Since that time, American holly, also known as white holly or Christmas holly, has been one of the most popular and valuable trees found in the Eastern United States. It's grown for the foliage and berries, used for Christmas decorating, and valued as an ornamental.
I first became familiar with this handsome tree at a yard sale not far from my house. A beautiful specimen replete with berries was growing in the yard there and I was curious. The owner didn't have a lot of information about the tree so I began researching to learn more.
Much like the southern pine tree, the American holly (Ilex opaca) is found mainly in USDA zones 5-9 in areas of the humid Southeast having an annual rainfall of 40-65 inches. The growing season varies from around 150 days in the Appalachian Mountains to nearly year around in central Florida.
American holly is the hardiest of all known broadleaf evergreens. Blooms are produced on the current season's growth beginning in April in the southern growth range and June in the north. Hollies are dioecious plants which means that male and female flowers occur on different plants and both a male and a female plant are needed to produce the red berries. Pollination is accomplished by insects including bees, wasps, ants, yellowjackets, and nocturnal moths. The fruit, commonly called berries, is technically a four-seeded drupe known as a pyrene.
Holly is quite shade tolerant and can survive in the understory of most forest canopies, but growth may be slowed and flowering and fruiting reduced in heavy shade. In some mesic pine hardwood forests in east Texas, Amercan holly is the most abundant understory tree found. The tree's slow growth allows faster-growing species of the same age to easily overtop it. Root competition and shade in natural stands may reduce average height compared to specimens growing in full sun. Medium shade can reduce crown size by one-third and heavy shade by more than one-half.
Damage done to holly trees is due mainly to indiscriminate harvesting of the berried foliage for Christmas decorating. Many trees are left mutilated and subsequently die. Because they grow in proximity to pine trees, fire becomes another enemy of the American holly. Most commercial pine timberland is burned often enough to eliminate holly seedlings. Burning where hollies grow in the mid-story can seriously damage the bark and kill the trees. Annual fires in one southern pine forest reduced the number of fruit-producing holly trees by 95%.
The thick evergreen leaves remain on the trees until spring of their third year. These leaves can become hosts to numerous foliage diseases and insects. Not many of these threaten the health of the trees, but they may greatly reduce the esthetic and commercial value of the foliage.
Some 30 species of insects are known to attack holly, however only a few are serious pests. Among these are the southern red mite, the native holly leafminer, holly midge and several species of scale insects. Damage from strong winds can cause spines of mature leaves to puncture young leaves thus making the foliage less valuable for decoration. Although very hardy, in northern portions of the tree's range cold can kill many twigs and branches. Holly is more resistant to damage from salt spray than many woody species in the maritime forests of New England which enables these trees to dominate coastal stands. However, hollies are intolerant of flooding and often die if flooded for several weeks at a time.
Birds consume the majority of holly berries. Deer, squirrels, and other small mammals also eat them. Cattle sometimes graze on the foliage. At least 18 species of birds including songbirds, mourning doves, wild turkeys, and bobwhites are known to eat the fruit. Most important in seed dispersal are large winter-migrating flocks of small birds such as the cedar waxwing and American goldfinch. Bird-watchers have recorded the complete stripping of all berries from a 35 ft. tall holly in less than 30 seconds by a flock of cedar waxwings.
The American holly is not considered poisonous to man or animals. The wood is hard and tough but lacks strength. Attractive foliage is the tree's principal value as a commercial tree, ornamental specimen, and Christmas decoration. Development of commercial holly orchards and educating landowners about the value of holly foliage and how to harvest it have reduced exploitation of wild trees.
English and American holly plants are the best known types of Ilex probably due to their large size, striking foliage, and long association with the Christmas season. Some varieties of English holly plants grow quite tall. The shorter Ilex aquifolium 'Ferox Argentea' reaches a moderate height of 15 feet and spreads 8-10 feet. It grows in zones 6-9. The pyramid-shaped American holly has spines on its foliage and blooms in May or June. Cultivars include: 'Jersey Princess' (a female), 'Jersey Knight' (male pollinator), as well as 'Canary' which sports yellow berries.
If you have an old holly plant you'd like to rejuvenate, trim back branches by 1/2 to 3/4 toward the end of winter.
(Credits: http://www.uky.edu/hort/American-Holly; https://www.thespruce.com/christmas-holly-history-2131214; https://www.na.fs.fed.us/spfo/pubs/silvics_manual/volume_2/ilex/opaca.htm; https://www.arborday.org/trees/treeguide/treedetail.cfm?itemID=1071; photos, top to bottom: https://louisvillewaterfront.com; [email protected]; Nicholas from Pennsylvania, USA (Evergreen) [CC BY 2.0 (http://creativecommons.org]; By Famartin (Own work) [CC BY-SA 4.0 (https://creativecommons.org; Plantfiles)