Poisonous Plants

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GENUS: Quercus

Quercus spp.—0aks

FAMILY: Fagaceae—the Beech Family

This economically important family contains the oaks, beeches, chestnut, and numerous other genera of trees. Characteristic features include leaves: alternate, simple, often toothed or cleft (lobed); male flowers: solitary or clustered.

PHENOLOGY: The oaks generally flower in mid-spring, the flowers appearing before the leaves.

DISTRIBUTION: Oaks are familiar trees found in a diversity of habitats from swamps to dry upland woods.

PLANT CHARACTERISTICS: Oak trees are very common and probably recognized by most readers; leaves: pinnately nerved; fruit: an acorn.

POISONOUS PARTS: Acorns and young shoots can cause severe poisoning, especially if eaten in quantity.

SYMPTOMS: Livestock display the following symptoms: anorexia, initial constipation (hard, dark fecal pellets) passing into diarrhea if the animal lives, gastroenteritis, thirst, and excessive urination.

Postmortem: gross lesions: lower half of digestive tract displays mucoid enteritis. becoming hemorrhagic; edema of mesenteric lymph nodes; subcutaneous edema and increased peritoneal and plural fluids; congested liver; gallbladder distended with viscid, brown bile; kidneys are enlarged, pale, uniformly covered with petechiae; histological lesions: brown-stained albumin in proximal convoluted tubules; necrotic epithelial lining cells mixed with proteinaceous substance such that the contents of the lumen form a dense homogeneous mass that is limited by the basement membrane and interstitial tissue.

POISONOUS PRINCIPLES: The toxins are unknown. Oaks contain large amounts of tannin (gallotannins), which has been implicated in poisonings. These substances are broken down into gallic acid and pyrogallol.

CONFUSED TAXA: Oaks are very common and not readily confused with other trees. One major forest type in Pennsylvania is the oak/hickory association. They are also planted for ornamental value.

SPECIES OF ANIMALS AFFECTED: Oaks are more a major problem on western rangeland than in Pennsylvania. Cattle, sheep, horses, and swine have been known to be poisoned. Human poisonings have not been reported.

TREATMENT: (11a)(b); (26)

OF INTEREST: Acorns and, to some extent buds, constitute a major source of wildlife food. Amerindians used acorns in their diet. White oak acorns were usually roasted and ground into a meal for use in "cakes." Books on edible wild plants often suggest eating acorns. Acorns from the white oak group apparently are palatable when cooked. The black oak/red oak group produces very bitter kernels. The white oak group can be differentiated from the red oaks by the presence of a scaly trunk. The tips and lobes of the leaves lacking bristly elongations, and the inside of the acorn smooth. Beech trees also are to be held suspect Beech nuts, the fruit of Fagus grandifolia Ehrh., are reported edible in America; European authors, however, claim they have poisonous properties. They should be avoided, at least in quantity.

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