POISONOUS PLANTS S / T / W / Y

SENSITIVE FERN(Onoclea sensibilis)

This plant,is native to Canada, but is also found elsewhere and is often abundant in low, wet areas.

Poisonous principles and symptoms
The leavers are toxic with an unknown chemical. When the fronds (aboveground leaves) are included in hay, they produce toxic symptoms in horses. The fertile fronds (spore-bearing stalks) are also included in hay. A literature search did not reveal any reports on the toxin, nor was the plant organ that contains the toxin identified. Symptoms of poisoning include congestion of brain, unsteady gait, colic, unable to stand without falling, incoordination, and death. Ingesting hay containing sensitive fern produces the following symptoms: difficulty in eating, falling down, walking as if blind, rubbing against objects, and death. Postmortem examination showed extreme icterus, swollen liver, paralysis of the alimentary tract, and brain edema. Old horses are more affected than younger ones. Horses that are worked and are fed a grain supplement, in addition to hay that includes the fern, are not affected. Recovery may occur if the horses are given good hay and grain before serious nervous symptoms .

SNEEZEWEED (Helenium autumnale)

clusters of numerous medium sized bright gold flowers grow on branching stalks at the top of the plant. These perennial, open, branching plants are up to 4 feet tall, with up to 6 inch leaves which are attached directly to the stem and run down the sides of it.

Poisonous principles and symptoms
The leaves and stems contain Helenalin, a sesquiterpene lactone, is the major toxin found in sneezeweed. Symptoms of poisoning include convulsions, incoordination and weakness.

SORGHUM (Sorghum bicolor)

A cultivated plant grown as ensilage, poultry feed, or sometimes as broomcorn for its long, flexible, high-quality broom fibers.

Poisonous principles and symptoms
The stems and leaves contain dhurrin. In the presence of plant enzymes released by damage, a cyanogenic glycoside, dhurrin, produces hydrocyanic acid (HCN) in the animal''s system. Levels of cyanide at 250 mg/100 g of plant tissue have been measured after damage. A lethal dose of cyanide is 0.5-3 mg/kg of body weight. Some sorghum plants have been measured with levels 10 times a lethal of HCN . Symptoms of poisoning include An inability to retain urine voluntarily, abortion and incoordination.

SORREL (Rumex spp.)

Sheep's sorrel is quite common on both waste and cultivated land, growing to a height of around 30 centimetres. It is found on mainly acid soils and is vertually unseen on calcareous land. Common sorrel (pictured above) is the same as sheep's sorrel but larger reaching a height of around 1 metre and is more tolerant of chalky soils.

Poisonous principles and symptoms
while other toxic substances like glycosides are present in both species, ingestion of oxalates is commonly regarded as being Sorrel's poisonous principle. When animals who have eaten this plant and become ill, they have shown symptoms that are consistant with oxalate poisoning like staggering, inability to rise, muscle spasms and abnormal breathing. The plants are tasteless and it is often eaten in quantity with no affects on the animal at all, making the conditions in which poisoning occurs not clear enough to define.

SPREADING DOGBANE (Apocynum androsaemifolium)

A busy plant that reaches a height of 30 to 120 centimetres, with numerous small pink, nodding, bell-like flowers, fragrant and striped inside with deeper pink. Milky juice exudes from broken stems and leaves. The leaves are smooth, opposite, ovate, blue-green, 2-4" (5-10 cm) long and the fruit is 2 long, slender seed pods, 3-8" (7.5-20 cm) opening along one side, with seeds ending in a tuft of hair.

Poisonous principles and symptoms
The stalk and leaves are poisonous containing apocynamarin, a cardiac glycoside, as well as other glycosides and resins. It can cause death to the animal.

SPURGE (Euphorbia spp.)

There are more than 1600 species of spurge. The plant is common on waste and uncultivated land. It gets its name from Euphorbius, physican to King Juba II of Mauritania in A.D. 18. Its seeds are commonly used in medicine of that time as a laxative.

Poisonous principles and symptoms
Many of the different Spurge species contain a milky latex which is believed to be its main toxic principle. There are also resins, glycosides and other toxic substances present in some species. Spurge has caused poisoning amongst horses in Australia and New Zealand. Symptoms of poisoning includes severe swelling and inflammation of the mouth, salivation and diarrhoea.

