the main trypsin inhibitor (14% after 30 minutes, 74% after 2 hours). The safety text follows the extension advice and adds the study’s finding.

Find
Common in the right habitat
Effort
Quick kitchen prep
ID risk
Careful
Origin
native
Safety marks
  • Toxic lookalike
  • Cook first
Uses
  • Cooked vegetable / soup
  • Flour

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: No park we checked allows it. Anywhere else, ask whoever owns or runs the land. 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

A native perennial vine of the bean family that twines 8-16 feet over other plants, with hairy stems and compound leaves of 5-7 untoothed leaflets up to 2 inches long (NC State; Eat The Weeds). From June to August it bears compact clusters of maroon or reddish-brown pea-like flowers (NC State), whose fragrance some liken to cinnamon (University of Missouri). Underground, swellings along thin runners form strings of tubers like beads on a necklace, usually about 2-4 ounces each (University of Missouri). Cooked, mature tubers are like potatoes with a nuttier flavor and finer texture, and have about three times the protein of potatoes (NC State; USDA).

Safety

Always cook the tubers: University of Missouri Extension says not to eat them raw because they contain toxic protease inhibitors, which cooking breaks down. Some sources describe eating them raw (USDA, describing traditional use; Purdue University), and an older field guide says the young tubers may be eaten raw, though their sticky juice coats the teeth and lips (Fernald & Kinsey, 1958); follow the extension advice. A 2008 laboratory study found that the tubers' main trypsin inhibitor is unharmed by two hours at 80°C (176°F) and loses only part of its activity in boiling water (14% after 30 minutes, 74% after 2 hours), so cook the tubers thoroughly (Bioscience, Biotechnology, and Biochemistry). Even cooked, a small percentage of people get cramping to severe stomach pain with vomiting and diarrhea, so start with a small portion and eat more only if no symptoms follow (University of Missouri). Eat The Weeds, a foraging site, adds that some people react only after eating groundnuts for years and suspects undercooking or an allergy; no safety source confirms the cause. Toxic lookalike: Japanese and Chinese wisteria, woody vines whose leaves look like groundnut’s (UF/IFAS Extension); NC State lists the roots, seeds and other parts of Chinese wisteria as poisonous. Wisteria has woody stems and 7-13 (Chinese) or 15-19 (Japanese) leaflets per leaf, while groundnut is a twining, non-woody vine with 5-7 leaflets whose runners carry strings of tubers (NC State; Purdue University; University of Missouri). Harmless lookalike: eastern milkpea, which NC State lists as not edible, has three leaflets per leaf and pink or white flowers and grows in dry pine or oak woods; groundnut has 5-7 leaflets and maroon flowers in wet places (NC State; Eat The Weeds). Nature’s Restaurant, a foraging site, warns that groundnut’s compound leaves can look like those of poison sumac, which grows in the same wet places and causes a blistering rash on contact; poison sumac is an upright shrub or small tree with 7-13 leaflets on red leaf stalks (NC State). Poison ivy likes the same wet thickets (Eat The Weeds).

Lookalikes

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
Careful
Why
Toxic lookalike: Japanese and Chinese wisteria, woody vines whose leaves look like groundnut’s (UF/IFAS Extension) and whose roots, seeds and other parts are poisonous (NC State; National Capital Poison Center), so tracing the wrong vine would mean digging poisonous roots. Wisteria has woody stems and 7-13 or 15-19 leaflets; groundnut is a twining, non-woody vine with 5-7 leaflets, and tracing it down to its strings of tubers confirms it (NC State; Purdue University; University of Missouri). Eastern milkpea, a vine NC State lists as not edible, has three leaflets and pink or white flowers in dry woods (NC State; Eat The Weeds). Poison sumac, which a foraging site says can look similar, is an upright shrub with 7-13 leaflets and causes a rash on contact (Nature’s Restaurant; NC State).
Handling hazards
Irritant sap/pulp (moderate)
Soil risk
higher
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 Sep
Peak
early Nov–late Feb
Ends
late Mar

Groundnut tubers can be dug at any time of year when the ground is not frozen (Purdue University; Eat The Weeds), but they are best from late fall through early spring (USDA). An older field guide gives the season as throughout the year, but best from late summer to spring (Fernald & Kinsey, 1958). Waiting until frost has hit the tops tends to make the tubers taste sweeter (University of Missouri). Find the vines while they are still visible: around DC groundnut is logged mostly from June to October and flowers mainly in July and August (iNaturalist). The tubers take about two years to mature (University of Missouri). No source gives dates for the DC area, so all three boundaries are estimates.

