Across the world there are over 400 different species of hollies, according to the American Horticultural Society's "A-Z Encyclopedia of Garden Plants." They take the form of trees, shrubs and rambling climbers. Many Americans, Asians and Europeans are familiar with the autumn-ripening fruits produced on hollies that range in color from red to black, and occasionally white, orange or yellow. Generally speaking, hollies prosper in moist, acidic soils that are fertile and grow in full sun to partial shade conditions that mimic the woodland habitats from where most originate.
Holly plants are found growing naturally in woodlands in temperate, subtropical and tropical areas around the world. According to Kirsten Albrecht Llamas, author of "Tropical Flowering Plants," hollies native to temperate regions are common garden plants, while those native to tropical regions are often overlooked since their dark green leaves and fruits are overshadowed visually by other more ornate plants.
Hollies belong to their own family, Aquifoliaceae, and are assigned to the botanical genus Ilex. The genus is further divided into three subgenera: Byronia, Prinos and Ilex. Subgenus Byronia includes one species of evergreen holly native to China, Prinos includes all deciduous hollies, and all other evergreen holly plants are lumped into the subgenus Ilex (which is further differentiated into six sections).
From a horticultural perspective, hollies are loosely discussed based on their leaf types (deciduous or evergreen), plant form (tree or shrub) and berry color. Many hybrids of hollies have been developed and selected by breeders for more useful features such as mature height, leaf coloration, or tolerance to cold or different soils.
Holly plants are dioecious--meaning the different gendered flowers occur on separate plants. Thus, a holly is referred to as "male" or "female"; only female plants produce and display the colorful fruits called berries. Most often, leaves of hollies are simple ovals with tiny or large teeth or spines. Deciduous hollies' leaves are thinner and papery in texture, while evergreen leaves are more leathery and glossy in texture and bear the largest spiny teeth. Usually the leaves are arranged in an alternating arrangement on branches. Holly flowers are tiny and a shade of white or cream, pollinated by insects. Hollies native to temperate regions bloom in early to late spring with fruits ripe by late summer, while those native to tropical areas bloom and fruit intermittently year round.
With a huge number of different species (and even more garden hybrids), holly plants have a wide variety of uses. Tree-sized holly plants can provide a scented, fine-grained wood that splits easily and burns at a hot temperature. These trees also act as shade or windbreaks and often are used to provide holiday decoration, both evergreen leaf and berry. Deciduous hollies are used primarily for ornamental use in gardens, since their copious fruit production is not masked by foliage in winter. They, too, are prized as Christmas and other winter holiday decorations in wreaths, garlands and bouquets. Holly fruits also are eaten by songbirds in fall and winter.
The following is a list of a few holly plants and their scientific species names:
English holly (Ilex aquifolium)
Dahoon holly (Ilex cassine)
Chinese holly (Ilex cornuta)
Japanese holly (Ilex crenata)
Possumhaw (Ilex decidua)
Himalayan holly (Ilex dipyrena)
Blue holly (Ilex x meserveae)
American holly (Ilex opaca)
Mate (Ilex paraguariensis)
Longstalk holly (Ilex pedunculosa)
Japanese winterberry (Ilex serrata)
Puerto Rican holly (Ilex sintenisii)
Winterberry (Ilex verticillata)
Yaupon holly (Ilex vomitoria)