Oregon Holly Ilex aquifolium

English holly is a large, ornamental, flowering, evergreen tree or shrub in the Aquifoliaceae or holly family. The plant is the traditional Christmas holly in Europe and is used for decoration. This slow-growing tree can reach 30 to 50 feet tall and 15 to 25 feet wide. It can be allowed to grow to its full height or pruned and trained as a 10 or 15-foot hedge. It has an erect, pyramidal habit, and is densely branched. The leaves are leathery, glossy, dark green, and have spiny teeth. Clusters of small fragrant white flowers appear in the spring. Plants in this species are dioecious or have separate male and female plants. The female plant requires a male pollinator to produce fruit. If the flowers are pollinated, reddish drupes will ripen in the late summer to fall. 

The English holly is native to Europe, North Africa, and Western Asia. It is often found in well-drained soils in scrub, hedges, and woodland where it is often the dominant under-story shrub. In the United States, the plant thrives and has become naturalized in the Pacific Northwest. It is listed on the invasive plant list in Oregon, California, and Alaska. It is also invasive in Redwood National Park and Yosemite National Park.

The genus name, Ilex, comes from the Latin name, Quercus ilex, for holm oak, and refers to the foliage similarities. The specific epithet, aquifolium, comes from the Latin word acus, meaning needle, and folium, meaning leaf.

This plant prefers full to partial sun and protection from the cold winter winds. It dislikes hot and humid summers and typically does not perform well in the southern United States.  It performs best in moist, well-drained soils, and is intolerant to poorly drained soils. It can grow in heavy clay and nutritionally poor or very acidic soils. Prune in the winter as needed to maintain its shape. The plant is pollinated by bees, and the birds are attracted to its fruits.

The English holly has over 200 cultivars. They are often grouped as non-variegated or variegated. The variegated groups have leaves with whitish margins or yellowish margins. Some have blotches or spots.

The ornamental English holly is effective as a specimen plant, grouped as a tall hedge or foundation planting. The foliage and fruit provide winter interest. It dislikes cold winters and is difficult to grow in the lower Midwest and Southern United States. In the south, sometimes the English holly is grafted to the Nellie R. Stevens Holly, to improve success.

Seasons of Interest:

Bloom:  Spring     Foliage:  Year-round        Fruits:  Late Summer, Fall, and Winter

Quick ID Hints:  

• erect, dense, pyramidal evergreen tree or shrub
• smooth, gray to black bark
• alternate, simple, elliptic, spiny, dark green, leathery, glossy, evergreen leaves
• clusters of small white fragrant flowers in the spring
• if female flowers pollinated, small red drupes appear in late summer to winter

Insects, Diseases, and Other Plant Problems: The English holly has no serious insect pests or diseases. If the tree or shrub is grown in excessively wet conditions, it may develop root rot, anthracnose, tar spot, leaf blight, or cankers. 

VIDEO created by Ryan Contreras for “Landscape Plant Materials I:  Deciduous Hardwoods and Conifers or Landscape Plant Materials II:  Spring Flowering Trees and Shrubs” a plant identification course offered by the Department of Horticulture at Oregon State University