Common plants of the northern United States and Canada
reported to have caused poisonings, a dermatitis or hay fever in humans

Gerald A. Mulligan (1928 - 2022)
Research Scientist and Research Institute Director (retired).
Honorary Research Associate (1987 - 2022), Agriculture and Agri-Food Canada,
Ottawa, Ontario K1A 0C6, Canada

Awarded the George Lawson Medal by the Canadian Botanical Association in 2006. Awarded the Faculty of Macdonald, McGill University, Most Distinguished Alumni Award on October 18, 2014.
Read his biography "The Real Weed Man" available in print and ebook.
    This publication contains information on the common cultivated, native, and naturalized plants of the northern United States and Canada that are reported to have caused poisonings, a dermatitis or hay fever in humans. Much of  the information given here was obtained during literature searches leading to the  publication Poisonous plants of Canada, Agriculture Canada publication 1842/E, 1990, by Gerald A. Mulligan and Derek B. Munro. The severity of poisonings varies greatly from plant species to plant species, from person to person, and on the parts of the plant eaten. Some toxins are so potent that a single mouthful can cause severe poisoning, whereas others become toxic only after large quantities are consumed or when material is eaten over a long period of time. Plant poisons can cause only a slight discomfort in some cases, to a violent sickness or even death in others, depending on the species ingested and the susceptibility of an individual.  People also differ greatly in their susceptibility to the different plants that cause a dermatitis and to the various plant pollens that cause hay fever, An attempt is made to provide some general information on the extent and severity of poisonings, dermatitis or hay fever caused by  the ingestion or any other contact with various plant parts. More detailed information should be sought from local poison control centers, hospitals, educational institutions, and federal, state and provincial agencies.

     Plant families, genera within each family, and species under each genus are listed alphabetically  using the most widely accepted scientific names. Easy access to the scientific family containing information on any plant can be obtained by referring to the common name of the plant, listed alphabetically, in the following Links to families.

Refer to this web page for Information on plants, of Canada and the northern United States, that are reported to have poisoned livestock, or to have tainted animal products.
Refer to this web page for Additional information on hay fever plants

Links to families

aloes- Liliaceae
- Araceae
autumn crocus- Liliaceae
azaleas- Ericaceae
black cherry- Rosaceae
black locust- Leguminosae
blue cohosh- Berberidaceae
blueweed- Boraginaceae
bracken- Pteridaceae
buckthorns- Rhamnaceae
bulbous buttercup- Ranunulaceae
burningbush- Celastraceae
caladium- Araceae
camases- Liliaceae
candelabra-cactus- Euphorbiaceae
cardinalflowers- Campanulaceae
castor-bean- Euphorbiaceae
chrysanthemums- Compositae
croton- Euphorbiaceae
crown-of-thorns- Euphorbiaceae
daffodil- Amaryllidaceae
daphnes- Thymelaeaceae
dogbanes- Apocynaceae
dumbcanes- Araceae
elders- Caprifoliaceae
English ivy- Araliaceae
false hellebore- Liliaceae
false indigo- Leguminosae
false ragweed- Compositae
foxglove- Scrophulariaceae
gas plant- Rutaceae
giant hogweed- Umbelliferae
glory lily- Liliaceae
golden-bean- Leguminosae
golden-chain- Leguminosae
golden-trumpet- Apocynaceae
greater celandine- Papaveraceae
ground-cherry- Solanaceae
grasses- Gramineae (Poaceae)
grass pea- Leguminosae
Guelder-rose- Caprifoliaceae
heliotrope- Boraginaceae
holly- Aquifoliaceae
honeysuckles- Caprifoliaceae
horse-chestnut- Hippocastanaceae
hydrangea- Saxifragaceae
Indian-tobacco- Campanulaceae
indigos- Leguminosae
Jack-in-the-pulpit- Araceae
Jerusalem-cherry- Solanaceae
jimsonweed- Solanaceae
Kaffir lilies- Amaryllidaceae
Kentucky coffeetree- Leguminosae
lady’s-slippers- Orchidaceae
lamb’s-quarters- Chenopodiaceae
leatherwood- Thymelaeaceae
lily-of-the-valley- Liliaceae
lupines- Leguminosae
maidenhair tree- Ginkgoaceae
May-apple- Berberidaceae
mistletoe- Loranthaceae
monk’s hood- Ranunculaceae
moonseed- Menispermaceae
motherwort- Labiatae
narcissus- Amaryllidaceae
nettles- Urticaceae
night-blooming jessamine- Solanaceae
nightshades- Solanaceae
oleander- Apocynaceae
osage-orange- Moraceae
ox-eye daisy- Compositae
pawpaw- Annonaceae
penciltree- Euphobiaceae
philodendrons- Araceae
poison-hemlock- Umbelliferae
poison-ivys- Anacardiaceae
poison-oak- Anacardiaceae
poison sumac- Anacardiaceae
pokeweed- Phytolaccaceae
poppys- Papaveraceae
potato- Solanaceae
povertyweed- Compositae
precatory-pea- Leguminosae
primula- Primulaceae
privet- Oleaceae
ragweeds- Compositae
red chokecherry- Rosaceae
rhododendrons- Ericaceae
rhubarb- Polygonaceae
skunk-cabbage- Araceae
snowberry- Caprifoliaceae
snowdrop- Amaryllidaceae
spindletree- Celastraceae
spurge-laurel- Thymelaeaceae
spurges- Euphorbiaceae
star-of-Bethlehem- Liliaceae
sweet pea- Leguminosae
Swiss-cheese plant- Araceae
tansy ragwort- Compositae
tobacco- Solanaceae
tree-of-heaven- Simaroubaceae
tulips- Liliaceae
Virginia creeper- Vitaceae
water-hemlocks- Umbelliferae
white snakeroot- Compositae
wild calla- Araceae
wild ginger- Aristolochiaceae
wild parsnip- Umbelliferae
wisterias- Leguminosae
yarrows- Compositae
yews- Taxaceae



