Scientific name: Ilex opaca
American holly normally grows to heights of 15 to 30 feet tall, but records indicate mature heights of up to 100 feet. On the poor soils of coastal beaches, this holly may never exceed shrub size. The attractive evergreen foliage and bright red fruit of this small tree make it a very popular for landscaping. The same attributes that allow this tree to be a desirable ornamental make it one of the most sought after greens for Christmas decoration.
American holly normally grows to heights of 15 to 30 feet tall, but records indicate mature heights of up to 100 feet. On the poor soils of coastal beaches, this holly may never exceed shrub size.
The attractive evergreen foliage and bright red fruit of this small tree make it a very popular for landscaping. The same attributes that allow this tree to be a desirable ornamental make it one of the most sought after greens for Christmas decoration.
Did You Know?
You must have both a male and female plant to have berries, or at least have the opposite sex growing wild somewhere nearby. The male must be the same holly species as the female and bloom at the same time.
Many kinds of songbirds, gamebirds, and mammals eat the bitter berries of this and other hollies, but the fruits are poisonous to humans.
American holly grows from Massachusetts to Florida, west to Texas and Missouri, and is adapted to a wide range of site conditions. It grows best on well drained, sandy soils, but will tolerate those which are somewhat poorly drained. This small tree has good shade tolerance, but does well in direct sun. Although this species is often found growing on coastal sand dunes, it is not very salt spray tolerant.
The evergreen foliage is stiff and leathery in texture, with large, remotely spined teeth. The leaves are arranged alternately. They are 2 to 4 inches long, satin green and smooth above, and yellowish-green below.
Bright red, rarely orange or yellow, globular fruit mature from September to October, but may be retained on the plant into the following spring. The berry-like fruit is about 1/3 inch in diameter, and contains 4 to 9 small nutlets. There are an average of 28,430 seeds per pound.
Small, axillary, greenish-white flowers bloom from April to June. Like most others in the holly genus, American holly is dioecious. Pistillate flowers emerge in small clusters from one plant, while staminate flower clusters develop on another. Newly established plants will not flower for 4 to 7 years; prior to flowering there is no practical means of determining the gender of a plant.
The firm bright red berries are consumed by white-tail deer and 18 species of birds. The dense foliage also provides cover and nesting habitat for various songbirds.
More on Trees and Shrubs in Lewisboro
Lewisboro was once entirely forested except for patches of open field caused by fire and wetlands and ponds which were expanded by beaver dams. Although it is hard to believe, by 1800 most of Lewisboro’s forests had been cut down and replaced by farms. In 1820 so many trees had been cleared that there was no shade anywhere along the route from Boston to New York. But by the mid-1800’s farming here became uneconomical and as farms were abandoned, the forests began to re-grow. Today, 70% of New York is once again forest, what some call ‘the great environmental story of the United States’. These new forests provide us with beauty and recreation, clean air and water, flood control, erosion prevention, carbon sequestration, cooler temperatures and habitat for other plants, insects, birds and other wildlife.
 Cronon, William. Changes in the Land. Macmillan, 1983.
 An Explosion of Green. B. Mckibben. Atlantic Monthly 275 (April 1995): 61-83.