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University Library, University of Illinois at Urbana-Champaign

Plants Toxic to Animals

S

Sambucus canadensis (Elderberry)

Description

Elderberry plants are a woody shrub growing about 20 feet tall. The stems are filled with a white pith, and the leaves are opposite, pinnately compound, with lance-shaped serrated leaflets. The flowers are in small flat-topped clusters. Each flowers has about five white petals, and are about 4-6 mm in diameter. Elderberry plants also have drooping clusters of dark purple berries.

Distribution

Elderberry can be found throughout the continental United States, but is more common in the eastern to central states. It prefers moist soils and is frequently found in fields, ditches, and wooded areas. It is also cultivated as an ornamental plant or for use as an ingredient in food or as an herbal medicine.

Conditions of Poisoning

All parts of the plant are poisonous to consume, especially if wilted or in regrowth. Some cases of poisoning in humans occur from using the plant as an herbal medication. Toxicity is largely lost when the berries of the plant are cooked or fermented to make foods like jelly or wine.

Toxic Principle

Cyanogenic glycoside sambunigrin which is hydrolysed in the rumen by microorganisms to free hydrogen cyanide (HCN). The cyanide blocks the action of cytochrome oxidase that prevents hemoglobin from releasing oxygen to the tissues..

Clinical Signs 

An increased heart rate. Increased respiratory rate, panting, open-mouthed breathing, and extreme difficulty breathing. The mucous membranes are bright red. Death results rapidly from asphyxiation. 

Animals Affected

Humans, cattle, sheep, goats

References Used

Burrows, George E., & Tyrl, Ronald J. (2013). Toxic plants of North America. Hoboken: Wiley-Blackwell.

Sanguinaria canadensis L. (Bloodroot or Red Puccoon)

Description

Bloodroot is a low, glabrous, stemless perennial herb. It has extensively branched rhizomes, and each growing tip produces a flower stem and a leaf that is palmately lobed with 5 to 7 lobes. The flower appears from March to May, rolled in a single leaf. The white-to-pink flower has 8-12 oblong petals and numerous golden yellow stamens. The flower is initially taller than the leaf, but as it turns to fruit, the leaf unfolds and flattens to shade the fruit. The root has reddish-orange sap.    

Distribution

Bloodroot grows throughout the mid to eastern states of the U.S. east of the Mississippi and from southern Canada to the northern half of Louisiana and Georgia. It is found in most counties of Illinois in moist but well-drained woodland soil. 

Conditions of Poisoning

All parts of the plant are poisonous but the toxins are most highly concentrated in the root after leaves are completely open. The active alkaloid levels vary greatly between regions as well as populations. 

Toxic Principle

The red-colored latex from this plant contains several alkaloids similar to those found in the Opium Poppy, and include sanguinarine, chelerythrine, protopine, and homochelidonine, as well as resins. 

Clinical Signs

Symptoms of bloodroot poisoning include nausea, vomiting, faintness, dizziness, dilated pupils, fainting, diarrhea, and heart failure. Poisoning can be fatal.

Animals Affected

Goats

References Used

Burrows, George E., & Tyrl, Ronald J. (2013). Toxic plants of North America. Hoboken: Wiley-Blackwell.

https://plants.ces.ncsu.edu/plants/all/sanguinaria-canadensis/

Saponaria officinalis L. (Bouncing Bet)

Description

Bouncing bet is an herbaceous perennial which grows from rhizomes. Its close relative, cow cockle (Saponaria vaccaria L.), is an annual. It grows to be 1-3 feet tall. The stems are erect and jointed with opposite elliptic leaves which are 3-4 inches long and 1/2 to 1-1/2 inches wide at the middle. The leaf margins lack teeth.

The flowers come in clusters of cylindric sepals and bloom from June to September, displaying 5-6 petals notched at the apex. Petal colors range from white to pink. The fruit is a capsule about 1 inch long and 1/4 inch thick containing many somewhat round black seeds. The seeds have minute bumps on the surface.