Information about plants causing poisoning, a dermatitis, or hay fever

Amaryllidaceae (amaryllis family)

Amaryllis belladonna L. and Amaryllis vittata Ait.- amaryllis
Ornamental herbs, usually grown indoors in our area.
Rare poisonings after the ingestion of bulbs.

Clivia species- Kaffir lilies
House plants.
Small concentrations of certain alkaloids in the plants have caused, very rarely, a mild poisoning.

Galanthus nivalis L.- snowdrop
Outdoor ornamental.
Rare poisonings caused by small concentrations of toxic alkaloids.

Narcissus poeticus L.- narcissus, and Narcissus pseudonarcissus L.- daffodil
Indoor and outdoor ornamentals.
Ingestion of bulbs has caused several hours of severe discomfort. Some people develop a skin dermatitis after handling large quantities of bulbs.

Anacardiaceae (cashew family)

The roots, stems, leaves and fruits of the following Toxicodendron species contain an oil that produces an irritating dermatitis in humans after an initial sensitization. Sensitivity to the poisonous oil varies greatly from person to person, and even during different periods in the same persons lifetime. Humans are not born sensitive to the oil, and therefore are not affected with the dermatitis on first contact with the plants. However, most people can be sensitized after a single contact. In general, children are more sensitive than adults, and people with a light skin react more than those with a pigmented skin. Since the poisonous oil must contact the cells beneath the skin layer, the dermatitis is most common and most severe in areas with thin skin. All of the following Toxicodendron species have clusters of yellow flowers and, later, whitish berries. Colored illustrations of all poisonous Toxicodendron taxa here.

Toxicodendron diversiloba (Torr. & Gray) Greene (=Rhus diversiloba Torr. & Gray- western poison-oak
Usually a trailing vine, confined to the extreme west coast of the United States and southern coast of British Columbia. Native to North America.

Toxicodendron  radicans (L.) Kuntze subsp. negundo (Greene) Gillis [=Rhus radicans L. var. negundo (Gillis) G. A. Mulligan- central poison-ivy
Usually a climbing vine; most common in in the north-central United States and extreme southern Canada.

