Poisonous Plants of the Southern United States

moutainlaurel.jpg (41543 bytes)mountain laurel
Kalmia latifolia

Large, densely branched shrub or small tree up to 5 m tall. Leaves thick, leathery, evergreen, mostly alternate or in whorls of threes, elliptical, 8 to 15 cm long, 1.5 to 5 cm wide; margins entire and rolled in. Flowers white to pink, 2 to 3 cm in diameter, in large showy clusters. Found in all the southern states but less common in the coastal plain; most common on dry, rocky slopes and ridges and in open woods.

sheep laurel Kalmia angustifolia

Very similar to mountain laurel and also toxic. Shrub to 1.5 m tall. Usually a smaller plant than Kalmia latifolia with narrower and smaller leaves and smaller flowers that are more often pink than white. This species usually occupies wetter sites and mostly limited to mountainous areas of Georgia, the Carolinas and Virginia.


The resinoid, andromedotoxin, and a glucoside, arbutin, are the toxic principles responsible for symptoms. Sheep, goats and cattle are susceptible to poisoning if they consume the plant, especially the leaves.

There are recorded cases of toxicity in humans and monkeys. Most clinical cases of laurel toxicity are seen in the winter and early spring months. When other forage is not available, livestock may consume the toxic evergreen laurels.


Signs of toxicity occur usually within six hours after consuming the plants. Symptoms include incoordination, excessive salivation, vomiting, bloat, weakness, muscular spasms, coma and death. The animals are often found down, unable to stand, with their head weaving from side to side.


Animals should not be drenched or given medicine by mouth in severe cases since they may be unable to swallow due to weakness of the throat muscles. The administration of mineral oil or saline laxatives by stomach tube is suggested. In addition, intravenous electrolyte solutions may be used.


blackcherry.jpg (59922 bytes)black cherry
Prunus serotina

Medium sized tree with dark, smooth bark. Bruised twigs and leaves with a distinctive acrid taste and odor. Leaves alternate, deciduous, light green, elliptic to lanceolate, 6 to 12 cm long, 2 to 5.5 cm wide, crenate to crenate-serrate, two small glands near the juncture of blade and petiole. Flowers small, white, in terminal racemes 4 to 10 cm long. Ripe fruit black, shiny, juicy, .7 to 1 cm long. Distributed throughout the south, most common in fence rows, open woods and pastures.

choke cherry Prunus virginiana

Shrub with extensive rhizomes and thus often appearing in clumps. Leaves are smaller than P. serotina with smaller, sharper teeth and ripe fruit are dark red to purple. Uncommon except perhaps along streams in Tennessee or in moist places in Oklahoma and Texas.

cherry laurel Prunus caroliniana laurocerasus

Small to medium-sized tree, sometimes clipped to form dense hedges, 1 to 3 m tall. Leaves alternate, evergreen, dark green, shiny, elliptic to elliptic lanceolate, 5 to 10 cm long, 1.5 to 4 cm. wide; leaf margins variable, entire to serrate or denticulate. Flowers small, white, in axillary racemes 1.5 to 3 cm long. Ripe fruit dull black, only slightly fleshy. Georgia to Florida and west to Texas; most common in fence rows, low moist woods and maritime forest of coastal plain; often planted and escaping widely.


The toxic principle is hydrocyanic acid (also called prussic acid) which is created by enzymic action on the glucoside, amygdalin. It is present primarily in the leaves of trees that have fallen and are in a wilted condition. The bark and twigs are also toxic. Poisoning may occur in the spring, summer or fall.


Ruminants (cattle, sheep, goats) are most often affected, but single stomach animals, such as the horse, can also be affected.

Symptoms are difficult breathing, bloat, an anxious expression, moaning, staggering, recumbency and convulsions before death. Animals may die within one hour after consuming the leaves. The mucous membranes are bright red in color, as is the blood.


The intravenous injection of sodium nitrite and sodium thiosulfate is suggested. It must be given as early as possible. Treatments may need to be repeated within a few hours.

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