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A Forager’s Year

No. 169

Cattail

Typha latifolia (also T. angustifolia)

Roots, bulbs & tubers rhizomes (starchy rootstocks, cooked)

Drawing: Britton & Brown, Illustrated Flora (1913)

Find
Common in the right habitat
Effort
Real work
ID risk
Careful
Origin
native
Safety marks
  • Toxic lookalike
  • Cook first
  • Spray risk
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

The underground stems (rhizomes) of cattail, the tall marsh plant whose stalks are topped with brown, sausage-shaped flowering heads (USDA). They grow horizontally just below the soil surface and are tough and stout, up to about 28 inches long and 0.2 to 1.2 inches thick, soft and spongy with internal air spaces (US Forest Service). They are fairly high in starch, usually listed at 30% to 46%, and have a sweet flavor (USDA). Native Americans ground the rootstock into meal, and early colonists also ate it (Lady Bird Johnson Wildflower Center). Cooked, a rhizome is eaten like an artichoke leaf: the starch is stripped from the fibers with the teeth (Farmers' Almanac).

Safety

Cook the rhizomes: CDC says people most often catch the Fasciola liver fluke by eating raw watercress or other freshwater plants, although NC State and USDA say the rhizomes can be eaten raw. Toxic lookalikes: blue flag iris (native) and yellow flag iris (invasive in Virginia) grow in the same marshes, and iris is toxic, with the toxin most concentrated in the rhizome, the very part dug here (NC State). Sweet flag can also look like a cattail stand (US Forest Service); the Eurasian sweet flag contains beta-asarone, which the European Medicines Agency says causes liver cancer in rodents, and US law bans adding calamus, its dried rhizome, to food (US Food and Drug Administration). Dig only where brown cattail seed heads still stand on their stalks, as they usually do through winter (US Forest Service); iris never forms that brown spike (Farmers' Almanac), and sweet flag has only a small greenish finger-like flower spike (US Forest Service; NC State). Cattails are round at the base, while yellow flag iris leaves are flattened along one plane and clasp the stem at the base in a fan (Oregon State University; Washington State Noxious Weed Control Board). Yellow flag iris rhizomes have black sap (Montana Department of Agriculture), and sweet flag leaves and rhizomes smell sweet when crushed (NC State), while cattail is mild and has little smell (Eat The Weeds). Flowering rush, which looks similar to cattails (Government of Alberta), is not recorded near DC; its leaves are triangular in cross section (Montana Department of Agriculture). Yellow flag iris sap can irritate or blister the skin (Oregon State University). Cattails take up pollutants, and in urban stormwater wetlands the rhizome holds the largest share of the heavy metals in the plant (Resources, Conservation and Recycling, 1994), so never dig in roadside ditches, farm runoff areas, industrial sites or polluted urban waterways (Farmers' Almanac); Virginia Cooperative Extension says to harvest aquatic plants only from a clean water source. Virginia’s Department of Wildlife Resources lists herbicides for treating cattails in ponds, so ask the owner about spraying before digging. Eat The Weeds, a foraging site, says raw starch and the fibers gave its author a stomach ache; no safety source confirms this, and spitting out the fibers of the cooked rhizome is the usual way to eat it. Virginia Cooperative Extension advises never harvesting aquatic plants alone and wearing boots or waders and a life vest.

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 blue flag and yellow flag iris grow in the same marshes and are most toxic in the rhizome (NC State), and Eurasian sweet flag, whose rhizome is banned from US food, can look like a cattail stand (US Forest Service; US Food and Drug Administration). Dig only where brown cattail spikes still stand on the stalks, which neither iris nor sweet flag forms (Farmers' Almanac; US Forest Service); cattails are also round at the base where iris is fan-shaped (Oregon State University; Washington State Noxious Weed Control Board), sweet flag smells sweet when crushed (NC State), and yellow flag iris rhizomes have black sap (Montana Department of Agriculture). Flowering rush, which looks similar, is not recorded near DC (Government of Alberta; Montana Department of Agriculture).
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 Oct
Peak
early Nov–late Feb
Ends
late Apr

Cattail rhizomes can be dug at any time of year but are best in fall and winter (Farmers' Almanac). Virginia Cooperative Extension says they are harvested from fall to spring, and the US Forest Service says Native Americans dug and ate them in fall and winter. Virginia Cooperative Extension and Eat The Weeds also praise the roots in spring. No source gives dates for the DC area, so these dates are estimates. In winter the brown seed heads usually stay on their stalks (US Forest Service), which helps confirm a cattail stand before digging.

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 for the DC area; early October is the start of the fall dig that Virginia Cooperative Extension and the US Forest Service describe, as the leaves yellow and the plants die back.

