Tip: Toxic Plants

Common Name/ Scientific Name	Plant Type	Part of Plant	Degree of toxicity	Poisonous Compound	Cumulative?	Livestock effects**
Arrowgrass (Triglochin maritima)		All	Can be severe	Glycosides (produce cyanide)		Under some conditions can cause illness & death in livestock.
Baneberry (Actaea rubra)	Forb	All, esp. roots & berries	Moderate – Severe	Protoamemonin and probably a glycoside or essential oil		Stomach cramps, dizziness, vomiting, circulatory failure, headache. European species have caused death.
Bleeding-heart (Dicentra spp.)	Forb	All	Mild – Moderate	Alkaloids		Trembling, agitation, heavy salivation, vomiting, diarrhea, convulsions, difficult breathing.
Boxwood (Buxus sempervirens)	Shrub	All	Moderate – Severe	Steroidal alkaloids (buxine)		Abdominal pains, vomiting, diarrhea. Large doses can cause convulsions, coma & death.
Bracken Fern (Pteridium aquilinum)	Fern	All	Mild – Severe	Thiaminase enzyme, carcinogens , often glycosides (prunasin)	Yes	Thiamine deficiency, which can be fatal. Cumulative effects may include cancer. Poisonous compounds can pass into milk.
Buttercups (Ranunculus spp.)	Forb	All	Mild – Moderate	Protoanemonin from ranunculin glycoside		Inflammation and blistering of skin, gastrointestinal irritation. Usually only present in fresh plants, not dried.
Camas, Death (Zigadenus venenosus)	Forb	All	Severe	Steroidal glycosidal alkaloid		Salivation, weakness, respiratory difficulty, nausea, convulsions, coma, death.
Cherry, Choke (Prunus virginiana)	Tree	Seeds, leaves, bark	Moderate – Severe	Cyanogenic glycoside (produces cyanide)		Initial rapid breathing followed by slow, difficult breathing, anxiety, excitement, confusion, headache, vomiting, dizziness, can cause death. Other related species which may be poisonous include mountain ash (Sorbus spp.), Hawthornes (Crataegus spp.), Pyracantha, Cotoneaster
Clematis (Clematis spp.)	Vine	All	Mild – Moderate	Protoanemonin from ranunculin glycoside		Inflammation and blistering of skin, gastrointestinal irritation. Usually only present in fresh plants, not dried.
Cocklebur (Xanthium strumarium)	Forb	All, esp. seeds & seedlings	Moderate – Severe	Glycosides		Loss of appetite, vomiting, weakness, ataxia, spasms, in severe cases death.
Crocus, Autumn (Colchicum autumnal)	Forb	All, esp. bulb and seeds	Moderate – Severe	Alkaloids (colchiceine)		Burning pain in the mouth & throat, nausea, vomiting, diarrhea, lethargy, low blood pressure, shock, convulsions, coma, death (with larger doses).
Cucumber, Wild (Marah oreganus)	Vine	Fruit	Mild – Severe	Saponic glycosides		Chest pains, shortness of breath, can cause death.
Daffodil & Narcissus (Narcissus spp.)	Forb	All, esp. bulbs	Moderate – Severe	Alkaloids (glycoside)		Dizziness, abdominal pain, nausea, vomiting, diarrhea. Large doses can cause trembling, convulsions & death.
Domestic plums, cherries, peaches, apricots, apples, pears, (Prunus spp., Malus spp., Pyrus spp.)		Seeds, leaves, bark	Mild- Moderate	Cyanogenic glycoside (produces cyanide)		Initial rapid breathing followed by slow, difficult breathing, anxiety, excitement, confusion, headache, vomiting, dizziness, can cause death in large quantities. Toxicity may be variable. Other related species which may be poisonous include mountain ash (Sorbus spp.), Hawthornes (Crataegus spp.), Pyracantha, Cotoneaster
Elderberry (Sambucus spp.)	Shrub	Leaves, stems, bark and roots	Mild – Moderate	Alkaloid & cyanogenic glycoside (produced cyanide)		Nausea, vomiting, diarrhea. Raw fruits can cause nausea.