STAR OF BETHLEHEM (Ornithogalum umbellatum )

This perennial is a close relative of wild garlic (but without the smell). It reproduces mostly by clumps of bulbs. The central flower stem grows 4 to 12 inches long. The leaves are about as long as the stem and have a light green midrib. Star-shaped flowers, six white petals with green stripes on the back, appear in spring. Usually the tops die back after flowering and before the fruit, a capsule, can be produced. Originally introduced to Indiana as a garden plant, star-of-Bethlehem has now gone wild along roadsides, in fields, and in woods.

Poisonous principles and symptoms
All parts of this plant especially the bulb contains cardiac glycosides in all parts of the plant, with the bulbs containing a higher percentage of the toxin. This is not a commonly reported toxicosis, but it can be severe if encountered and if enough of the bulbs have been consumed. The bulbs may become more readily accessible after plowing, frost heaving or other such activity, thus increasing the risk of toxicosis. The toxic component (and therefore the toxic signs) are very similar to foxglove (Digitalis). Symptoms of poisoing include stomach and intestinal irritation, which is followed by abnormalities in the heart's rate and rhythm, and this can progress to fatal cardiac arrythmias.

ST JOHN'S WORT (Hypericum perforatum)

A herbaceous perennial growing freely wild to a height of 1 to 3 feet in uncultivated ground, woods, hedges, roadsides, and meadows; short, decumbent, barren shoots and erect stems branching in upper part, glabrous; leaves pale green, sessile, oblong, with pellucid dots or oil glands which may be seen on holding leaf to light. Flowers bright cheery yellow in terminal corymb. Calyx and corolla marked with black dots and lines; sepals and petals five in number; ovary pear-shaped with three long styles. Stamens in three bundles joined by their bases only. Blooms June to August, followed by numerous small round blackish seeds which have a resinous smell and are contained in a three-celled capsule; odour peculiar, terebenthic; taste bitter, astringent and balsamic. There are many ancient superstitions regarding this herb. Its name Hyperieum is derived from the Greek and means 'over an apparition,' a reference to the belief that the herb was so obnoxious to evil spirits that a whiff of it would cause them to fly.

Poisonous principles and symptoms
Its flowers and leaves contain hypericin, a fluorescent pigment that is regarded as a derivative of naphthodianthrone. The pigment is contained in small black dots that are just visible to the naked eye on leaves and petals. The chemical is a primary photosensitizer because the photodynamic action occurs in the skin. The reaction is more severe if fresh plants are eaten, but dried plants can also cause photosensitization, even though 80% of the hypericin is lost. Symptoms of poisoning include skin peeling off, loss of appetite, staggering and coma.

SWEAT PEA (Lathyrus odoratus)

These hardy annuals and perennials may be climbing or bushy. The climbing vines grow up to 6 feet high and the dwarf bushy kinds, 1 to 2 feet high. the flowers of the Sweet Pea are usually purple, but other colors have been developed. Sweet Peas are classed in four main groups: the Ruffled varieties, which are great for the garden; the Multiflora varieties, which have many flowers on each stem; the Cuthbertson varieties, which are a heat-resistant, spring-flowering type; Early-flowering varieties, which are used for producing winter blooms in the greenhouse and for fall planting in mild climates.

Poisonous principles and symptoms
Its seeds contain beta-aminoproprionitrile. ), which causes osteolathyrism, a syndrome characterized by skeletal deformities and aortic rupture. This chemical was first extracted from sweet pea plants and has since been found in some other members of the genus Lathyrus. Horses are more susceptible to this syndrome than other livestock. Symptoms of poisoning include rigid gait, alateral curvature of the spine and localized abnormal dilation of a blood vessel filled with fluid or with clotted blood.

TALL FESCUE (Festuca arundinacea )

When tall fescue first arrived in the United States during the 1940s, it was considered a wonder grass. It was easy to establish, it yielded a good amount of forage, it was tolerant of a wide range of management regimens, and it could handle a variety of climatic conditions as well as sustain heavy foot traffic. Farmers and ranchers embraced the new grass with great enthusiasm and, in a relatively short span of time, some 35 million acres of land in the United States was planted with tall fescue. Then, the honeymoon ended. Horse breeders noticed that they were having foaling problems with some mares which were grazing tall fescue grass or being fed tall fescue hay.

