Plant of the Week: American Holly

The High Line's planting design is inspired by the self-seeded landscape that grew up between rail tracks after the trains stopped running in the 1980s. Today, the High Line includes more than 300 species of perennials, grasses, shrubs, and trees – each chosen for their hardiness, adaptability, diversity, and seasonal variation in color and texture. Some of the species that originally grew on the High Line's rail bed are reflected in the park landscape today.

This week we share one of our gardeners' current favorites with you.

Ilex opaca, the American holly, also referred to as the Christmas holly, joins the English, Chinese, and Japanese holly species in being one of the most well-known to professional and home gardeners alike. Hollies are well known for a reason; they are widely scattered around the world from temperate to tropical climates, throughout the Northern and Southern Hemispheres. The genus Ilex is native to every continent except Antarctica, collectively comprising well over 400 hundred individual species.

A large portion of hollies occur in nature as trees and shrubs, but there are a few exceptional species of Ilex that are climbers and epiphytes – a non-parasitic plant that derives its moisture and nutrients from the air and rain, and is found growing on other plants, such as trees. Most algae, moss, orchids and ferns are epiphytes.

North America alone has about thirty different native evergreen and deciduous species, including Ilex opaca. The American holly is a temperate species native to the eastern United States and found as far north as New England, extending west to Ohio and south to Texas and Florida. Such a diverse habitat reflects the hollies adaptability to various cultural conditions. Ideally, American holly enjoys moist, rich, acidic soils and prefers full sun. Growth, flowering, and fruiting capabilities will be minimal in low-light conditions. Ilex opaca is a broadleaf evergreen tree with a pyramidal growth habit that reaches heights of 30 – 50 feet.

Most people growing holly for the first time are surprised to learn that these plants are generally male and female, or dioecious. Dioecy, a word of Greek origin which translates to "two households," means that there are separate male and female organisms. In order for female hollies to bear fruit, there must be at least one male nearby to ensure pollination. The American holly has tiny green flowers in early summer that produce a pollen too heavy to become airborne. Insects, such as bees, flies, and beetles are necessary for cross-pollination.

The inconspicuous flowers mature into abundant red berries which persist throughout all of winter. In addition to being an important food source for native song birds and other wildlife, the berries are a striking ornamental feature and contrast beautifully with the spiny, dark green leaves. The winter months in particular are when the holly truly stands out amongst the bare landscape. Although the leaves are fleshy and waxy, they are susceptible to winter wind desiccation and fare better in well-protected areas away from direct wind.


You can see the American holly in the High Line's Chelsea Thicket, between West 20th Street and West 22nd Street.

Download our March bloom list.

Our horticultural team counts on members and friends like you to help keep the High Line beautiful and thriving. Join our community of supporters who play an essential role in the High Line's most important gardening projectsbecome a member of the High Line today!

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