Distribution

Originally from Europe, bouncing bet and the related species, cow cockle (Saponaria vaccaria L.), grow in open unused areas, along roadsides and railroad tracks, and waste grounds throughout the U.S. Bouncing bet is found in nearly all counties of Illinois, while cow cockle is limited only to scattered counties in northern and central Illinois. Bouncing bet and cow cockle are considered weeds, although they are attractive plants.

Conditions of Poisoning

The abundance of bouncing bet along roadsides and in other wastelands makes it easily accessible to animals allowed to graze in such places. Although the entire plant is poisonous, the seeds contain the largest concentration of the toxic principle.

Control

Screenings of grain should be checked for large quantities of Saponaria seeds. Animals tend to avoid contaminated feed because the plants apparently are distasteful. Animals should not be grazed where Saponaria species is abundant, especially when the pasture grasses are present in short supply or are exceedingly dry. 

Toxic Principle

Bouncing Bet contains large amounts of saponins, which froth when extracted with water. The saponins are soluble in water and alcohol. The sapotoxins of these saponins are similar or identical to those of corn cockle (Agrostemma Githago). Hydrolysis of the saponins yields sugars and sapogonins, a group of physiologically active substances.

The toxic material is contained in highest concentration in the seeds. Most animals refuse to eat the seeds and avoid grains or screenings containing them. Feeding of the plant itself to sheep in an amount of 3% of the body weight caused death within 4 hours; the plant weight being expressed on a dry-weight basis.

Clinical Signs

Poisoning caused by bouncing bet is usually mild, as animals tend to avoid the feed that contains this plant. The poison irritates the digestive tract and may cause vomiting, signs suggestive of nausea, and diarrhea. Slowed or rapid breathing as well as unsteadiness, ataxia and coma also are associated with poisoning by this plant.

Animals Affected

Cattle, sheep, horses

Solanum carolinense L. (Horse Nettle or Bull Nettle)

Description

Horse Nettle grows to be about 1-2 feet tall, and has yellow spines on the stems and leaves. Both the leaves and flowers are simple, alternate, oblong, and irregularly lobed. The flowers are in clusters at the top of the plant, ranging from pale violet to white in color. The berries are about 1-1.5cm in diameter and are yellow when they're ripe. Flowers appear in June to August, are light purple to white, 3/4 to 1 inch across, and in short racemes near the top of the plant. Petals are united with 5 points at the margin. Fruits are globose, about 1/2 inch in diameter and yellow when mature. Yellow or brownish seeds are numerous, and irregularly circular, about 1/8 inch across. 

Distribution

Horse Nettle is found throughout the Southern United States, as well as parts of the Midwest and Northeastern states. In particular, it is a perennial weed of disturbed soils and unused areas along roads and field edges, especially of the southern States. It is a common weed in all counties of Illinois.

Conditions of Poisoning

Poisoning occurs primarily when animals are confined in overgrazed fields or where nightshade is abundant. The hazard of poisoning varies depending on the plant species, maturity of plants, and other conditions. Generally, the leaves and green fruits are toxic. Ingestion of juice from wilted leaves may be especially toxic and sometimes deadly. Many cases of poisoning have been reported as a result of eating green berries. Green berries have produced severe intestinal, oral and esophageal lesions in sheep. Cattle reportedly seek out the berries of Solanum species and will eat the green plant, specially when other green forage is unavailable.

Control

Animals should be kept away from fields with heavy infestation of nightshade. Plants should be mowed or pulled up while in flower, and burned. Remove green parts of potatoes before cooking, eat only ripe tubers.

Toxic Principle

Tropane alkaloids, especially solanine, which has similar effects as atropine on the autonomic nervous system. Also directly irritating to the oral and gastric mucosa. Green plant and unripe fruits are the most toxic. Toxicity is reduced by drying.

Clinical Signs

Nausea, vomiting, salivation, drowsiness, abdominal pain, diarrhea, weakness, respiratory depression; may be fatal.

Animals Affected

Horse, cattle, goats, sheep, pigs, rabbits

References Used

https://plants.ces.ncsu.edu/plants/all/solanum-carolinense/

Solanum spp. (Nightshade)

Description

About 1,500 Solanum species exist in the world, and they include some of the most common garden plants such as potato (Solanum tuberosum L.) and eggplant (Solanum melongena L.). One of the species, Jerusalem cherry (Solanum pseudocapcicum L.) is grown as a house plant for its compact form and small round berries which turn bright red at maturity. The tomato (Lycopercison esculentum Mill.) is also a related plant. Included in this entry are descriptions of Black Nightshade, Bittersweet Nightshade, Silverleaf Nightshade, and Horse Nettle. Horse Nettle also has its own expanded entry, and other related species may be found under their own names.