Poisonous principles and symptoms
In the late 1970s, it was discovered that much of the tall fescue grass in pastures contained a fungal endophyte that can have highly deleterious effects on the animals consuming it. The scientific name for this fungal endophyte is Acremonium coenophialum. Agriculture turned to research to find out why these things were happening. In the late 1970s, it was discovered that much of the tall fescue contained a fungal endophyte that can have highly deleterious effects on animals consuming it especially pregnant mares. Its effect on pregnant mares can be particularly severe. Mares grazing on infected tall fescue pasture or fed infected tall fescue hay might have prolonged gestation or a tendency to abort, can develop an abnormally thick and/or tough placenta, can retain the placenta after giving birth, often have difficulty in the birthing process (dystocia), and might have no milk (agalactia) for the foal once it is born--if, indeed, the foal is born alive and remains alive after birth.

TALL LARKSPUR (Delphinium glaucum)

A very tall 4 to 6 foot robust plant, main stem which is frequently purplish is topped by many purplish-blue flowers. Leaves, 3-5 deeply toothed pointed lobes.

Poisonous principles and symptoms
The whole plant contains Methyllycaconitine, a diterpene alkaloid that is considered to be the most toxic of the alkaloids occurring in larkspurs that are likely to be grazed by cattle on rangelands. Many other alkaloids occur in larkspurs, but they are much less toxic than methyllycaconitine. No symptoms documented.

TANSY (Tanacetum vulgare)

These old-fashioned garden plants were introduced from Europe and are now found in old gardens or along roadsides, creek banks, and waste areas. They are perennial herbs from a short, stout rootstock and bear alternate fern-like leaves with saw-toothed margins. The yellow, strong-scented, bitter-tasting flowers are in flat-topped clusters at the tops of the plant.

Poisonous principles and symptoms
This is not a commonly reported toxic plant. Animals rarely ingest it, and this plant rarely occupies significant acreage in pastures. The leaves and stems are poisonous containing an oil tanecetin. Symptoms of poisoning include salivating, abdominal pain (colic), with the possibility of convulsions and abortions occurring.

THORN APPLE (Datura stramonium)

The Thornapple is, like the Henbane, a member of the order Solanceae. It belongs to the genus Datura, which consists of fifteen species, distributed throughout the warmer portion of the whole world, the greatest number being found in Central America. Nearly all of them are used locally in medicine, and are characterized by similar properties to those of the official species, Datura Stramonium. The plants vary from herbs to shrubs, and even trees. Also known as Jimsonweed (jamestownweed). It received that common name in 1697 soldiers who ate the plant as a vegetable began behaving extremely oddly due to its hallucinogenic properties.

Poisonous principles and symptoms
The thorn apple contains the alkaloids hyoscyamine and hyoscine, which it present in the whole plant. Symptoms of poisoning include restlessness, incoordination, pupil dilation, paralysis, an increased respiration and death can occur. Due to the plants unpleasant aroma and taste it is unattractive to animals and poisoning is rare.

TOBACCO (Nicotiana spp.)

These tall annual plants grow from fibrous roots and produce large, hairy leaves and terminal clusters of tubular, 2 inches long, white, red, lavender, or yellow flowers on short stalks. Many-seeded capsules may appear in late summer. The tobacco species with colorful flowers are grown as garden ornamentals.

Poisonous principles and symptoms
The leaves contain the toxin nicotine, an alkaloid with an irritating effect on the stomach and intestines and also the nervous system. This toxin is related to the toxins in poison hemlock and lupine. The initial signs of poisoning can develop within 10 to 15 minutes or may not manifest for several hours. At first, the irritating effect that tobacco has on the stomach and intestines will cause salivating and diarrhea. Shortly after the digestive signs develop, neurologic signs appear. Initially, nicotine stimulates the nervous system, with depression of the nervous system occurring at a later time. Early signs include nervousness, shaking, trembling, a stiff and uncoordinated gait, weakness and collapse. Cardiac abnormalities may be noted as well as breathing difficulties, to the point of respiratory paralysis (the cause of death in lethal cases). Tobacco is also teratogenic, causing birth defects if the mother animal was pregnant when the toxicosis occurred.

WHITE BRYONY (Byyonia dioica)

A perennial climbing plant; the prickly stem grows to a length of 10 feet and climbs using spiral tendrils that grow opposite to the leaves. The rootstock is dirty white, spindle-shaped and fleshy and contains milky juice. The leaves are cordate, five-lobed, and rough. Small, greenish-white or yellowish flowers grow in axillary corymbs from June or August. The fruit is a black, pea-sized berry.