Toxicodendron radicans subsp. radicans (=Rhus radicans var. radicans)- eastern poison-ivy
Usually a climbing vine; most common in the eastern United States and southeastern Canada. Native to North America.

Toxicodendron radicans subsp. rydbergii (Small ex Rydb.) Á& D.Löve [=Rhus radicans var. rydbergii (Small ex Rydb.) Rehd.]- rydberg’s poison-ivy
A trailing vine; most common in the northern United States and southern Canada.

Toxicodendron vernix (L.) Kuntze (=Rhus vernix L.)- poison sumac
Tall shrub to 20 feet (6m.) high; occasional in swamps and wet locations in the eastern United States, southern Ontario and southwestern Quebec.


Annonaceae (custard-apple family)

Asimina triloba (L.) Dunal- pawpaw
Native tree in the northeastern United States and southwestern Ontario.
Contact dermatitis and severe gastrointestinal symptoms have occurred after the ingestion of fruits.


Apocynaceae (dogbane family)

Allamanda cathartica L.- golden-trumpet
Indoor ornamental climber.
Weak evidence exists that the fruit is poisonous.

Apocynum androsaemifolium L.- spreading dogbane, and Apocynum  cannabinum L.- hemp dogbane
Native herbs in the northern United States and southern Canada.
Sickness and death has resulted from their use for medicinal purposes.

Nerium oleander L.- oleander
Ornamental shrubs.
There are many reports of poisonings and even deaths. Cases of dermatitis have been reported.


Aquifoliaceae (holly family)

Ilex opaca Ait.- American holly
The only reported case of poisoning is of a mild one, after two young children ate “a handful” of berries.


Araceae (arum family)

The leaves, stems, and roots of the following members of the arum family contain needle-shaped calcium oxalate raphide crystals. When eaten, these cause an intense burning sensation in the mouth and throat and the temporary paralysis of the throat muscles. This has resulted in the use of the common name dumbcane for the various species of Dieffenbachia.

Anthurium species- anthuriums
House plants with us.

Arisaema triphyllum (L.) Torr.- Jack-in-the-pulpit
Native herb of eastern North America

Caladium bicolor (Ait.) Vent.- caladium
House plant with us.

Calla palustris L.- wild calla
Native herb throughout our area.

Dieffenbachia amoena Gentil- giant dumbcane, Dieffenbachia bausei Regel- dumbcane, and Dieffenbachia picta Schott- spotted dumbcane
Indoor ornamentals with us.

Monstera deliciosa Liebm.- Swiss-cheese plant
Indoor ornamental climber.

Philodendron species- philodendrons
House plants with us.
Can also cause a dermatitis on the skin of some people.

Symplocarpus foetidus (L.) Nutt.- skunk- cabbage
A native herb in eastern North America.


Araliaceae (aralia family)

Hedera helix L.- English ivy
Outdoor and indoor ornamental.
Poisoning after the ingestion of leaves and berries has been reported, but none of the reports are recent. Some people develop a severe dermatitis after handling leaves.


Aristolochiaceae (birthwort family)

Asarum canadense L.- wild ginger
Native herb in southeastern Canada and the northeastern United States.
Some individuals develop a dermatitis after handling leaves.


Berberidaceae (barberry family)

Caulophyllum thalictroides (L.) Michaux- blue cohosh
Native herb in southeastern Canada and northeast United States.
The berries and roots are cytotoxic.

Podophyllum peltatum L.- May-apple
Native herb in extreme southeastern Canada and in the northeastern United States.
There is only one report of poisoning, apparently from eating young shoots. Ingestion of fruits can cause  a catharsis.


Boraginaceae (borage family)

Echium vulgare L.-blueweed
Biennial herb, forming a flat rosette in the first year. Stems 1 to 3 feet (3 to 9 dm) high. Flowers bright blue. Widespread in the inland-east and rare elsewhere. Rocky permanent pastures, abandoned fields, meadows, and roadsides. Naturalized from Europe. Colored illustration can be viewed here.
Contact with the bristly hairs on the leaves and stems produces a severe skin inflammation and itching in some people.