Bittersweet Nightshade (S. dulcamara)

Bittersweet nightshade is also known as European bittersweet or climbing nightshade. This plant grows from rhizomes and is a slender climbing or trailing perennial reaching 6 feet in length. Leaves are alternate, ovate, simple or deeply lobed, 1-1/2 to 4 inches long, and pointed at the tip. Flowers are deep purple or bluish purple with flower stalk arising between the leaf nodes or opposite the leaves. Nearly round fruits turn red when mature and stay on the vines through mid winter.

Black Nightshade (S. nigrum)

Black nightshade is an annual herb with a tap root. Stems are erect and much branched reaching 3 feet tall. Leaves alternate, ovate or lanceolate, and long-stalked. The flower has 5 white petals, sometimes with a yellow inner star, and ranges from 1/4 inch to 3/8 inch across. Berries are round and about 1/4 or so inches across, green, and turn purplish to black when ripe. Immature berries and foliage are toxic, but ripe fruits are reportedly edible.

Plants commonly known as black nightshade may include two native species, American Black Nightshade (S. americanum P. Mill.) and Eastern Black Nightshade (S. ptycanthum Dun.), as well as S. nigrum which was introduced from Europe and is widely naturalized. Solanum ptycanthum may be more commonly found in the midwest since S. americanum appears to be more concentrated in the southern states.

Horse Nettle, Bull Nettle (S. carolinense) ​

A perennial with a deep taproot and rhizome below ground. Its stem and leaves have yellowish spines and sometimes are hairy. Leaves are alternate and ovate with irregularly wavy or lobed margins. Flowers appear in June to August, are light purple to white, 3/4 to 1 inch across, and in short racemes near the top of the plant. Petals are united with 5 points at the margin. Fruits are globose, about 1/2 inch in diameter and yellow when mature. Yellow or brownish seeds are numerous, and irregularly circular, about 1/8 inch across. 

Silverleaf Nightshade or White Horse-Nettle (S. elaeagnifolium)

This perennial herb gets its common name because of its silvery appearance caused by the numerous fine hairs. Its thick, lanceolate leaves are wavy and roughly indented (sinuate). The stems and parts of the leaves have short stiff spines. The flowers appear at the end of branches and have petals which are pale to deep blue or lavender in color.

Distribution

Bittersweet Nightshade (S. dulcamara)

An introduced species from Eurasia, this plant is found in moist ground of low woods, roadsides, fence rows and thickets. It ranges from Nova Scotia to Minnesota through much of the Midwestern states and south to Florida and Texas. In Illinois, this plant is commonly found in the north-eastern counties including Champaign.

Black Nightshade (S. nigrum)

The native species, S. americanum, is usually found in undisturbed habitats or moist open woodlands, stream banks, valleys, fields, roadsides and waste places throughout the east central United States from Maine to Florida and west to Minnesota, Nebraska and Oklahoma. It is found in almost all counties of Illinois. The introduced species, S. nigrum, is rare in Illinois but abundant in some places from Minnesota and the Dakotas to Oklahoma.

Horse Nettle, Bull Nettle (Solanum carolinense L.)

This plant is found in waste spaces or neglected fields, gardens, and roadsides from the Atlantic coast to Texas, north to South Dakota and as far south as Florida. It is a common weed in all counties of Illinois.

Silverleaf Nightshade or White Horse-Nettle (S. eleagnifolium)

Silverleaf Nightshade is found in large colonies in open woodlands, pastures, stream valleys, roadsides and disturbed or waste grounds in the Southwest from Missouri to Kansas, Oklahoma, Texas, Arizona, New Mexico and southwestern Colorado. This plant is found in a a few counties of Illinois, but a similar species (S. carolinense) is easily mistaken for this plant. 