Poisonous principles and symptoms
It is unclear what the poisonous principles of this plant are but they are believed to be associated with a glycoside and an alkaloid. Symptoms of poisoning include digestive disturbance with acute diarrhoea, profuse urination and sweating, respiratoy difficulty, incoordination, convulsions and occasionally cessation of defecation. Affected horses are markedly unwilling to move. There have been reports of poisoning in horses.

WHITE SNAKEROOT (Eupatorium rugosum)

A common perennial of shady, moist woodlands and wood edges. It often goes unnoticed because flowering does not begin until July or later. Stems are tall and mostly smooth, with opposite, long-petioled leaves. Leaf blades are generally egg-shaped, with sharply toothed margins and three prominent veins. Small white flowers are borne in loose spreading clusters.

Poisonous principles and symptoms
The toxic compound, tremetol, is found in the leaves and stems of white snakeroot and is at peak concentrations in summer through fall. Tremetol is unusual in that it is a fat-soluble molecule that becomes concentrated in the milk of lactating animals. Signs of poisoning begin with trembling in the leg muscles. Other symptoms include sweating, labored and rapid breathing, constipation, depression, stiff gait, dilated pupils and weakness. Death may be sudden. Milk sickness, caused by drinking milk produced by animals that have eaten white snakeroot, is of historical significance because this affliction reportedly killed Abraham Lincoln�s mother.

WOODY NIGHTSHADE(Solanum dulcamara)

This plant is sometimes found on waste grounds, but often seen climbing over hedges and woodland trees. This perennial plant which dies back in the winter bears oval green berries that turn red when they are ripe. Bittersweet is another common name for this plant.

Poisonous principles and symptoms
The whole plant contains solacine which is an alkaloidal glycoside. Symptoms of poisoning include nervous excitement, rapid pulse and respiration, dilated pupils, green diarrhoea, staggering and falling down. Poisoning is very uncommon and there have been no recent reports.

YELLOW STAR-THISTLE(Solanum dulcamara)

An extremely prickly plant, up to 3 feet tall, which starts as a basal rosette of deeply-lobed, white-woolly leaves. The flowers (solitary at the end of branches) have outward pointing, stiff, inch-long spines. Introduced from the Mediterranean region, this plant takes over rangelands, roadsides, pastures, and fields.

Poisonous principles and symptoms
The whole plant is toxic to horses while unfortunately the exact toxic principle is unknown it causes nigropallidal encephalomalacia or chewing disease in horses(the human equel being to Parkinson's disease). The compound only affects horses and permanently damages the area of the brain that controls fine motor movements, including mouth and lip movements. Toxicity effects are uncurable one clinical signs appear. Signs of poisoning include incoordination, reduced water intake and death.

YEW (Taxus baccata)

Cultivated in gardens this tree is 40 to 50 feet high, forming with age a very stout trunk covered with red-brown, peeling bark and topped with a rounded or wide-spreading head of branches; leaves spirally attached to twigs, but by twisting of the stalks brought more or less into two opposed ranks, dark, glossy, almost black-green above, grey, pale-green or yellowish beneath, 1/2 to 1 1/2 inches long, 1/16 to 1/12 inch wide. Flowers unisexual, with the sexes invariably on different trees, produced in spring from the leaf axils of the preceding summer's twigs. Male, a globose cluster of stamens; female, an ovule surrounded by small bracts, the so-called fruit bright red, sometimes yellow, juicy and encloses the seed. No tree is more associated with the history and legends of Great Britain than the Yew. Before Christianity was introduced it was a sacred tree favoured by the Druids, who built their temples near these trees - a custom followed by the early Christians. The association of the tree with places of worship still prevails.
Yew contains a number of toxic alkaloids which are rapidly absorbed from the digestive tract and affect the action of the heart. The alkaloids are present in all parts of the tree except the fleshy berries, and they are not depleted by drying, this making yew clippings extremely poisonous still. Some confusing information exists concerning the toxic properties of yew, some suggesting that it may be fed as a fodder in some circumstances. However, there is no doubt that it can be deadly expecially during the winter monts. Symptoms of poisoning include incoordination, coldness, rapid then weak pulse, excitability prior to collapsing. In many cases there are no symptoms and sudden death occurs within a few hours of ingestion. There have been many cases of poisoning reported.

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