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Publication #ENH463

Ilex opaca: American Holly1

Edward F. Gilman and Dennis G. Watson2

Introduction

A popular landscape plant since the beginning of American history, this broad-leafed evergreen has served a variety of uses through the years (Fig. 1). The American Indians used preserved Holly berries as decorative buttons and were much sought after by other tribes who bartered for them. The wood has been used for making canes, scroll work and furniture, and has even been substituted for ebony in inlay work when stained black.

Figure 1. 

Middle-aged llex opaca: American Holly


Credit:

Ed Gilman


[Click thumbnail to enlarge.]

General Information

Scientific name: Ilex opaca

Pronunciation: EYE-lecks oh-PAY-kuh
Common name(s): American Holly
Family: Aquifoliaceae
USDA hardiness zones: 5B through 9 (Fig. 2)
Origin: native to North America
Invasive potential: little invasive potential
Uses: street without sidewalk; specimen; hedge; reclamation; screen; parking lot island 100-200 sq ft; parking lot island > 200 sq ft; tree lawn 3-4 feet wide; tree lawn 4-6 feet wide; tree lawn > 6 ft wide; sidewalk cutout (tree pit); urban tolerant; highway median; Bonsai
Availability: generally available in many areas within its hardiness range

Figure 2. 

Shaded area represents potential planting range.


[Click thumbnail to enlarge.]

Description

Height: 35 to 50 feet

Spread: 15 to 25 feet
Crown uniformity: symmetrical canopy with a regular (or smooth) outline, and individuals have more or less identical crown forms
Crown shape: pyramidal
Crown density: dense
Growth rate: slow
Texture: medium

Foliage

Leaf arrangement: alternate (Fig. 3)

Leaf type: simple
Leaf margin: pectinate, entire, spiny
Leaf shape: elliptic (oval), lanceolate
Leaf venation: banchidrome; pinnate
Leaf type and persistence: evergreen, broadleaf evergreen
Leaf blade length: less than 2 inches, 2 to 4 inches
Leaf color: green
Fall color: no color change
Fall characteristic: not showy

Figure 3. 

Foliage of American Holly.


[Click thumbnail to enlarge.]

Flower

Flower color: green, white

Flower characteristics: pleasant fragrance; inconspicuous and not showy

Fruit

Fruit shape: round

Fruit length: less than .5 inch
Fruit covering: fleshy
Fruit color: red
Fruit characteristics: attracts birds; no significant litter problem; persistent on the tree; showy

Trunk and Branches

Trunk/bark/branches: bark is thin and easily damaged from mechanical impact; droop as the tree grows, and will require pruning for vehicular or pedestrian clearance beneath the canopy; not particularly show; should be grown with a single leader; no thorns

Pruning requirement: needs little pruning to develop a strong structure
Breakage: resistant
Current year twig color: green, brown
Current year twig thickness: medium
Wood specific gravity: 0.61

Culture

Light requirement: tree grows in the shade; tree grows in full sun

Soil tolerances: sand; loam; clay; acidic; slightly alkaline; extended flooding; well-drained
Drought tolerance: high
Aerosol salt tolerance: high
Soil salt tolerance: moderate

Other

Roots: not a problem

Winter interest: tree has winter interest due to unusual form, nice persistent fruits, showy winter trunk, or winter flowers

Outstanding tree: not particularly outstanding

Ozone sensitivity: tolerant

Verticillium wilt susceptibility: not known to be susceptible

Pest resistance: long-term health usually not affected by pests

Use and Management

American Holly is a beautifully shaped tree, with a symmetrical, dense, wide pyramidal form. The spiny, dull green leaves are accented with clusters of red berries which persist throughout the fall and winter. Male and female flowers appear on separate trees and trees of both sexes must be located in the same neighborhood to ensure production of berries on the female plants. American Holly is ideal for use as a street or courtyard tree (with lower branches removed), framing tree, specimen, barrier planting or screen. Roots are shallow and finely branched, and rarely invasive due to their great number and relatively small diameter. This native tree is ideal for naturalizing on moist, slightly acid soils, and the fruit is very attractive to wildlife, serving as an excellent food source. A 35-foot-tall tree can be 20 feet wide in 40 years.