Heliotropium curassavicum L.- spatulate-leaved heliotrope
Native herb in the mid-west.
Poisonings have occurred when used in herbal teas.


Campanulaceae (bellflower family)

Lobelia cardinalis L.- cardinalflower, Lobelia inflata L.- Indian-tobacco, and Lobellia siphilitica L.- blue cardinalflower
Native herbs.
Sickness and death has resulted when these plants were used for medicinal purposes in pioneer days.


Caprifoliaceae (honeysuckle family)

Mild symptoms of feeling unwell and vomiting  have resulted from eating berries or other plant parts of the following members of the honeysuckle family. Berries can be toxic if large quantities are eaten.

Lonicera species- honeysuckles
Native, naturalized, and ornamental shrubs.

Sambucus species- elders
Native, naturalized, and ornamental shrubs.

Symphoricarpus albus (L.) Blake- thin-leaved snowberry
Native shrub found throughout most of our area.

Viburnum opulus L.- Guelder-rose
Outdoor ornamental shrub or small tree; sometimes naturalized.


Celastraceae (stafftree family)

Euonymus atropurpurea Jacq.- burningbush, and Euonymus europaeus L.- European spindletree
Outdoor ornamental shrubs.
Mild symptoms have been reported to have occurred after eating berries.


Chenopodiaceae (goosefoot family)

Chenopodium album L.- lamb’s-quarters
Annual with stems 1 to 6 feet (3 to 18 dm) high, with inconspicuous green flowers. Widespread in cultivated land, grain fields, gardens, roadsides, and waste places. Naturalized from Europe.
Poisonings occurred in Europe when large quantities were consumed because of a serious food shortage in wartime.


Compositae [Asteraceae] (composite family)

Achillea species- yarrows
Native, naturalized, and ornamental perennial herbs.
An allergic reaction, mainly affecting the eye area, can result from handling  yarrows over a long period of time. Dairy products produced from cows grazing on common yarrow (Achillea lanulosa Nutt.) can have an undesirable  flavor, but are not reported to be poisonous. Colored illustration of common yarrow can be viewed here.

Ambrosia artemisiifolia L.- common ragweed
Annual, stems usually 2 to 3 feet (6 to 9 dm) high; flowers inconspicuous, wind pollinated. Throughout most of our area, but most common in southern Quebec and Ontario and in the eastern United States. In cultivated fields, gardens, vacant lots, and especially along the fringes of roadsides. Native to North America.
Its wind-blown pollen is the most important cause of hay fever in eastern North America. However, there are many other plants with inconspicuous flowers and wind disseminated pollen that are potential causes of hay fever. As a general rule, plants with showy flowers produce small amounts of sticky pollen that adhere to insects and other flower visitors and is transferred by them to the stigmas of  other plants, usually of the same species.  Plants with inconspicuous flowers, usually have light pollen that is blown indiscriminately by the wind. This “wasteful” pollination strategy  requires that the anthers on these plants produce large amounts of  pollen. It is the plants with inconspicuos flowers, not those with showy flowers that cause most hay fever in humans.
Dairy products from cows that have grazed common ragweed often have an objectionable odor and taste, but I have found no reports that they are toxic.

Ambrosia psilostachya DC.- perennial ragweed
Perennial with horizontal rootstocks; a smaller plant with rougher, thicker, and less lobed leaves than common ragweed, but otherwise similar; flowers inconspicuous, wind-pollinated; most common in the mid-west and west, but has recently spread eastward along railway beds; native to North America.
Its wind-blown pollen causes hay fever.

Ambrosia trifida L.- giant ragweed
Annual, from 1 to 10 feet (3 to 30 dm) high; flowers inconspicuous, wind-pollinated. Most common in southwestern Quebec, southern Ontario, southern Manitoba and southward in the United States; roadsides, railway beds, agricultural fields, and waste places. Native to North America.
It is far less abundant than common ragweed, and its air-born pollen is less important as a cause of hay fever.