Peak

estimated: No source names a best month for the DC area, and sources differ: Farmers' Almanac calls fall and winter best and the US Forest Service gives fall and winter for traditional digging, while Virginia Cooperative Extension calls spring best. November through February follows the fall-and-winter sources; spring stays inside the window to late April.

End

estimated: No source gives an end date; late April keeps the spring digging that Virginia Cooperative Extension and Eat The Weeds describe, while new shoots are coming up from the rhizomes.

Evidence

start: Virginia Cooperative Extension: 'These are harvested from fall to spring.' US Forest Service (FEIS): 'Rhizomes were dug and eaten in the fall and winter.' and, for the Midwest, cattails 'senescence before late October'. NC State: 'Leaves turn bright yellow in fall.' | peak: Farmers' Almanac: 'The roots (called rhizomes) are harvestable throughout the year, but they’re best in the fall and winter .' US Forest Service (FEIS): 'Rhizomes were dug and eaten in the fall and winter.' Virginia Cooperative Extension: 'The best time to collect cattails is during the spring when roots and stems are at their best.' | end: Virginia Cooperative Extension: harvested 'from fall to spring' and 'The best time to collect cattails is during the spring when roots and stems are at their best.' Eat The Weeds: 'bottoms of stalks and root year best in fall and spring.' US Forest Service (FEIS), Midwest: 'cattails usually emerge by early April'.

Where to look

Freshwater marshes and pond edges; Kenilworth Aquatic Gardens, Theodore Roosevelt Island and Huntley Meadows have the most logged stands but ban picking, so dig only on private land with the owner’s permission, in clean water away from roads and stormwater runoff.

Habitats
disturbed ground & waste places, 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

    57 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

    43 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

    26 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.

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

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

    Look but don’t pick: the C&O Canal compendium covers only edible fruits, nuts, berries and mushrooms, and NPS parks can never designate leaves, flowers, roots or sap.

  • Glenstone Museum grounds (private)

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

    Private property: pick only with the owner’s permission.

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

  • roasted, baked or boiled until tender, then eaten like an artichoke leaf, stripping the starch from the fibers with the teeth (Farmers' Almanac)
  • baked, roasted or broiled (NC State; USDA)
  • dried and pounded into flour, with the fibers removed, and used as a thickener (Virginia Cooperative Extension; Farmers' Almanac)
  • crushed in clean water so the starch settles out, then used like any flour (Eat The Weeds)
  • roasted, dried roots simmered as the base of a salmon chowder (Indiana Department of Natural Resources recipe, Farmers' Almanac)
  • the buds attached to the rhizomes are also edible (Farmers' Almanac)

Keeping

Keep cold and moist and use within a few weeks, or dry them and pound them into flour.

Use within
weeks
Keeps fresh
Keep the rhizomes cold and moist, for example in perforated plastic bags in the refrigerator (general guidance for root vegetables; University of Minnesota). Eat The Weeds says that, like most roots, they can be stored for a while, and Farmers' Almanac notes they can be dug at any time of year, so they can stay in the ground until needed.
Keeping basis
general guidance for its type

Ways to keep it

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

    For flour: scrape and clean the rhizomes, dry them overnight on a lightly greased cookie sheet in a 200°F oven, skin them and remove the fibers, pound them fine, let the flour dry overnight and sift it (Farmers' Almanac). Peel the roots while they are wet; they are hard to peel once dry (Eat The Weeds). Store dried foods in airtight containers in a cool, dry, dark place and check them for moisture; NCHFP gives 4 months to 1 year for dried foods, with vegetables keeping about half as long as fruits.

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

T. latifolia is native. USDA PLANTS lists narrowleaf cattail (T. angustifolia) as both native and introduced in the lower 48; its status in the Mid-Atlantic is debated (often treated as introduced from Europe), and it hybridizes with T. latifolia (T. x glauca). None of the cattails is on VA DCR, MDA or MISC lists.

