WSU Extension > Kittitas County > Agriculture Overview > Natural Resources > Forestry and Range > Toxic Plants of Kittitas County

Toxic Plants of Kittitas County

Prepared by Tipton D. Hudson. Originally published September 2005, updated February 2009 (PDF).


Family	Genus	Species	Common Name	Toxicity Rating	Toxic plant part(s)	Symptoms of poisoning	Toxic principle	Affected livestock	Distribution in Kittitas County
Borage	Amsinckia	intermedia	Fiddleneck	High -- 20 lbs. single dose or cumulative	All, especially the seeds	Hepatic cirrhosis, dematitus, aimless wandering, head pressing	Pyrrolizidine alkaloids	all, esp. in hay or contaminated grain	Common
Borage	Cynoglossum	officinale	Houndstongue	High -- 0.6 - 2% of hay, 1 plant per day for a week, or cumulative	all, generally not palatable except in hay	Dullness, wandering, increased pulse and respiration, weakness, death from liver hemorrhage	Pyrrolizidine alkaloids	cattle, horses, sheep less so	Common
Buckwheat	Rumex	crispus	Curly Dock	Low -- large quantities	Top, leaves, stem	muscle tremors, tetany, weakness, reluctance to move, coma, death	Soluble oxalates	Sheep, Cattle, and horses	Common
Buttercup	Aconitum	spp.	Monkshood	High -- Small quantities	all	Labored breathing, irregular heart beat, weakness, muscle spasms, death	Diterpene alkaloids	all	Rare
Buttercup	Delphinium	spp.	Larkspur	Very High -- 1 lb. Cattle appear to be attracted to it	all, fresh or dry	Constipation, bloat; death from respiratory and cardiac failure. Livestock deaths are common	Diterpene alkaloids	all, esp cattle	Occasional
Buttercup	Ranunculus	spp.	Buttercups	Low -- large quantities, may develop a taste for plant	All	Mouth blisters, salivation, diarrhea	Glycoside (ranunculin)	all	Common
Dogbane	Apocynum	spp.	Dogbane	High -- 0.5 - 1 oz./100 lbs body weight	All, especially leaves and stems	Dilation of pupils, sore mouth, sweating, death	Cardiac glycosides	horses, cattle, sheep goats	Occasional
Fern	Pteridium	aquilinum	Bracken Fern	Low -- cumulative, 20% of diet	all, fresh or dry	Loss of weight, depression, body weakness, convulsions	Thiaminase, tannins, cyanogenic glycosides	Cattle, horses, sheep	Occasional--upper county
Figwort	Digitalis	purpurea	Foxglove	Very High -- 0.25 lb.	all	Contracted pupiles, labored breathing, convulsions, death is likely if ingested	Cardiac glycosides	all	Rare---occasionally in upper county
Frumitory	Dicentra	spp.	Bleeding Heart, Steer's head	Moderate -- generally avoided but may eat in early spring	All	Shaking, staggering, excessive salivation, labored breathing, abdominal pain, convulsions	Alkaloids	Cattle and horses	Occasional; also as ornamentals
Goosefoot	Kochia	scoparia	Kochia	Low -- Prolonged grazing (30 days)---useful forage otherwise	Mainly the seeds, increased when stressed	Photosensitization, aimless walking, blindness, gastrointestinal distress	Nitrates, saponins, oxalates	Cattle, horses, sheep	Common
Grass	Sorghum	spp.	Sudan grass, Johnson grass	Low -- large quantities, cumulative	all; safe forage unless stressed	Posterior ataxia, Mucous membranes appear cherry-red, Open mouth breathing,	Cyanogenic glycosides, nitrates	Cattle, sheep, horses	Occasional
Heath	Ledum	glandulosum	Labrador Tea	High -- small % of body weight	All, esp. leaves	Slow/irregular heart rate, blurred vision, excessive salivation, vomiting, colic, labored breathing, coma, death	Diterpenoid compounds	All	Occasional
Honeysuckle	Sambucus	spp.	Elderberry	Low -- if ingesting young shoots, leaves, or bark. Uncooked berries may cause nausea	All, esp. leaves and bark. Berries safe to eat in small amounts if cooked	Stomach pain, nausea, vomiting, diarrhea, weakness, possible death in severe cases	Cyanogenic glycosides	Cattle, sheep , pigs,	Common
Horsetail	Equisetum	spp.	Horsetail, Scouring rush	Low -- large quantities, cumulative	all	Weight loss, weakness, central nervous system disorders, death	Thiaminase	horses, esp. in hay	Common
Iris	Iris	spp.	Iris	Low -- large quantities	all	gastrointestinal distress	Irritant resin	all	Common
Lily	Veratrum	californicum	False hellebore	Low -- large quantities, but is readily eaten by sheep & goats	All	Burning in mouth and throat, salivation, vomiting, paralysis, reproductive problems (monkey face in lambs)	Steroidal alkaloids	Cattle, sheep, and goats	Common