Artemisia absinthium L.- absinth
Perennial with stems to 5 feet (15 dm) high; flowers inconspicuous; plant strongly aromatic. Throughout our range, but particularly abundant in the mid-west; roadsides, waste places, farmyards, pastures, and cropland. Introduced from Europe.
Absinth is used in the preparation of some alcoholic beverages and was formerly used for medicinal purposes. Its volatile oils are toxic if consumed in large amounts.

Chrysanthemum species- chrysanthemums
Indoor and outdoor ornamentals.
An allergic dermatitis, affecting mainly the eye area, is an occupational hazard for some people who handle chrysanthemums over a long period of time. Similar allergic reactions can develop after prolonged contact with other members of the composite family. Sensitivity developed after prolonged contact with one species often results in an increased sensitivity to other members of the composite family.

Eupatorium rugosum Houtt.- white snakeroot
Native herb of the eastern part of our area.
There are some early reports of sickness and death after drinking milk from cows that have eaten white snakeroot. However, there are no recent reports of any toxicity.

Iva axillaris Pursh- povertyweed
A persistent perennial with underground rootstocks; stems 6 to 8 inches (15 to 20 cm) high; flowers inconspicuous, wind-pollinated; common in the prairie region, less common in dry areas further west; native of  North America.
Where abundant, its wind-blown pollen is an important cause of hay fever.

Iva xanthifolia Nutt.- false ragweed
Annual; stems 3 to 8 feet (9 to 24 dm) high; flowers inconspicuous, wind-pollinated. Common in the mid-west, rare to the east and west; cultivated land, waste land, and gardens. Native to North America.
The abundant wind-blown pollen is an important cause of hay fever. Contact with leaves produces a dermatitis in some people. Milk from cows grazing this plant can have an undesirable flavor, but I have found no reports that it is toxic.

Leucanthemum vulgare Lam.- ox-eye daisy
Perennial with stems 1 to 3 feet (3 to 9 dm) high; ray flowers white; disk flowers yellow. Throughout our area but rare in prairie regions; meadows, pastures, waste places, hayfields, and roadsides. Introduced from Europe.
Milk can have a disagreeable taste after this plant is eaten by cows. I have seen no indication that it is toxic.

Senecio jacobaea L.-tansy ragwort
Biennial or short-lived perennial with stems 1 to 3 feet (3 to 9 dm) high;  flowers yellow; most common in eastern and western maritime areas, rare elsewhere. Pastures, hayfields, roadsides, and waste places. Introduced from Europe.
Poisoning has resulted from its use in herbal teas.


Ericaceae (heath family)

Rhododendron species- azaleas and rhododendrons
Native and ornamental shrubs.
Serious intoxications have occurred after children have eaten either leaves or flowers.


Euphorbiaceaa (spurge family)

Codiaeum variegatum (L.) Blume- croton
Ornamental shrub or small tree.
Ingestion of bark or roots has caused an irritation in the oral cavity and contact with the latex has produced  an eczema.

The latex of all of the following  species of the genus Euphorbia causes a dermatitis on the skin of most people and can cause sickness or death if ingested.

Euphorbia cyparissias L.-cypress spurge
Perennial, with underground rootstocks;  stems up to 1 foot (3 dm) high; flowering inflorescences yellow; locally common throughout most of our range, especially in the inland-east; roadsides, waste places, pastures, and open woods; often an escape from older cemeteries. Introduced from Europe as an ornamental.

Euphorbia esula L.- leafy spurge
Perennial, spreading mainly by its persistent, vertical and horizontal underground  roots. Stems erect, from 1 to 3 feet (3 to 9 dm.) high. Flowering inflorescences from green to yellow. Locally common throughout most of our area, particularly  the mid-west; grain fields, meadows, pastures, prairie, rangeland, roadsides, and waste places. Introduced from Europe and Asia.

Euphorbia helioscopia L.- sun spurge
Sporadically naturalized throughout our area.

Euphorbia lactea Haw.- candelabra-cactus
Ornamental shrub.

Euphorbia lathyris L.- caper spurge
Ornamental herb; sparingly naturalized in the coastal-west.

Euphorbia milii Ch. des Moulins- crown-of-thorns

Euphorbia peplus L.- petty spurge
Sparingly naturalized throughout our area.

