American Holly | Glen Arboretum

American holly

Ilex opaca Aiton

Description

American holly (holly family, Aquifoliaceae) is an evergreen tree with broad leaves and brilliant red, ⅓ inch diameter² berries that ripen in October and last into winter³. It can grow to be up to 40-50 feet tall and 18-40 feet wide³. The US Champion American holly is in Arkansas and measures 64 feet in height and 58 inches in diameter spring⁵. Its white flowers are dioecious (male flowers and female flowers grow on separate plants),² and mature in late spring⁴. Its leaves are thick, tough, simple, alternate⁴, 2-4 inches long², spiny and dark green to yellowish-green³. Its bark is grayish-white and sometimes white⁴. American holly trees grow in a pyramidal shape². American holly berries are toxic to cats, dogs, horses, and humans, and can cause nausea, vomiting, diarrhea, and depression³.

American holly fruit and leaves. Wikimedia⁹

Pyramidal shape of tree. Wikimedia¹⁰

Distribution

American holly trees are found from Massachusetts to Florida, Texas, and Missouri³. In the wild they grow near swamps and rivers⁴, in pine forests², and in mixed deciduous forests⁴. They are often found in the understories of forests⁶. American holly trees grow best in moist, loose, acidic soil, in full sun⁷; and they tolerate cold weather quite well³. American holly trees need about 3-6 feet of space per plant and are found from the 5A to 9B USDA hardiness zones⁴. American holly trees often grow alongside longleaf pine, sweetgum, red maple, yellow poplar, and black tupelo trees⁶. In Maryland, American holly trees are mostly found in the Coastal Plain and Piedmont regions, and are generally not present in the western area of the state⁸.

{Native range of Ilex opaca}

Native distribution of American holly. USDA²

Wildlife importance

Over 18 species of birds, including wild turkeys and mourning doves eat American holly berries. Squirrels and other small animals, and occasionally cattle and deer also consume the plant⁶. The endangered red-cockaded woodpecker makes its nest in American holly trees. Planting American holly can help to restore forests damaged by ocean spray⁶ . It sometimes competes with pines and hardwoods for sunlight, water, and nutrients⁶. American holly provides nectar to butterflies and other insects during the spring/summer and shelter for animals during the winter⁴.

Economic Importance

American holly wood can be used to make furniture, canes, veneer, cabinets, scientific instruments⁶ knife handles and (since it holds dye very well) black piano keys and violin pegs/fingerboards³^,6. American holly can be planted for Christmas or year-round decoration, in yards, streets, parks, and hedges⁶.

Threats

The leaf miner and scale insects are the American holly’s biggest predators, but it’s also afflicted by many other insects and conditions, such as powdery mildew, beetles, and leaf scorch³. Aggressive harvesting of holly berries by humans, flooding⁴ and fire are also threats to the American holly⁶.

Interesting facts

American holly trees only produce either male or female flowers, so in order to produce berries, you must plant one male holly tree for every three female ones³.
Superstitions about American holly include that holly flowers could be used to turn water into ice and that planting holly trees near buildings would ward against witchcraft and lightning strikes³.
Some Native Americans would make and trade buttons made of American holly berries³.
In the early 1900s, holly decorations were so popular at Christmastime that people would cut down and steal the trees from other people’s property⁷. Both Maryland and Delaware outlawed the sale of fresh holly in an attempt to foil these holiday crimes⁷.
Some varieties of American holly produce yellow berries⁷. On average, a pound of American holly berries contains 28, 430 seeds².
The Romans would give European holly as gifts to one another during the Festival of Saturn (a winter solstice celebration during late December) for good luck and protection⁷.
Among European Christians, holly was used during Christmastime since its spiky thorns and red berries symbolized Jesus’s crown of thorns and blood⁷.

References

Contributed by T. Zurek

Towson University Glen Arboretum