Lily	Zigadenus	spp.	Death camas	High -- Sheep - 0.5 - 2 lbs. Cattle - 5 - 10 lbs.	All, esp. new growth	Weakness, prostration, convulsions, coma, death	Steroid alkaloids	Cattle, horses, sheep, llamas, goats	Occasional
Milkweed	Asclepias	speciosa	Showy milkweed	High -- .05 - 2% body weight	all, fresh or dry	Staggering, depression, weakness, dilated pupils, coma, death	Cardiac glycosides	all	Common
Mustard	Brassica	spp.	Mustards	Low -- Large; excessive consumption--safe forage otherwise	all, fresh or dry	Not life threatening, causes repeated colic if hay is substantially contaminated; has also been known to cause Congenital Hypothyroid Dysmaturity Syndrome in foals	Mustard oils, goitrogenic glycosides	all	Common
Mustard	Descurainia	pinnata	Tansy mustard	Low -- cumulative, large quantities, prolonged grazing	all	Blindness, inability to use tongue, aimless wandering, weight loss	Unknown	Cattle, horses, pigs	Occasional
Mustard	Thlaspi	arvense	Pennycress	Low -- large quantities, possible in hay or grain	Seeds & leaves, fresh or dry	Gastrointestinal distress, peeling skin, in severe cases paralysis and possible death	Glucosinolates	All	Common
Nightshade	Datura	stramonium	Jimsonweed	Very High -- 0.08% body weight	all, generally unpalatable	Paralysis, delirium, respiratory paralysis & death is likely	Tropane alkaloids	all	Rare
Nightshade	Hyoscyamus	niger	Black Henbane	High -- small quantities	all, fresh or dry	Effects central nervous system with stimulatory and hallucinatory effects	Tropane alkaloids	all	Very Rare
Nightshade	Solanum	ssp.	Nightshade	High -- 1-10 lbs.	all	Diarrhea, incoordination, paralysis, convulsions, death	Steroidal glycoalkaloids	All esp. cattle and pigs	Common
Parsley	Cicuta	douglasii	Water hemlock	Very High -- 0.2 - 0.8 lb	all	Violent central nervous system effects, rapid and violent death is likely	resinoid (cicutoxin)	all	Common
Parsley	Conium	maculatum	Poison hemlock	High -- 1 - 10 lbs.	all	Paralysis, respiratory failure & death, birth defects	Piperidine alkaloids	all	Occasional
Pea	Astragalus	spp.	Milkvetches and locoweeds	Moderate -- 30% bodyweight but acquire a taste for it and seek it out	all	Respiratory distress, paralysis, depression, vacant staring, head pressing, belligerent, reproductive problems	Indolizindine alkaloid	cattle, sheep, esp. horses	Occasional in shrub steppe areas
Pea	Lupinus	spp.	Lupine	High -- Sheep - 0.25 lb Cattle - 1 lb	all	Spasms, cerebral excitement, death, birth defects (crooked calf)	Quinolizidine and piperidine alkaloids	sheep, goats, horses, cattle	Common, wide variation in toxicity among subspecies
Pea	Trifolium	spp.	alsike clover, red clover	Low -- cumulative, prolonged grazing	all	blindness, depression, photosensitization, staggering gait, cirrhosis of the liver and severe kidney problems	Unknown compounds, nitrates	Cattle and horses	Occasional
Pea	Vicia	villosa	Hairy Vetch	Low -- large quantities, cumulative	plant, seeds	Skin irritation, poor appetite, diarrhea, convulsions and death from quantities of seed	unknown in plant, seeds contain cyanide	Horses and cattle	Common
Pigweed	Amaranthus	retroflexus	Redroot Pigweed	Moderate -- significant quantities, cumulative	all	Muscle weakness and tremors, ataxia, knuckling at the fetlock joints, Renal failure.	Oxalates and nitrates	Pigs, cattle	Common
Pine	Pinus	ponderosa	Ponderosa pine	Moderate -- 1.5 lbs per day	Bark, buds, needles	Causes abortion in pregnant cows, some appear more sensitive	Isocupressic acid	Cattle	Common
Rose	Prunus	virginiana	Chokecherry	High -- 4oz may be lethal to a 100 lb animal	Bark, leaves, and seeds	Blue color in mouth; rapid breathing, gasping; muscular twitching, staggering, convulsions; coma, death within hour after lethal dose	Cyanogenic glycosides	all	Common
Spurge	Euphorbia	esula	Leafy spurge	Low -- rarely grazed	Latex	Gastrointestinal irritation, dermal irritation	Diterpenes	all	Very Rare -- not known to exist in Kittitas County
Spurge	Ricinus	communis	Castorbean	Very High -- 1 oz	All	Gastrointestinal distress, vomiting, bloody diarrhea, shock, collapse, convulsions, death is likely	Lectins (ricin)	all	Very Rare, not known to exist in Kittitas County
St. Johnswort	Hypericum	perforatum	St. Johnswort, goatweed	Moderate -- Sheep - 5% body weight Cattle - 1% body weight	Leaves and flowers	Photosensitization, blisters & scabs around eyes, mouth, ears, nose, and feet; signs develop in 2d to 3wk, death rare	Phenolic compound (hypericin)	cattle, sheep, swine, goats	Common