Euphorbia tirucalli L.- penciltree
Ornamental tree.

Ricinus communis L.- castor-bean
Ornamental tree.
Ingestion of only a few beans can cause poisoning or even death.


Ginkgoaceae (ginkgo family)

Ginkgo biloba L.- maidenhair tree
Ornamental tree.
Severe dermatitis has resulted from handling broken or crushed fruits.


Gramineae (grass  family)

Most members of the grass family have inconspicuous flowers that produce large amounts of wind-blown pollen that can cause hay fever in sensitive individuals.


Hippocastanaceae (horse-chestnut family)

Aesculus hippocastanum L.- horse-chestnut
Ornamental tree.
Rare reports of children being poisoned after the ingestion of nuts.


Labiatae (mint family)

Leonurus cardiaca L.- motherwort
Sparingly naturalized throughout our area.
Some people have developed a dermatitis after contact with the leaves.


Leguminosae (pea family)

Abrus precatorius L.- precatory-pea
Seeds are used in necklaces and bracelets that are sometimes brought into our area by residents who have purchased them while traveling abroad.
The seeds are very poisonous.  One ingested seed is often enough to be fatal even to a mature adult.

Baptisia tinctoria (L.) Br.- wild indigo and Baptisia leucantha T. & G.- wild false indigo
Perennial herbs, native to southern Ontario and southward into the United States.
Both plants are reported to be toxic.

Gymnocladus dioicus (L.) K. Koch- Kentucky coffeetree
Ornamental tree.
There is an 1898 report of a woman being poisoned as the result of eating the fruit pulp. I could find no other report of poisoning.

Laburnum anagyroides Medic.- golden-chain
Ornamental shrub or tree.
Although it is considered the second most poisonous tree in Britain, I could find no documentation of fatalities.

Lathyrus odoratus L.- sweet pea (an ornamental climber) and Lathyrus sativus L.- grass pea (a food and forage herb)
Both species can cause serious poisoning if used habitually as a food source.

Lupinus species- lupines
Native, naturalized, and ornamental herbs.
Mild poisoning has occurred after the ingestion of seeds.

Robinia pseudoacacia L.- black locust
Ornamental shrub or tree; sporadically naturalized.
Sickness is reported to have occurred after the ingestion of seeds and inner bark.

Thermopsis rhombifolia (Nutt.) Richards- golden-bean
Native  herb in the western half of our area.
Seeds have been implicated in the poisoning of children in Western Canada.

Wisteria species- wisterias
Woody ornamental climbers.
Children are reported to have been poisoned after the ingestion of seeds or pods.


Liliaceae (lily family)

Aloe species- aloes
Perennial  house plants.
The latex present in the leaves can cause poisoning if ingested.

Colchicum autumnale L.- autumn crocus
Indoor and outdoor ornamental.
Ingestion causes a burning sensation in the mouth and throat.

Convallaria majalis L.- lily-of-the-valley
Ornamental herb.
Ingestion of any plant part can cause sickness. The report that a child had died after drinking water in which this plant had been standing has been questioned by some authors.

Gloriosa superba L.- glory lily
Ornamental climber.
Sickness and death has occurred after the ingestion of tubers.

Ornithogalum umbellatum L.- star-of-Bethlehem
Outdoor ornamental.
Nausea and intestinal disorders have occurred in children after eating flowers.

Tulipa species- tulips
Indoor and outdoor ornamental.
Some people develop a severe dermatitis, called tulip finger, after repeatedly handling large quantities of   bulbs.

Veratrum viride Ait.- false hellebore
Native herb of the eastern part of our area and the extreme west.
Very poisonous. Sickness and even death will result from the ingestion of any part of this plant.

Zigadenus elegans Pursh- white camas and Zigadenus gramineus Rydb.- death camas
Native herbs.
Very poisonous. Sickness and even death has occurred after the ingestion of bulbs.


Loranthaceae (mistletoe family)

Phoradendron flavescens (Pursh) Nutt.- American mistletoe
Native south of our area. Sold around Christmas.
Mild poisonings, have been reported, after the ingestion of berries.