Conditions of Poisoning

Poisoning by these Solanum species occurs primarily when animals are confined in overgrazed fields or where nightshade is abundant. The hazard of poisoning varies depending on the plant species, maturity of plants, and other conditions.

Generally, the leaves and green fruits are toxic. Ingestion of juice from wilted leaves may be especially toxic and sometimes deadly. Many cases of poisoning have been reported as a result of eating green berries. Green berries have produced severe intestinal, oral and esophageal lesions in sheep. Cattle reportedly seek out the berries of Solanum species and will eat the green plant, specially when other green forage is unavailable. Silverleaf nightshade (S. eleagnifolium) is exceptional in that the ripe fruit is more toxic than the green. S. eleagnifolium is toxic at only 0.1% of the body weight. Toxicity is not lost upon drying. Solanine content increases up to maturity. Solanine, except in potatoes, is reportedly destroyed by cooking. Potato (S. tuberosum) peelings contain the major portion of the toxic principle in the tuber, and leaves, sprouts and vines. Sun-greened potatoes are especially toxic. Spoiled potatoes and peelings also have caused severe poisoning. Cooking does not appear to destroy all the alkaloids in greened potatoes. Toxicity may vary with the soil, climate and other variables. Animals may browse potato plants or eat sprouted potatoes, leading to problems. 

Control

Animals should be kept away from fields with heavy infestation of nightshade. Plants should be mowed or pulled up while in flower, and burned. Remove green parts of potatoes before cooking, eat only ripe tubers.

Toxic Principle
  • Many contain the steroidal glycoalkaloid solanine. Upon hydrolysis, a sugar and the alkaloid solanidine are recovered. The free (unconjugated) steroidal alkaloid (the aglycone) is the primary form acting on the nervous system.
  • Other aglycones present may include dihydrosolanidine, tomatidine and strophanthidin. Toxic properties of these compounds are characteristic of saponins.
  • Some of these plants also have cardiac effects, e.g., Jerusalem cherry (S. pseudocapsicum) contains an additional alkaloid, solanocapsine, which produces bradycardia.
  • In some plants, atropine-like constituents predominate, e.g., potato (S. tuberosum), and some strains and stages of black nightshade (S. nigrum).
Clinical Signs

Clinical signs vary with irritant effect caused by the intact glycoalkaloid or saponin, and the nervous effects of the alkaloid. Irritant effects include hypersalivation, anorexia, severe gastrointestinal disturbances, with diarrhea that is often early and hemorrhagic. The nervous effects include apathy, drowsiness, depression, confusion, progressive muscular weakness, numbness, dilated pupils, trembling, labored breathing, nasal discharge, rapid heartbeat, weak pulse, bradycardia, central nervous system depression, and incoordination, often accompanied by paralysis of the rear legs. Coma may occur without other nervous signs. High doses may cause intestinal stasis and constipation. Hemolysis and anemia, possibly a result of saponins, have been reported, with renal failure in severe cases. Terminal signs include unconsciousness, shock, paralysis, coma, circulatory and respiratory depression, and death. The course varies from sudden death to 3-4 days of illness which may terminate in death or recovery. In less acutely poisoned animals, there may be yellow discoloration of the skin in unpigmented areas, weakness, incoordination, tremors of the rear legs, anemia, rapid heart rate and bloat.

T

Taxus cuspidata Sieb. & Zucc. (Japanese Yew)

Description

Japanese Yew is an evergreen shrub with dark green leaves. The leaves grow alternately, with stiff, flat and needle-like leaves. The leaves grow from 1/2 inch to 1 inch long. Japanese Yew's berries are bright red and egg-shaped. It is a very common oriental shrub across North America. The shrubs grow up to 20 feet tall.

Distribution

Though Japanese Yew was originally imported to the United States, it is now found throughout the country because of it being cultivated in both landscape architecture and design. In particular, the plant is found in the Northwestern United States and is widespread across the East Coast and throughout the Midwest. 

Conditions of Poisoning

Consuming Yew introduces several toxins into the body. All parts of the plant are toxic. The plant is toxic year-round, with a higher level of toxicity occurring at the end of the year because there's been time for the toxin to build up in the plant. Both fresh and dried yew is toxic. 