Growing well in full sun to partial shade, American Holly should be located on fertile, well-drained but moist, slightly acid soils below 6.5 pH. Berry production is highest in full sun on female trees. American Holly foliage thins during drought but insect and disease infestations are usually minimal.

Hundreds of cultivars of American Holly have been developed and hybridized over the years, providing variety of form, leaf characteristics, and fruit color. The following is a list of some available cultivars and hybrids: `Carolina #2' has dark green leaves and abundant fruit; `George E. Hart' has a narrow conical growth habit with small dark green leaves; `Hume No. 2' has compact, dark green foliage, and heavy fruit; `Croonenburg' has dark green, slightly glossy foliage and abundant fruit; `Howard' has dense, glossy green leaves with few spines, large fruit, and a more compact form; `Greenleaf' is softer in form than `Croonenburg', fast-growing, and responds well to shearing; `Jersey Knight', a male cultivar, is very hardy and has excellent foliage; `Jersey Princess', a female cultivar, has excellent form and shining dark green leaves; `Rotunda' has an upright growth habit, smooth, entire, glossy green leaves, and is profusely fruiting; `Ft. McCoy', `Dupre', `Lake City', `Savannah', and `Taber' all have quite spiny leaves. `Savannah' also has wavy curved foliage and dark, heavy fruit; `East Palatka', a female cultivar, is actually Ilex x attenuata , a cross of Ilex cassine x Ilex opaca , and has only a small spine at the leaf tip. Those with yellow berries include: `Xanthocarpa', `Canary', and `Morgan Gold'.

Those cultivars particularly adapted for the south include: `Amy' - female, abundant fruit; `Bountiful' - cone-shaped, compact, dark red fruit annually; `Calloway' - yellow fruit; `Miss Helen' - dark red, abundant fruit; `Slim Jim' - open, slender Holly with narrow leaves; `Steward's Cream Crown' - creamy, marginal venation; `Yellow Jacket' - cadmium orange fruit.

Propagation is by cuttings or grafting.

Pests

Holly leaf miner larvae mines out the leaf middle leaving yellow or brown trails.

Scales of various types may infest Holly.

Spider mites cause discoloration and speckling of Holly foliage.

Diseases

Tar spot may occasionally cause small yellow spots on the leaves in early summer. Eventually the spots turn reddish brown with narrow yellow borders. Leaves may not drop prematurely but the infected areas drop out leaving holes in the leaves. Gather up and destroy badly infected leaves.

Many different fungi cause leaf spots on Holly. Reduce the injury caused by leaf spots by keeping trees healthy. Dispose of diseased leaves.

Cankers caused by several different fungi lead to sunken areas on stems and plant dieback. Keep trees healthy and prune out infected branches.

Spine spot is small gray or yellow spots with purple margins and is caused by spines of one leaf puncturing an adjacent leaf.

Chlorosis symptoms are light green or yellowish leaves with darker green veins. This problem is often due to a high pH leading to iron deficiency. Use acidifying fertilizers and sulfur to bring down the pH. Sprays of iron chelate will green up plants.

In northern climates, Hollies sometimes scorch during the late winter due to rapid and wide temperature fluctuations. Shade plants during the winter to prevent the problem.

Purple blotches on the leaves are caused by some environmental factor such as nutrient deficiencies, drought, and winter injury.

Black root rot can be damaging.

Footnotes

1.

This document is ENH463, one of a series of the Environmental Horticulture Department, UF/IFAS Extension. Original publication date November 1993. Revised December 2006. Reviewed February 2014. Visit the EDIS webwite at http://edis.ifas.ufl.edu.

2.

Edward F. Gilman, professor, Environmental Horticulture Department; Dennis G. Watson, former associate professor, Agricultural Engineering Department, UF/IFAS Extension, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.