Menispermaceae (moonseed family)

Menispermum canadense L.- moonseed
Native in the southern part of our non-maritime east..
Poisoning and death has occurred after eating the grapelike fruits.


Moraceae (mulberry family)

Maclura pomifera (Raf.) C. K. Schneid.- osage-orange
Small ornamental tree.
Some people develop a dermatitis after contacting the milky sap.


Oleaceae (olive family)

Ligustrum vulgare L.- common privet
Ornamental shrub.
There are reports of the  poisoning of children after the ingestion of berries. I have seen no documentation of these reports.


Orchidaceae (orchid family)

Cypripedium species- native lady’s-slippers
Native species.
A dermatitis can result after contacting the glandular hairs on the plants.


Papaveraceae (poppy family)

Chelidonium majus L.- greater celandine
Naturalized herb in the eastern part of our area.
Severe irritation and gastrointestinal problems are reported.

Papaver species- poppys
Ornamental herbs.
Toxic substances, that can cause poisoning if ingested, are present in the foliage and pods of many species.


Phytolaccaceae (pokeweed family)

Phytolacca americana L.- pokeweed
Native herb of the eastern United States and  extreme southeastern Canada.
Has caused severe poisonings when used as a folk medicine.


Polygonaceae (buckwheat family)

Rheum rhaponticum L.- rhubarb
Perennial crop plant.
Sickness and death are reported to have occurred after the ingestion of large quantities of leaves.


Primulaceae (primrose family)

Primula obconica Hance.- primula
Ornamental herb.
A severe skin dermatitis occurs in some people after contact with an irritant in the glandular hairs on the flower stalks and calyx.


Pteridaceae (fern family)

Pteridium aquilinum (L.) Kuhn- bracken
Perennial, with extensive creeping and forking underground rhizomes; fronds 3 to 15 feet (9 to 45 dm) high; throughout, except the mid-west; abandoned fields, open woods, swamps, bogs, burnt-over areas, grassy slopes, roadsides, and waste places. Native to North America.
Although sometimes eaten as a substitute for “fiddleheads”, recent evidence indicates that it can be carcinogenic.


Ranunculaceae (crowfoot family)

Aconitum napellus L.- monk’s hood
Outdoor ornamental herb.
Very poisonous if ingested, especially the root.

Ranunculus bulbosus L.- bulbous buttercup
Sparingly naturalized in the eastern part of our area.
Children have been poisoned from the ingestion of bulbous plant parts.


Rhamnaceae (buckthorn family)

Rhamnus cathartica L.-European buckthorn and Rhamnus frangula L.- alder buckthorn
Naturalized shrubs or small trees, introduced from Europe.
Rare cases of  mild poisonings have occurred after eating fruits. The plants contain substances with laxative properties.


Rosaceae (rose family)

Prunus serotina Ehrh.- black cherry and Prunus virginiana L.- red chokecherry
Native shrubs  and small trees.
Poisoning and even the death of children has occurred as the result of them eating large quantities of fruits without removing the seeds.


Rutaceae (rue family)

Dictamnus albus L.- gas plant
Ornamental herb.
Photosensitization can occur as the result of handling the plant, especially the seed pods; reddish patches can persist on the skin for weeks.


Saxifragaceae (saxifrage family)

Hydrangea macrophylla (Thunb.) Ser.- hydrangea
Woody ornamental.
Illness has occurred after the ingestion of leaves or roots. Repeated handling of this plant by a nursery man resulted in a dermatitis on his hands.


Scrophulariaceae (figwort family)

Digitalis purpurea L.- foxglove
Cultivated herb; sporadically naturalized.
Children have become sick after eating flowers, seeds, or leaves.


Simaroubaceae (quassia family)

Ailanthus altissima (Mill.) Swingle- tree-of-heaven
Ornamental tree.
A skin dermatitis can occur as the result of contact with the leaves.


Solanaceae (nightshade family)

Cestrum nocturnum L.- night-blooming jessamine
Ornamental shrub.
Sickness has occurred after eating this plant.