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: start, peak, end

Start

estimated: No source dates the start of the dig for the DC area, and the tubers can be dug at any time of year; early September is set as the start because Fernald & Kinsey’s best season begins in late summer and the vines that show where to dig are still easy to find then (iNaturalist), ahead of USDA’s best season from late fall.

Peak

estimated: No source names a best month for the DC area; November through February is USDA’s late fall to early spring, after the first freezes that University of Missouri says sweeten the tubers.

End

estimated: Late March is the end of USDA’s early spring; no DC-area source gives an end date. Digging is possible later in the year (Purdue University), but the window keeps to USDA’s best season.

Evidence

start: Purdue University (James Duke, Handbook of Energy Crops): 'Once large enough, they can be dug at any time of the year when the ground is not frozen.' USDA plant guide: 'The tubers were gathered all year but were best when harvested from late fall through early spring.' Eat The Weeds: 'They can be dug any time of year'. iNaturalist DC sightings (vine visible): Aug 349, Sep 36, Oct 15, Nov 1. Fernald & Kinsey (1958): 'SEASON OF AVAILABILITY: throughout the year, but best from late summer to spring.' | peak: USDA plant guide: best 'from late fall through early spring'. University of Missouri: 'Waiting until the top of the plant is exposed to freezing temperatures tends to cause the tubers of groundnut to taste sweeter.' Eat The Weeds, quoting Purdue’s 1990 new-crops proceedings: 'Tubers are harvested after frost.' | end: USDA plant guide: best 'from late fall through early spring'. Purdue University: they 'can be dug at any time of the year when the ground is not frozen'. iNaturalist DC sightings rise again from May (May 14, Jun 36) as new vines grow.

Where to look

Wet thickets, marsh edges and floodplains, logged most at Kenilworth Park & Aquatic Gardens, Theodore Roosevelt Island, Dyke Marsh, Huntley Meadows and Piscataway Park, where digging is not allowed; dig only on private land with the owner’s permission, and never take all the tubers.

Habitats
old fields & meadows, woods edges, trailsides & thickets, floodplain & stream-valley forest, wetlands, marshes & pond edges
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 (5 places)
  • Kenilworth Park & Aquatic Gardens

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

    Look but don’t pick: Kenilworth is a NACE site that is not on the compendium’s list of gathering areas.

  • Theodore Roosevelt Island

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

    Look but don’t pick: GW Memorial Parkway sites (incl. Great Falls VA, Theodore Roosevelt Island, Dyke Marsh) designate nothing for gathering.

  • Dyke Marsh Wildlife Preserve

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

    Look but don’t pick: GW Memorial Parkway sites (incl. Great Falls VA, Theodore Roosevelt Island, Dyke Marsh) designate nothing for gathering.

  • Huntley Meadows Park

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

    Look but don’t pick: Fairfax County parks ban removing any plant part without written permission.

  • Piscataway Park

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

    Look but don’t pick: a NACE gathering site, but this item is not on the compendium’s list.

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

  • boiled, fried or baked (University of Missouri)
  • in soups and stews, or fried like potatoes (Lady Bird Johnson Wildflower Center)
  • boiled first, then sliced and fried; best eaten hot, since their texture and flavor fade as they cool (Eat The Weeds)
  • roasted, or parboiled with salt and then roasted, which removes the sticky juice that coats the teeth and lips (Fernald & Kinsey, 1958)
  • boiled, then roasted and ground into flour (Eat The Weeds)
  • harvest by digging up a section of runners and pulling the tubers off them; leave some so the plant comes back (University of Missouri)

Keeping

Groundnut tubers keep several months in cool, dry storage (University of Missouri); traditionally they were also boiled, peeled and dried (USDA).

Use within
months+
Keeps fresh
University of Missouri: harvested tubers keep for several months in cool, dry conditions. They can also be dug at any time of year, so they can stay in the ground until needed (Eat The Weeds).
Keeping basis
specific to this plant

Ways to keep it

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

    Traditionally some tubers were boiled, peeled and dried for storage (USDA plant guide, describing Native American use); Eat The Weeds grinds boiled, then roasted tubers into flour.

  • Store whole as researched: root cellar; canning: n/a (not shelf-canned)

    University of Missouri: harvested tubers have a storage life of several months under cool, dry conditions.