Control

Animals should not be allowed to graze near where Japanese Yew is growing. 

Toxic Principle

Japanese Yew has a wide variety of toxins, including Taxine A and Taxine B, and Oil of Yew. Both Taxins are found in all parts of the plant except the fruit. Oil of Yew is found in the Yew's sap, and is an intestinal irritant that is the cause of colic and diarrhea symptoms of yew poisoning.

Clinical Signs

There are two syndromes of Japanese Yew poisoning an animal can exhibit--Acute and Subacute. The primary symptom of Acute Syndrome is death, which usually occurs 1-3 hours after consuming the Yew. The symptoms of Subacute Syndrome include Ataxia, diarrhea, hypotension, colic, hypothermia, coma, seizures, weakness, respiratory failure, bradycardia and sudden death. Most animals usually die within 24-48 hours of consuming the yew. 

Animals Affected

All animals

References Used

http://poisonousplants.ansci.cornell.edu/yew.html

Toxicodendron radicans (L.) Kuntze (Poison Ivy)
(=Rhus toxicodendron L., Rhus radicans L.)

Description

Poison ivy is a perennial, woody plant that can grow as a climbing vine or as a low upright or trailing shrub. Leaves are split into three leaflets, alternate, glossy, hairless, and may be toothed or lobed. Leaves turn red in the fall. Climbing plants produce aerial roots that grasp the climbing surface, generally the bark of a tree. Flowers are small, greenish-white, and grow in hanging clusters. Fruits are yellowish-white waxy berries.

Distribution

Poison ivy is native throughout the United States and southern Canada, although it is less common on the West Coast where poison oak is more prevalent. It grows in a wide variety of soils and locations including waste areas, woodlands, thickets, roadsides, clearings, and fencerows. 

Conditions of Poisoning

Poison is typically delivered through skin contact with the plant, although indirect contact, such as touching an animal or object that has rubbed against the plant, will also deliver the toxin. All parts of the plant are poisonous, including the berries. Smoke from burning poison ivy can contain the toxin and affect people who are allergic to it.

Control

Plants and root systems should be carefully dug up while using plastic gloves and keeping skin fully covered. Plants should be disposed of in a plastic bag, and should never be burned. Herbicides specifically for poison ivy can be purchased, but may not be cost-effective when dealing with a large infestation. Other pesticides such as glyphosate can be used selectively on poison ivy plants, but care should be used not to spread the pesticide to desired plants. Sheep and goats can eat poison ivy without any known problems, so allowing them to graze in areas infested with poison ivy can also help reduce the presence of the plant.

Toxic Principle

Urushiol, an oily, resinous toxin found in all parts of the plant. Drying does not decrease toxicity.

Clinical Signs

Redness of the skin, irritation, itching, swelling, blisters. Symptoms may be severe.

Animals Affected

Humans. Animals are largely unaffected by poison ivy, so the primary concern is generally secondary contamination from an animal that has rubbed against the plant and is then touched by a person.

Reference Used

Knight, A. P., & Walter, R. G. (2001). A guide to plant poisoning of animals in North America. Jackson, Wyo.: Teton NewMedia.

https://plants.ces.ncsu.edu/plants/all/toxicodendron-radicans/

http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/weeds/poison-ivy.aspx

Tulipa spp. (Tulip)

Description

Tulips are a popular spring ornamental that are often grown as an indoor or garden plant. The leaves of the plant are long, narrow, and alternate. The flowers often grow singularly and have six tepals that can be any of a wide range of colors except for true blue. The tepals often grow in the shape of a cup, although bowl, goblet, and star shapes also exist, and the edges of the tepals may have ruffles or fringe. The plant grows from a papery, teardrop-shaped bulb that resembles and is sometimes mistaken for an onion.

Distribution

Tulips can be found as cultivated plants across North America, but the plants can occasionally be found naturalized in the wild as well. Tulipa sylvestris can sometimes be found in fields, waste areas, and roadsides in the northeastern portion of the United States, and Tulipa clusiana has been seen in the southwestern United States in California.

Conditions of Poisoning

Poisoning can occur after consumption of the flowers, stem, or bulb of the plant, although the bulb has the highest concentration of the toxin. Skin contact can sometimes cause irritation, although effects are usually quite mild.

