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A Forager’s Year

No. 139

American hornbeam

Carpinus caroliniana

musclewood, ironwood, blue beech

Nut & seed ripe nutlets (rubbed free of their papery bracts)

Drawing: Britton & Brown, Illustrated Flora (1913)

Find
Common in the right habitat
Effort
Quick kitchen prep
ID risk
Beginner
Origin
native
Uses
  • Eat raw / salad
  • 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.

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 small native understory tree of the birch family whose smooth, bluish-gray bark is stretched over a ridged, fluted trunk that looks like flexed muscle (NC State). The fruit is a small, ribbed nutlet about 1/3 inch long, attached to a leaf-like, 3-lobed bract that carries it on the wind (NC State); the nutlets hang in clusters 2 to 4 inches long and turn from green to light greenish brown or brown when ripe (USDA Forest Service). Foraging Texas finds the seeds plentiful and easy to collect, with a mild, nutty flavor raw that roasting improves. Eat The Weeds calls the nutlets neither great nor awful as food, but small, and the USDA Forest Service says the nuts are edible but small and so seldom collected for food. Large crops come every 3 to 5 years (USDA Forest Service).

Safety

No toxicity is reported for the nutlets in the sources checked: NC State lists no poisonous part of American hornbeam and rates its fruit edible, and the USDA Forest Service says the nuts are edible. Eastern hophornbeam, which shares the name ironwood (Smithsonian checklist), is a harmless lookalike: its nutlets are enclosed in dried, leafy, inflated sacs in drooping clusters that somewhat resemble hops, and older trees have rough, grayish-brown bark with loose scaly plates (NC State). NC State also names American beech, planted European hornbeam, river birch, Chinese elm, Japanese zelkova and winged elm as trees often confused with American hornbeam, plus Chinese zelkova, and oriental hornbeam, which is not recorded near DC; of these, only American beech has a poison listing at NC State, a low-severity one for stomach irritation from eating its nuts in quantity, and none bears ribbed nutlets on 3-lobed bracts except European hornbeam, a larger planted tree (NC State).

Lookalikes

  • Eastern hophornbeam Ostrya virginiana harmless (may be edible)

    Hophornbeam’s ribbed 1/4-inch nutlet is enclosed in a dried, leafy, inflated sac, in drooping clusters that somewhat resemble hops, and older trees have rough bark with loose scaly plates (NC State); American hornbeam’s nutlet sits openly on a leaf-like, 3-lobed bract, and its bark stays smooth and bluish-gray over a ridged trunk (NC State). Hophornbeam grows in mesic to dry upland forests and rocky woodlands (Virginia plant atlas). Foraging Texas eats hophornbeam seeds too and lists no dangers.

  • American beech Fagus grandifolia harmless (may be edible)

    Beech also has thin, smooth, gray bark, but its fruit is a prickly husk holding irregularly triangular, shiny brown nuts (NC State), not a ribbed nutlet on a 3-lobed bract. Beechnuts are themselves eaten; NC State says they can irritate the stomach if eaten in quantity.

  • European hornbeam Carpinus betulus harmless (may be edible)

    A planted shade and street tree that grows 40 to 60 feet tall, with a small brown nutlet on a serrated, folded bract (NC State); American hornbeam is a smaller tree, 20 to 30 feet (NC State). The Lady Bird Johnson Wildflower Center says European hornbeam’s trunk is obscured by lower branching. No source checked describes it as food.

  • River birch Betula nigra harmless (may be edible)

    River birch has salmon to rust-colored bark that peels in papery layers, and a 1 to 1 1/2 inch cone-like fruit holding tiny seeds (NC State), not single nutlets on 3-lobed bracts.

  • Chinese elm Ulmus parvifolia harmless (may be edible)

    Chinese elm has mottled bark that flakes off in irregular patches, and its fruit is a flat, papery winged samara about 1/2 inch long (NC State), not a ribbed nutlet on a 3-lobed bract.

  • Japanese zelkova Zelkova serrata harmless (may be edible)

    Zelkova bears a small fruit with two small beaks (NC State), not a ribbed nutlet on a 3-lobed bract.

  • Winged elm Ulmus alata harmless (may be edible)

    NC State lists winged elm as often confused with American hornbeam. Its stems usually carry two wide corky ridges or wings, and its fruit is small, fuzzy and tipped with two long, curving bristles (NC State), not a ribbed nutlet on a 3-lobed bract. NC State lists no poisonous part.

  • Chinese zelkova Zelkova schneideriana harmless (may be edible)

    NC State lists it as often confused with American hornbeam; its fruit is a kidney-bean-shaped drupe (NC State), not a ribbed nutlet on a 3-lobed bract.

  • Oriental hornbeam Carpinus orientalis harmless (may be edible)

    Not recorded near DC. NC State lists it as often confused with American hornbeam; its leaves are smaller, 1 to 2 inches long, and its nutlets carry unlobed bracts (NC State), while American hornbeam’s bracts are 3-lobed.