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

Origin
native
Native range
eastern & central North America (southern Canada to Florida, west to Colorado)
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
Common in the right habitat Estimate 578 = 511 research-grade iNaturalist sightings within 25 km + 64 needs-ID sightings counted in full (American groundnut is the only Apios with research-grade sightings here) + 3 'cultivated' (planted) sightings (rule A); that is tier 2 by count (rule B). Rule D does not apply: the DC Department of Energy & Environment’s draft 2025 Wildlife Action Plan says "Tier I SGCN are rare species that are known to be present in the District" and lists American groundnut as Tier I, but the Digital Atlas of the Virginia Flora, a source of equal standing about Virginia, calls it "Frequent throughout". Final tier 2.
Effort
Quick kitchen prep Dig along the runners where the vine enters the ground, pull off the tubers, scrub them and cook them through by boiling, baking or frying.
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

27 sources, each linked to the original.

  1. Rock Creek Park Superintendent’s Compendium National Park ServiceBacks up: picking rules
  2. 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
  3. Apios americana (American Groundnut, Common Groundnut, Hopniss, Indian Potato, Potato Bean) NC State Extension Gardener Plant ToolboxBacks up: description, habitat, native or invasive status
  4. iNaturalist research-grade observations of Apios americana within 25 km of downtown DC iNaturalistBacks up: findability
  5. District of Columbia Wildlife Action Plan, Draft 2025 Update, Chapter 4: Species of Greatest Conservation Need DC Department of Energy & EnvironmentBacks up: findability
  6. Annotated Checklist of the Vascular Plants of the Washington-Baltimore Area, Part I (Shetler & Orli, 2000) Smithsonian Institution, National Museum of Natural History, Department of BotanyBacks up: habitat
  7. Apios americana (Groundnut) (Digital Atlas of the Virginia Flora) Virginia Botanical Associates (Digital Atlas of the Virginia Flora)Backs up: habitat, findability
  8. USDA PLANTS Database: Apios americana (APAM), native status USDA NRCSBacks up: native or invasive status
  9. Virginia Invasive Plant Species List (effective date: September 2024) Virginia Department of Conservation and Recreation, Division of Natural HeritageBacks up: native or invasive status
  10. 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
  11. 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
  12. 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
  13. Invasive Plants in the District DC Department of Energy & EnvironmentBacks up: native or invasive status
  14. Galactia regularis (Eastern Milkpea) NC State Extension Gardener Plant ToolboxBacks up: safety
  15. Q: I found these pea pods growing on a vine in my back yard. Can I eat them? (2017) UF/IFAS Extension Nassau CountyBacks up: safety
  16. Wisteria floribunda (Japanese Wisteria) NC State Extension Gardener Plant ToolboxBacks up: safety
  17. Wisteria sinensis (Chinese Wisteria) NC State Extension Gardener Plant ToolboxBacks up: safety
  18. Virginia Creeper and Wisteria Toxicity National Capital Poison Center (Poison Control)Backs up: safety
  19. Toxicodendron vernix (Poison Sumac) NC State Extension Gardener Plant ToolboxBacks up: safety
  20. Groundnut (Hopniss) Nature’s Restaurant (foraging site)Backs up: safety
  21. Purification, Characterization, and cDNA Cloning of a Bowman-Birk Type Trypsin Inhibitor from Apios americana Medikus Tubers (Zhang et al., Biosci. Biotechnol. Biochem. 72(1), 2008) Japan Society for Bioscience, Biotechnology, and Agrochemistry (J-STAGE)Backs up: safety
  22. The Incredible Groundnut (David Trinklein, Missouri Environment and Garden, January 10, 2020) University of Missouri Extension, Integrated Pest ManagementBacks up: safety, season, uses, description, picking rules, storage, keeping
  23. iNaturalist research-grade observations of Apios americana within 25 km of Washington, DC, by month (all observations, flowering, fruiting) iNaturalistBacks up: season
  24. Groundnut, Apios americana Medik. (Plant Guide) USDA NRCS National Plant Data CenterBacks up: season, habitat, description, storage, keeping
  25. Apios americana Medik. (James A. Duke, Handbook of Energy Crops, 1983) Purdue University, Center for New Crops & Plant Products (NewCROP)Backs up: season, safety, habitat
  26. Groundnuts: Anti-Cancer Treat (Green Deane) Eat The WeedsBacks up: season, uses, safety, description, habitat, keeping
  27. Apios americana (Groundnut, Wild Potato, Indian Potato) Lady Bird Johnson Wildflower CenterBacks up: uses, habitat