Toxic Principle

Tulipalin A and B.

Clinical Signs

Vomiting, hypersalivation, depression, diarrhea, stomach pains. Skin irritation is characterized by tingling, redness, and blisters that may spread beyond the point of contact, but effects are usually mild and brief.

Animals Affected

Humans, dogs, cats, horses

References Used

Burrows, George E., & Tyrl, Ronald J. (2013). Toxic plants of North America. Hoboken: Wiley-Blackwell.

https://plants.ces.ncsu.edu/plants/all/tulipa-spp/

http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c252

https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/tulip

X

Xanthium strumarium L. (Cockleburs)

Description

The cocklebur plant is a coarse herbaceous annual about 3 feet high. They have erect, stout stems and spreading branches that are angled and often red-spotted. The leaves are alternate, rough to the touch, and broadly triangular to heart-shaped. Cockleburs produce two kinds of flowers. One kind, in short terminal branches, produces only pollen; the other kind, in clusters in the axils of the leaves, produces seed. The fruit is a small, hard, 2-chambered bur, oval in shape and about 3/4 inch long. It is covered with strong, hooked spines. This plant reproduces only by means of its seed. 

The seedling, the plant's most dangerous stage, is very different from the mature plant. It consists of a slender, straight whitish green stem 1 to 3 inches tall. Capping this stem are two strap-shaped green leaves, each about 1 1/4 inches long and l/4 inch wide. Leaves produced after these first leaves gradually assume the characteristic shape of those of the mature plant. Proof of the identity of young seedlings may be found in their attachment underground to the easily recognized burs from which they sprout.

Distribution

Cockleburs occur throughout Illinois and the rest of the U.S. as stray plants in waste places, cornfields, pastures, and along roadsides, fencerows, stream banks, the beds of dry ponds, and previously flooded land along streams and rivers. Pastures and meadows may be heavily infested, especially with the seedling stage as the result of the burs having been washed in from adjoining fields.

Conditions of Poisoning

Pigs rooting and grazing in cocklebur infested places are the most often poisoned domestic species, with those weighing between 20-50 pounds being the most susceptible. Poisoning also affects cattle, sheep, horses, and fowl.

The plant is most hazardous at the seedling stage because of its toxicity as well as palatability. Ingestion of young seedlings in the amount of 0.75% of the animal's weight may result in clinical signs of toxicosis in a few hours and death in 24-48 hours. Approximately 500 seedlings was lethal to a 40-pound pig. The seeds are poisonous at 0.3% of animal weight but are seldom eaten because of their spiny capsule. Occasionally the eating of the ripe spiny capsules is said to result in intestinal obstruction. Mature plants, however, are seldom eaten, perhaps because of their bitterness and rough texture.

Control

Animals should be kept out of infested grazing grounds and drinking places during late spring and early summer when cocklebur seeds are sprouting. Plants in crop fields and pastures may be removed by hoeing and weeding. Heavily infested places should be mowed before the plants form seeds.

Toxic Principle

Carboxyatractyloside, a sulfated glycoside, which is present in high concentrations in the seed and cotyledon, is now believed to be the primary toxic principle. As plants develop past the seedling stage, their toxicity decreases. The seeds and seedlings of cockleburs contain the glucoside xanthostrumarin. Toxicity is not lost on drying.

Clinical Signs

Clinical signs usually appear within 2-24 hours after ingestion and may be followed by death within 3 days after the onset of illness. Signs most often include anorexia, reduced responsiveness, vomiting, rapid weak pulse, dyspnea, muscular weakness, prostration, and spasmodic contraction of leg and neck muscles. Ascites and potentially lethal hypoglycemia may occur.

Pigs display signs consistent with abdominal pain, and if severely poisoned may show opisthotonos, spasmodic running motions followed by convulsions and death after about 48 hours.

Cattle may become blind, develop extreme hypersensitivity to external stimuli and prominent convulsions. Calves die acutely, often within 12 hours.

Fowl show markedly reduced response to external stimuli which may be followed by death.

Animals Affected

Pigs, cattle, fowl, rodents