Introduction

A popular landscape plant since the beginning of American history, this broad-leafed evergreen has served a variety of uses through the years. The American Indians used preserved holly berries as decorative buttons, which 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.

General Information

Scientific name: Ilex opaca

Pronunciation: EYE-lecks oh-PAY-kuh

Common name(s): 'Yellow Jacket' American holly

Family: Aquifoliaceae

USDA hardiness zones: 6A through 9B (Figure 2)

Origin: native to North America

Invasive potential: native cultivar

Uses: urban tolerant; bonsai; 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); highway median

Description

Height: 25 to 50 feet

Spread: 15 to 25 feet

Crown uniformity: symmetrical

Crown shape: pyramidal

Crown density: dense

Growth rate: slow

Texture: medium

Foliage

Leaf arrangement: alternate (Figure 3)

Leaf type: simple

Leaf margin: pectinate, entire, spiny

Leaf shape: elliptic (oval), lanceolate

Leaf venation: pinnate, brachidodrome

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

Flower

Flower color: green, white/cream/gray

Flower characteristics: not showy

Fruit

Fruit shape: round

Fruit length: less than 0.5 inch

Fruit covering: fleshy

Fruit color: orange

Fruit characteristics: attracts birds; showy; fruit/leaves not a litter problem

Trunk and Branches

Trunk/bark/branches: branches droop; not showy; typically one trunk; thorns

Pruning requirement: little required

Breakage: resistant

Current year twig color: green, brown

Current year twig thickness: medium

Wood specific gravity: 0.61

Culture

Light requirement: full sun, partial sun or partial shade, shade tolerant

Soil tolerances: sand; loam; clay; acidic; slightly alkaline; well-drained; occasionally wet

Drought tolerance: high

Aerosol salt tolerance: high

Other

Roots: not a problem

Winter interest: yes

Outstanding tree: no

Ozone sensitivity: unknown

Verticillium wilt susceptibility: resistant

Pest resistance: resistant to pests/diseases

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 yellow 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.

See the species for other cultivars.

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.