European bittersweet (Solanum dulcamara)	Vine	All, especially green berries	Moderate – Severe	Alkaloidal glycoside (Solanine)		Abdominal pain, headache, flushed skin, tiredness. Severe cases include vomiting, thirst, difficult breathing, paralysis, dilated pupils, diarrhea, can cause death. Green potatoes contain the same chemical but in lower concentrations.
Fiddleneck or Tarweed (Amsinckia sp.)	Forb	All	Moderate	Thiaminase, Pyrrolizidine alkaloids	Yes	Appetite loss, timid, stupified, incoordination, liver lesions, enlarged liver (same as Tansy Ragwort) Foxglove (Digitalis purpurea) Forb All Severe Digitoxin and other glycosides Contracted pupils, nausea, vomiting, cramps, severe headache, irregular heartbeat, labored breathing, convulsions, death, usu. a problem only in hay
Golden Chain (Laburnum anagyroides)	Tree	All, esp. bark & seeds	Moderate – Severe	Alkaloid (systine) – similar effects to nicotine		Nausea, vomiting, abdominal pain, diarrhea, drowsiness, headache, dizziness, fever, irregular heartbeat, dilated pupils. Severe cases can have convulsions, coma & death. The toxicity varies widely.
Groundsel, Common (Senecio vulgaris)	Forb	All	Moderate	Pyrrolizidine alkaloids	Yes	Liver lesions, enlarged liver, abdominal pain, weakness, staggering, death. Liver damage is permanent. Usually only eaten in hay or when wilted. Drying or storage doesn’t destroy toxins.
Hellebore, False (Veratrum spp.)	Forb	All, esp. the rhizome	Moderate – Severe	lkaloids		Abdominal pain, vomiting diarrhea, paralysis, spasms. In severe cases can cause death. Can cause birth defects if eaten during certain gestation periods.
Hemlock, Poison (Conium maculatum)	Forb	All	Severe	Coniine and other alkaloids		Teeth grinding, muscle spasms, respiratory failure, death.
Hemlock, Water (Cicuta spp.)	Forb	All	Severe	Cicutoxin		Nausea, salivation, vomiting, convulsions, fever, low hear rate, abdominal pain, dilated pupils, delirium, coma, respiratory paralysis, death. Water Parsley (Oenanthe spp.) may contain similar toxin.
Holly, English (Ilex aquifolium)	Shrub	Berries, leaves	Mild	Glycosides and alkaloids		Nausea, vomiting, diarrhea, drowsiness.
Horse Chestnut (Aesculus hippocastanum)	Tree	All	Moderate - Severe	Saponin glycoside, alkaloids		Inflammation of mucous membranes, vomiting, thirst, weakness, muscular twitching, dilated pupils, stupor, paralysis. Coma & death can occur in severe cases.
Horsetail (Eqisetum arvense)	Fern-ally	All	Mild - Moderate	Thiaminase	Yes	Destroys vitamin B1 – Symptoms include weight loss, weakness, eventual death.
Iris or Yellow Flag (Iris pseudacorus)	Forb	All, esp. rhizomes	Moderate – Severe	Glycoside		Abdominal pain, nausea, vomiting, diarrhea, fever, large doses can cause death.
Ivy, English (Hedera helix)	Vine	All, esp. leaves & berries	Moderate	Triterpene saponins (glycosides)		Large quantities cause vomiting, diarrhea, spasms, staggering, paralysis.
Knapweed, Russian and Yellowstar Thistle (Centaurea spp.)	Forb	All	Moderate		Yes	Brain deterioration resulting in “Chewing disease”, can eventually cause death by starvation.
Knotweeds (Polygonum spp.)	Forb	All	Mild	Oxalic acid		Large quantities can cause interference with calcium metabolism in the body & possible phototoxicity.