Datura stramonium L.- jimsonweed
Naturalized herb.
Sickness and death have occurred as the result of eating plant parts.

Nicotiana tabacum L.- tobacco
Cultivated herb.
Fresh leaves are toxic if eaten.

Physalis peruviana L.- ground-cherry
Ornamental herb.
Fruits are reported to be mildly toxic.

Solanum dulcamara L.- climbing nightshade
Woody climber; flowers purple; throughout, except mid-west; hedges, wood openings, and waste places. Introduced from Europe.
Berries are mildly poisonous, but serious illness has occurred after large quantities were eaten.

Solanum nigrum L.- black nightshade
Naturalized herb scattered throughout most of our area.
Although sometimes eaten as a food, the fruit (especially unripe ones) can cause a serious illness.

Solanum pseudo-capsicum L.- Jerusalem-cherry
Small ornamental shrub.
Nausea, abdominal pains, dilation of the pupils, and drowsiness, after eating its fruits has been  reported.

Solanum tuberosum- potato
Common vegetable.
Sickness and even death has occurred after eating large quantities of green-skinned potatoes or green fruits.


Taxaceae (yew family)

Taxus species- yews
Native and ornamental shrubs; widely distributed.
Needles and seeds, but apparently not the flesh part of the berries, are toxic if ingested. Poisonings are rare.


Thymelaeaceae (mezereum family)

Daphne species- daphnes and spurge-laurel
Ornamental shrubs.
Poisonings are usually mild as few berries are eaten because of their acrid taste.

Dirca palustris L.- leatherwood
Shrub, native in eastern part of our area.
Some people develop a severe irritation and blistering of the skin after handling the bark of this plant.


Umbelliferae (parsley family)

The following water-hemlocks (Cicuta species) are extremely poisonous . Numerous sicknesses and deaths have been recorded. The most frequent poisonings have occurred after the ingestion of rootstocks.

Cicuta  douglasii (DC.) Coult. & Rose- western water-hemlock
Native herb in the western part of our area.

Cicuta maculata L.- spotted water-hemlock
Perennial with flowering stems 3 to 6 feet (9 to 18 dm) high; flowers white. Throughout our area. The most widespread of the three poisonous water-hemlocks. In wet habitats, especially along the margins of rivers, streams, and lakes. Native to North America.

Cicuta virosa L.- northern water-hemlock
Native in moist habitats in northern Canada and Alaska.

Conium maculatum L.- poison-hemlock.
Biennial, with a disagreeable odor. Stems up to 6 feet (18 dm) high; flowers white. A very rare plant in our area. It occasionally grows in field borders, roadsides, and waste places. Introduced from Europe. Very poisonous. Sickness and death has occurred after the ingestion of  leaves, roots or seeds.

Heracleum mantegazzianum Somm. & Lev.- giant hogweed
Naturalized herb in southern Ontario and the adjacent United States.
A rash and persistent skin blisters can result when the handling of leaves is followed by an exposure to sunlight.

Pastinaca sativa L.- wild parsnip
Biennial, with stems up to 3 feet (9 dm) high; flowers yellow; throughout, especially common in moist habitats in the non-maritime east; pastures, hayfields, ditches, riverbanks, roadsides, and waste places. Introduced from Europe.
Some people develop a severe dermatitis after having made contact with leaves, stems, or seeds.


Urticaceae (nettle family)

Laportea canadensis (L.) Gaud.- Canada nettle
Native herb in the eastern half of our area.
A toxic liquid in in the stem hairs causes an intense itching and pain.

Urtica dioica L.- stinging nettle
Perennial, with stems 1 to 8 feet (3 to 24 dm) high; flowers inconspicuous. Throughout our area; roadsides, waste places, and along margins of streams, rivers, and lakes. Both native populations and European introductions occur.
Contact with a toxic liquid in its sharp hairs will cause intense itching and pain.


Vitaceae (grape family)

Parthenocissus quinquefolia (L.) Planch.- Virginia creeper
Native climbing vine occurring in the eastern half of our area.
Ingestion of large quantities of berries can cause severe poisoning. The leaves contain raphides that will cause an irritation of the skin of some people.

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