Sunflower	Acroptilon	repens	Russian Knapweed	Low -- large quantities, cumulative	all, fresh or dry	Chewing disease, head pressing, aimless walking, death from starvation	Unknown sesquiterpene lactone	Horses	Occasional
Sunflower	Centaurea	solstitialis	Yellow starthistle	Low -- Cumulative	all, fresh or dry	Chewing disease, head pressing, aimless walking, death from starvation	Unknown sesquiterpene lactone	Horses	Rare
Sunflower	Senecio	jacobaea	Tansy ragwort	High -- 1 - 5% animal weight, cumulative	all	Liver lesions, staggering, weakness, & death	Pyrrolizidine alkaloids	all	Rare
Sunflower	Senecio	vulgaris	Common groundsel	High -- 1 - 5% animal weight, cumulative, similar to tansy ragwort	all	Acute & chronic liver damage, colic, death; very similar to tansy ragwort poisoning	Pyrrolizidine alkaloids	all	Occasional
Sunflower	Tanacetum	vulgare	Common Tansy	Low -- large quantities	Leaves, stems	Salivating, abdominal pain, colic	Tanecetin	all	Common
Sunflower	Tetradymia	canescens	Horsebrush	High -- 0.5 - 0.75 lbs may cause "bighead" in sheep	Leaves, buds	Bighead in sheep, liver failure, abortion, possibly coma and death in severe cases	Tetradymol	Sheep	Occasional in shrub steppe areas
Sunflower	Xanthium	strumarium	Cocklebur	High -- 0.1 - 0.3% body weight	Seeds & seedlings, fresh or dry	Liver, gallbladder, and gastrointestinal irritation, appetite loss, vomiting, convulsions, death	Glycoside	All, esp. pigs	Occasional
Ornamental Trees and Shrubs
Beech	Quercus	spp.	Oak	Low -- Large quantities, 50% of diet	all, especially leaf buds, flower buds, and acorns	stop eating, become depressed, and develop intestinal stasis. Liver damage, renal damage	Tannins	Cattle sheep, goats, horses and pigs	As ornamentals; rarely found in wild
Dogbane	Nerium	oleander	Oleander	Very high -- 0.005% of body weight	All, fresh or dry, also smoke	Appetite loss, depression, vomiting, stomach pain, irregular heart rate, death	Cardiac glycosides	All	Possible ornamental
Heath	Luecothoe or Kalmia	spp.	Mountain laurel, Sierra laurel	Very high -- 1 oz	all	Irregular heart beat, blurred vision, paralysis, foaming at the mouth, vomiting, colic, coma, death	Diterpenoid compounds	all	Possible ornamental
Heath	Rhododendron	spp.	Rhododendron, Azalea	High -- 0.2% body weight	all	Vomiting, blurred vision, salivation, colic, possibly coma and death	Diterpenoid compounds	All	As ornamentals
Maple	Acer	rubrum	Red maple	High -- 1.5 pounds of leaves	Leaves, especially when fallen, damaged, or wilted.	Breathing difficulties, jaundice, dark brown urine, and death.	unknown oxidant	Horses only	As ornamentals
Pea	Laburnum	anagyroides	Golden Chain Tree	Moderate -- ingestion of seeds or bark will cause symptoms	All, esp. bark and seeds that hang down in pods	Stiffness, staggering gait, convulsions, recumbency, death	Alkaloid (cytisine)	All	Possible ornamental
Pea	Robinia	pseudoacacia	Black & Yellow locust	High -- As little as 6.5oz	All, especially beans and bark	Digestive irritation, depression, paralysis of hindquarters, collapse	Lectins (robin), tannins	All, esp. horses and cattle	As ornamentals
Vervain	Lantana	spp.	Lantana	High -- 1% body weight	Leaves and fruit	Chronic: photosensitization, labored breathing, constipation, swollen eyelids Acute: severe bloody diarrhea, weakness, rapid heart rate, jaundice, death	Triterpenoid compounds	All	Possible ornamental
Walnut	Juglans	nigra	Black walnut	Low -- 5% of bedding with woodchips has caused laminitis in horses	Woodchips, bark, mature fruit	Immobility, depression, elevated temperature, increased heart and respiration rates, edema of lower legs, laminitis	Juglone and unknown toxin(s)	Horses	As ornamentals
Yew	Taxus	spp.	Yew	High -- 0.5 lb	All	Breathing problems, trembling, weakness, heart problems, sudden death	Diterpenoid taxanes	all	Possible ornamental
Mechanical Problems
Cashew	Toxicodendron	spp.	Poison Ivy, Oak		All	Dermal irritation, allergic reaction		All, especially humans	Common
Grass	Bromus	spp.	Brome, Cheatgrass		Awns	Injury to mouth, nose, and eyes		Grazing livestock	Common
Grass	Hordeum	spp.	Barley--foxtail, hare, wild		Awns	Injury to mouth, nose, and eyes		Grazing livestock	Common
Grass	Setaria	spp.	Foxtail--yellow, green, bristly		Awns	Injury to mouth, nose, and eyes		Grazing livestock	Common