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. Eastern hophornbeam, which shares the name ironwood (Smithsonian checklist), is harmless and is told apart by its nutlets enclosed in dried, leafy, inflated sacs in drooping, hop-like clusters; American hornbeam’s nutlets sit openly on 3-lobed bracts, under smooth, muscle-like bark (NC State).
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.

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
late Aug
Peak
late Sep–late Oct
Ends
late Nov

The USDA Forest Service says American hornbeam fruits ripen from August to October in the northeastern United States and are shed from November into spring. Eat The Weeds gives late August into winter for the nutlets, and NC State gives fall as the harvest time. Ripe nutlets turn from green to light greenish brown or brown (USDA Forest Service), and the Lady Bird Johnson Wildflower Center says to collect them once the bracts have turned pale greenish brown. Around DC, iNaturalist sightings marked as fruiting run from March to December because green fruit is counted, so they could not shape this season; the latest fall at the turn of November and December. Big crops come only every 3 to 5 years (USDA Forest Service).

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, end

Start

sourced

Peak

estimated: No source names a peak. Late September to late October is the end of the August-October ripening window, when the nutlets have turned brown but before the November start of seed fall; NC State’s fall harvest time agrees. The DC fruiting records include green fruit from spring on and cannot show ripeness.

End

estimated: No regional source names a closing date. Seed fall starts in November, and the last DC fruiting records fall at the turn of November and December; Eat The Weeds' 'to winter' is kept as a caveat in the notes rather than extending the window.

Evidence

start: USDA Forest Service Woody Plant Seed Manual, table 2 (C. caroliniana, NE US): fruit ripening dates August to October. USDA Forest Service (FEIS): 'The fruits ripen from August to October in the same season'. Eat The Weeds: 'nutlets late August to winter'. Lady Bird Johnson Wildflower Center: 'Collect nutlets in late summer or early fall when bracts have turned a pale, greenish-brown.' | peak: Woody Plant Seed Manual (NE US): ripening Aug–Oct, seed dispersal Nov–spring; preripe color green, ripe color greenish brown. NC State: 'Display/Harvest Time: Fall'. iNaturalist, DC, research grade, fruiting annotation, by month: Mar 1, Apr 7, May 21, Jun 21, Jul 11, Aug 21, Sep 8, Oct 5, Nov 4, Dec 1. | end: Woody Plant Seed Manual, table 2 (NE US): seed dispersal dates November to spring. Eat The Weeds: 'nutlets late August to winter'. iNaturalist, DC, research grade, fruiting annotation, by week of year: weeks 44 (2), 45 (1), 46 (1), 48 (1), none later; by month, November 4 and December 1 (the December record falls in week 48).

Where to look

Shaded stream valleys and floodplain woods, plus planted street trees; logged most in Rock Creek Park (no picking) and on the C&O Canal towpath, where the compendium allows edible nuts generally but does not list hornbeam and its nutlets may or may not count as nuts, so it is ambiguous (ask the park first). Virginia state parks are ambiguous too; otherwise pick from private trees with the owner’s permission.

Habitats
street & yard trees (planted), old fields & meadows, floodplain & stream-valley forest, upland oak-hickory woods, 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.

Ask first: rules unclear or not checked

  • C&O Canal NHP (towpath, Georgetown to Great Falls MD and beyond)

    50 sightings · Legal to pick: ambiguous · see them on iNaturalist

    Ambiguous: the C&O compendium allows edible fruits, nuts and berries generally but sets no limit for this one; ask the park first. Of these, 6 are at Carderock.

No picking here (4 places)
  • Rock Creek Park

    69 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.

  • Glencarlyn Park

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

    Look but don’t pick: Arlington County park rules say flora shall not be removed or disturbed.

  • Rock Creek Regional Park (MD)

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

    Look but don’t pick: Montgomery/Prince George’s parks (M-NCPPC) ban harvesting vegetation without a permit.

  • Sligo Creek Stream Valley Park

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

    Look but don’t pick: Montgomery/Prince George’s parks (M-NCPPC) ban harvesting vegetation without a permit.

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

  • eat raw: the seeds have a mild, nutty flavor (Foraging Texas)
  • roasted: roasting them a bit makes them taste even better (Foraging Texas; Eat The Weeds)
  • porridge: boil the raw or roasted seeds (Foraging Texas)
  • flour: grind the nutlets and add them to other flours or foods (Foraging Texas; Eat The Weeds)
  • harvest by rubbing the papery bracts between your hands to free the nutlets (Eat The Weeds); for a larger batch, spread the clusters on screens to dry, then beat them inside a bag to separate the seeds from the chaff (Lady Bird Johnson Wildflower Center)

Keeping

Rub off the bracts, dry the nutlets soon after gathering and store them cool and airtight.

Use within
months+
Keeps fresh
Start drying soon after gathering, usually within 24 hours, in a single layer at 90 to 100°F; nuts dried and stored in the shell keep several months at room temperature, and roasted nuts and seeds should be eaten within 2 to 3 weeks (general guidance for nuts, WSU).
Keeping basis
general guidance for its type

Ways to keep it

  • Dry as researched: roast & store; canning: n/a (not shelf-canned)

    Roasted nuts and seeds have a shorter shelf life than dried ones; eat them within 2 to 3 weeks (general guidance for nuts, WSU).