Lambsquarters (Chenopodium album)	Forb	All	Mild	Oxalates		Large quantities can cause interference with calcium metabolism in the body & possible phototoxicity.
Larkspur (Delphinium spp.)	Forb	All	Severe	Alkaloids (delphinine)		Constipation, bloat, dilation of pupils, vomiting, depression, paralysis, death.
Laurel, English (Prunus laurocerasus)	Shrub	Seeds, leaves, bark	Mild - Moderate	Cyanogenic glycoside (produces cyanide)		Initial rapid breathing followed by slow, difficult breathing, anxiety, excitement, confusion, headache, vomiting, dizziness, can cause death in large quantities. Toxicity may be variable. Other related species which may be poisonous include mountain ash (Sorbus spp.), Hawthornes (Crataegus spp.), Pyracantha, Cotoneaster.
Lily of the Valley (Convallaria majalis)	Forb	All	Severe	Cardiac glycosides (digitalis-like)		Burning pain in mouth & throat, salivation, nausea, vomiting, abdominal pain, headache, dilated pupils, slow & irregular heartbeat, sometimes coma and death.
Locust, Black or Honey (Robinia pseudo-acacia)	Tree	All	Mild - Moderate	Poisonous proteins		Lassitude, nausea, vomiting, abdominal pain, diarrhea, delirium, coma, death in livestock in severe cases.
Lupine (Lupinus spp.)	Forb	All	Moderate	Alkaloids (lupinine)	Yes	Birth defects, spasms, vomiting, nausea, dizziness, headache, abdominal pain, & in severe cases death.
Nightshade, Black (Solanum nigrum) Nightshade, Hairy (Solanum sarrachoides)	Vine	All, especially green berries	Moderate – Severe	Alkaloidal glycoside (Solanine)		Abdominal pain, headache, flushed skin, tiredness. Severe cases include vomiting, thirst, difficult breathing, paralysis, dilated pupils, diarrhea, can cause death. Green potatoes contain the same chemical but in lower concentrations.
Oak (Quercus spp.)	Tree	All, but esp. acorns	Slight	Tannins (?)		Constipation, blood in urine.
Pea, Wild; Sweet Pea (Lathyrus spp.)	Forb	Foliage, seeds	Mild	Toxic amino acids		Paralysis, convulsions, death. Toxic only in large quantities.
Pigweed (Amaranthus spp.)	Forb	All	Mild	Oxalates, nitrates		Large doses can cause fluid accumulation around kidneys.
Poison Oak, Poison Ivy (Toxicodendron spp.)	Shrub/ Vine	All	Mild - Moderate	Oleoresin (urushiol)	Yes	Itching, burning, redness of skin, blisters
Ponderosa Pine (Pinus ponderosa)	Tree	Needles	Mild - Moderate			Abortion
Ragwort, Tansy (Senecio jacobea)	Forb	All	Moderate	Pyrrolizidine alkaloids	Yes	Liver lesions, enlarged liver, digestive disturbances, restlessness, lack of coordination, weakness, staggering, death. Liver damage is permanent. Usually only eaten in hay or when wilted. Drying or storage doesn’t destroy toxins. Toxins can contaminate milk & honey.
Rhododendron (Rhododendron spp.)	Shrub	All	Mild – Severe	Glycosides		Burning of lips, mouth, salivation, nausea, severe vomiting, coma & death in the most severe cases. The toxin can contaminate honey.
Rhubarb (Rheum rhabarbarum)	Forb	Leaves	Moderate	Oxalic acid & oxalates (irritant poison)		Abdominal pain, nausea, vomiting, difficulty breathing, drowsiness, large doses can cause convulsions, coma & death. Oxalic acid interferes with calcium metabolism as well.
Scotch Broom (Cytisus scoparius)	Shrub	All	Mild - Moderate	Quinolizidine alkaloids		Nausea, vomiting, dizziness, headache, abdominal pain.
