The Poisonous Effects of the American Holly Plant

Identification

• While not as spiny or glossy as the typically holiday-associated English holly (Ilex aquifolium), which is winter hardy to U.S. Department of Agriculture plant hardiness zones 7 through 9, the American holly is also evergreen with classic spiny leaves. American holly is winter hardy in USDA zones 5 through 9, and although it does not produce showy flowers, it does have bright red or yellow berries. It is a tolerant plant that grows in a range of soil types as long as they are well drained, in sun or partial shade, and with a medium amount of water.

Toxins

• The toxins of the holly plant are concentrated in its berries and are not present in wood, bark, stems or leaves. The compounds responsible for the poisonous effects are illicin and triterpenoids, and possibly saponic glycosides. When eaten in large enough quantities, berries may cause nausea, vomiting and diarrhea as well as prolonged periods of drowsiness. Toxicity is low, so you do not need to worry about berries causing death, but even a small amount of berries -- more than 3 -- may cause serious stomach discomfort.

Precautions

• Even though berries of the American holly are only toxic if eaten in large quantities, children or pets might make themselves sick eating them. Keep animals away from the tree or observe them when they are near a holly tree whose berries have dropped in late winter or early spring. Warn children not to eat the berries of the holly tree or any berry not given to them by an adult. If you do not care about berries, you can plant a male species that does not produce them.

Garden Uses

• Hollies are a relatively short tree, only reaching between 15 and 30 feet in height, and are therefore good as a small landscape specimen. They also do well planted in groups as a hedge or screen. Their flowers attract bees when in bloom and provide nectar for making honey. Evergreen leaves and persistent berries add color in wintertime, and the foliage can be used for holiday decoration.