  • Store whole as researched: store in shell; canning: n/a (not shelf-canned)

    Once dry, keep the nutlets in airtight containers below 70°F; the cooler the storage, the longer they keep (general guidance for nuts, WSU).

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 North America; also central and southern Mexico and Central 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
Common in the right habitat Estimate 1,828 = 913 research-grade iNaturalist sightings within 25 km + 814 needs-ID sightings counted in full (American hornbeam is the only Carpinus with research-grade sightings here) + 101 'cultivated' (planted) sightings (rule A); that is tier 1 by count (rule B). Rule C: none of its sources says it is common in, or a weed of, an everyday place (lawns, sidewalks, yards or gardens, vacant lots, towns), and DC’s street-tree inventory lists 1,698 living American hornbeams, under the line of one per km of DC sidewalk (2,406), so it cannot be tier 1 (Everywhere). Final tier 2.
Effort
Quick kitchen prep Pull the nutlets from the hanging clusters, rub off the papery bracts between your hands, and eat them raw or lightly roasted; grinding enough tiny nutlets for flour or porridge is a 3.
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

37 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 (2026) 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. Maryland man fined $50 for picking berries ReasonBacks up: picking rules
  6. American hornbeam (Silvics of North America) USDA Forest ServiceBacks up: description, habitat, picking rules, native or invasive status
  7. Carpinus caroliniana (American Hornbeam) NC State Extension Gardener Plant ToolboxBacks up: description, season, habitat, safety, native or invasive status
  8. Carpinus caroliniana (Fire Effects Information System species review) USDA Forest ServiceBacks up: description, season, safety
  9. Musclewood Foraging Texas (Mark Vorderbruggen)Backs up: description, uses
  10. Hornbeam, Ironwood, Blue Beech (Green Deane) Eat The WeedsBacks up: description, uses, season, keeping
  11. iNaturalist research-grade observations of Carpinus caroliniana within 25 km of downtown DC iNaturalistBacks up: findability
  12. Carpinus caroliniana Walt. (American Hornbeam, Ironwood) Digital Atlas of the Virginia Flora (Virginia Botanical Associates)Backs up: habitat
  13. Tuliptree Small-Stream Floodplain Forest at Rock Creek Park: plants and animals Explore Natural Communities (NatureServe with the National Park Service)Backs up: habitat
  14. DC street-tree inventory (DDOT Urban Forestry, UFA Street Trees layer): living trees by species, queried 2026-10-05 (1,698 living American hornbeams) District of Columbia (DDOT Urban Forestry Division, via DC GIS)Backs up: habitat, findability
  15. 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, safety
  16. USDA PLANTS Database: Carpinus caroliniana (CACA18), native status USDA NRCSBacks up: native or invasive status
  17. Virginia Invasive Plant Species List (effective date: September 2024) Virginia Department of Conservation and Recreation, Division of Natural HeritageBacks up: native or invasive status
  18. 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
  19. 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
  20. 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
  21. Invasive Plants in the District DC Department of Energy & EnvironmentBacks up: native or invasive status
  22. Eastern hop-hornbeam (Ostrya virginiana) NC State Extension Gardener Plant ToolboxBacks up: safety
  23. Fagus grandifolia (American beech) NC State Extension Gardener Plant ToolboxBacks up: safety details
  24. Carpinus betulus (European hornbeam) NC State Extension Gardener Plant ToolboxBacks up: safety details
  25. Betula nigra (river birch) NC State Extension Gardener Plant ToolboxBacks up: safety details
  26. Ulmus parvifolia (Chinese elm) NC State Extension Gardener Plant ToolboxBacks up: safety details
  27. Zelkova serrata (Japanese zelkova) NC State Extension Gardener Plant ToolboxBacks up: safety details
  28. Ostrya virginiana (Hop-hornbeam, Eastern Hop-hornbeam, Ironwood) Digital Atlas of the Virginia Flora (Virginia Botanical Associates)Backs up: safety details
  29. Hop Hornbeam Foraging Texas (Mark Vorderbruggen)Backs up: safety details
  30. Ulmus alata (winged elm) NC State Extension Gardener Plant ToolboxBacks up: safety details
  31. Zelkova schneideriana (Chinese zelkova) NC State Extension Gardener Plant ToolboxBacks up: safety details
  32. Carpinus orientalis (oriental hornbeam) NC State Extension Gardener Plant ToolboxBacks up: safety details
  33. Carpinus L., hornbeam (Woody Plant Seed Manual, Agriculture Handbook 727) USDA Forest ServiceBacks up: season
  34. American hornbeam research-grade observations within 25 km of DC, by week of year (fruiting annotation) iNaturalistBacks up: season
  35. American hornbeam research-grade observations within 25 km of DC, by month (fruiting annotation) iNaturalistBacks up: season
  36. Carpinus caroliniana (American hornbeam, blue beech) Lady Bird Johnson Wildflower Center (University of Texas at Austin)Backs up: season, habitat, uses
  37. Food Safety and Preservation: Nuts & Seeds Washington State University Extension, Lewis CountyBacks up: storage, keeping