Origin
native
Native range
Typha latifolia: N. & S. America, Europe, Eurasia and Africa (per NC State)
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 1,593 = 373 research-grade iNaturalist sightings within 25 km + 1,191 needs-ID sightings counted in full (the harvest is the whole genus) + 29 '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), so it cannot be tier 1 (Everywhere). Of the 373 research-grade sightings, 80 are narrowleaf cattail (T. angustifolia, often treated as introduced), 3 hybrid cattail and 2 the Asian ornamental T. laxmannii. Final tier 2.
Effort
Real work Dig the rhizomes out of the wet ground, clean them and trim off the small roots, then roast, bake or boil them until tender and chew the starch off the fibers; drying and pounding them into flour, or washing out the starch, is also 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. 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. Typha latifolia (Common cattail) Lady Bird Johnson Wildflower CenterBacks up: description
  4. Typha latifolia (Broadleaf Cattail) NC State Extension Gardener Plant ToolboxBacks up: description, habitat, uses, safety, season, native or invasive status
  5. Plant Guide: Broad-leaved Cattail, Typha latifolia USDA NRCS National Plant Data Center & Idaho Plant Materials CenterBacks up: description, uses, safety
  6. iNaturalist research-grade observations of Typha (genus) within 25 km of downtown DC iNaturalistBacks up: findability
  7. Typha latifolia L. (Common Cattail, Broadleaf Cattail) (Digital Atlas of the Virginia Flora) Virginia Botanical Associates (Digital Atlas of the Virginia Flora)Backs up: habitat
  8. Harvesting and storing home garden vegetables University of Minnesota ExtensionBacks up: keeping
  9. Packaging and Storing Dried Foods National Center for Home Food Preservation (University of Georgia)Backs up: keeping
  10. USDA PLANTS Database: Typha latifolia (TYLA), native status USDA NRCSBacks up: native or invasive status
  11. USDA PLANTS Database: Typha angustifolia (TYAN), native status USDA NRCSBacks up: native or invasive status
  12. NC State Extension Gardener Plant Toolbox: Typha angustifolia (Country or Region of Origin) North Carolina State University ExtensionBacks up: native or invasive status
  13. Virginia Invasive Plant Species List (effective date: September 2024) Virginia Department of Conservation and Recreation, Division of Natural HeritageBacks up: native or invasive status
  14. 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
  15. 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
  16. 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
  17. Invasive Plants in the District DC Department of Energy & EnvironmentBacks up: native or invasive status
  18. Iris pseudacorus (Yellow Flag Iris) NC State Extension Gardener Plant ToolboxBacks up: safety
  19. Iris versicolor (Blue Flag Iris) NC State Extension Gardener Plant ToolboxBacks up: safety
  20. Determination of the Toxic Effects of Heavy Metals on the Morpho-Anatomical Responses of the Leaf of Typha latifolia as a Biomonitoring Tool (Plants, 2024) NIH National Library of Medicine (PubMed Central)Backs up: safety details
  21. Acorus calamus (Sweet Flag) NC State Extension Gardener Plant ToolboxBacks up: safety, effort & ID risk, safety details
  22. Sweet Flag (Acorus americanus), Celebrating Wildflowers plant of the week USDA Forest ServiceBacks up: safety, effort & ID risk, safety details
  23. 21 CFR 189.110 Calamus and its derivatives (substances prohibited from use in human food) US Food and Drug Administration (Electronic Code of Federal Regulations)Backs up: safety, effort & ID risk, safety details
  24. Written Findings: Yellow flag (Iris pseudacorus) Washington State Noxious Weed Control BoardBacks up: safety, effort & ID risk, safety details
  25. Yellow flag iris (Solve Pest Problems) Oregon State University Extension ServiceBacks up: safety, effort & ID risk, safety details
  26. Yellowflag Iris (Iris pseudacorus) identification and management guide Montana Department of AgricultureBacks up: safety, effort & ID risk, safety details
  27. Public statement on the use of herbal medicinal products containing asarone (EMEA/HMPC/139215/2005) European Medicines Agency, Committee on Herbal Medicinal ProductsBacks up: safety, safety details
  28. Use of macrophytes for pollution treatment in urban wetlands (Ellis, Shutes, Revitt & Zhang, Resources, Conservation and Recycling 11, 1994), abstract Bournemouth University staff profile (Scopus abstract)Backs up: safety, safety details
  29. Cattails (aquatic plant ID and treatment) Virginia Department of Wildlife ResourcesBacks up: safety, safety details
  30. About Liver Flukes US Centers for Disease Control and PreventionBacks up: safety, safety details
  31. Flowering rush Government of AlbertaBacks up: safety, safety details
  32. Flowering Rush (Butomus umbellatus) Montana Department of AgricultureBacks up: safety, safety details
  33. iNaturalist research-grade observations of Typha (cattails) within 25 km of Washington, DC, by month (all observations) iNaturalistBacks up: season
  34. Typha latifolia (Gucker, C. L., 2008), Fire Effects Information System USDA Forest Service, Rocky Mountain Research Station, Fire Sciences LaboratoryBacks up: season, description, habitat, safety, effort & ID risk, safety details
  35. Edible Aquatic Plants in Farm Ponds (CNRE-127NP; Crosby, Nerrie & Gregg, 2021, reviewed 2026) Virginia Cooperative Extension (Virginia Tech and Virginia State University)Backs up: season, uses, safety
  36. Wild Edible Cattails: 5 Parts You Can Eat (A. Kanuckel) Farmers' AlmanacBacks up: season, uses, safety, description, storage, keeping
  37. Cattails - A Survival Dinner (Green Deane) Eat The WeedsBacks up: season, uses, safety, storage, effort & ID risk, keeping