Serviceberry (Amalanchier alnifolia)	Shrub	Leaves, twigs	Mild - Moderate	Cyanogenic glycoside (produces cyanide)		Initial rapid breathing followed by slow, difficult breathing, anxiety, excitement, confusion, headache, vomiting, dizziness.
Skunk Cabbage (Lysichitum americanum)	Forb	All	Mild – Moderate	Calcium oxalate crystals		Physical irritation and swelling of mouth, throat, etc. as crystals pierce the skin.
Snowberry (Symphoricarpos albus)	Shrub	Berries	Moderate - Severe	Alkaloids		Severe Vomiting, dizziness, semi-comatose state.
Sorrel (Rumex spp.)	Forb	All	Mild	Oxalic acid		Large quantities can cause interference with calcium metabolism in the body.
St. John’s-Wort or Goatweed, Klamath Weed (Hypericum perforatum)	Forb	All	Mild - Moderate	Hypericin		Photosensitization – blisters, swelling and lesions on the skin, particularly light-skinned animals. Subsequent exposure has more severe symptoms. Loss of appetite, diarrhea, increased respiration & heartbeat, high temp., blindness, convulsions, sometimes coma & death. Symptoms are often delayed.
Swamp laurel (Kalmia sp.)	Shrub	Leaves, flowers	Mild – Moderate	Andromedo-toxin, arbutin		Burning of lips, mouth, salivation, nausea, severe vomiting, coma & death in the most severe cases.
Tansy, Common (Tanacetum vulgare)	Forb	All	Moderate - Severe	Tanacetin		Rapid pulse, stomach inflammation, convulsions, abortion, occasionally fatal. However, rarely grazed because of strong taste and smell.
Tarweed (Amsinckia spp.)	Forb	All	Moderate	Pyrrolizidine alkaloids	Yes	Liver lesions, enlarged liver, digestive disturbances, restlessness, lack of coordination, weakness, staggering, death. Liver damage is permanent. Usually only eaten in hay or when wilted. Drying or storage doesn’t destroy toxins.
Vetch, Common (Vicia sativa)	Forb	Foliage, seeds	Mild - Severe	Cyanogenic glycosides (produces cyanide)		Amount of toxins in plants highly variable. Initial rapid breathing followed by slow, difficult breathing, anxiety, excitement, confusion, headache, vomiting, dizziness, can cause death.
Yarrow (Achillea millefolium)	Forb	All	Mild	Glucosides & alkaloid		If eaten in quantity can cause gastric problems.
Yew (Taxus brevifolia)	Tree	All, except perhaps the flesh around the seed.	Moderate – Severe	Alkaloid (taxine), ephedrine, cyanogenic glycoside		Gastroenteritis, nausea, vomiting, diarrheas, rash, drowsiness, irregular heartbeat, labored breathing, trembling, collapse. Large amounts can cause death.

* Most poisonous plants are not readily consumed because they taste bad or feel bad in the mouth. Most species included in this list are not commonly grazed but may be consumed in hay, as shrub trimmings which are left accessible, as bulbs exposed through soil-turning activities, or if there is little other feed in the pasture or confinement area.

** Many of these plants have similar effects on humans! The major symptoms and effects are listed, but the list is NOT all-inclusive. Consult the local Poison Control Center for a complete listing and information about treatment.

SOURCES:
Plants that Poison Livestock in Thurston County, by Thurston County Noxious Weed Control Agency
Pasture Management for Horses and Ponies, by Gillian McCarthy
Common Poisonous Plants and Mushrooms of North America, by Nancy J. Turner and Adam F. Szczawinski
A Guide to Selected Weeds of Oregon (Supplement), by Hawkes, et.al., Oregon Department of Agriculture 1989

Compiled by: Marty Chaney, Pasture Management Specialist
USDA – Natural Resources Conservation Service, Olympia, WA 12/99

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