840 Ilex glabraCommon Names: gallberry, inkberry, bitter gallberry, evergreen winterberry, inkberry holly, Appalachian tea Family: Aquifoliaceae (holly Family)
Gallberry is a slow growing medium sized evergreen shrub with fine textured foliage. It has an upright rounded habit, developing multiple trunks and spreading and becoming open and leggy as it grows to a mature height of 4-8 ft (1.2-2.4 m). The smooth dark gray brown to greenish black stems arise from heavy tuberous rhizomes. They branch into flexible light green twigs with alternate narrowly oval leaves that are shiny and dark green on top and duller and lighter on the underside. The leaves are 1-2 in (2.5-5.1 m) long and 1/3-1/2 in (0.8-1.3 cm) wide and have smooth edges except near the tip, where there are several teeth. Tiny creamy white flowers appear half-hidden in the foliage in late spring. On male plants the flowers are borne in clusters, whereas female plants bear single flowers. They are followed by 1/3 in (0.8 cm) green berries that turn black as they ripen in the early fall. These fruits hang on the bushes all winter, but are too sparse to be of ornamental value. Sometimes the foliage develops a plum colored cast in the winter. The horticultural varieties of I. glabra are all more dense and compact than the species and less inclined to spread by suckering. They include 'Compacta' - a broad, slow growing female form that reaches 5 ft (1.5 m) tall and bears lots of berries, but gets leggy at a relatively young age; 'Nordic' - an especially cold tolerant male variety that grows to 4 ft (1.2 m) tall and retains a tighter growth form; 'Chamzin' - a very hardy compact cultivar that reaches a height and spread of 4 ft (1.2 m); 'Densa' - a form that does not lose lower foliage as it ages; 'Viridis' - a fast grower with a broad upright form; and 'Green Magic' - a dark-leaved slow grower that retains its lower branches. 'Ivory Queen' and 'Leucocarpa' produce white fruits.
Gallberry, Ilex glabra, is native to the pine flatwoods of the eastern and south-central United States.
CultureGallberry grows on relatively infertile sandy to peaty soils with low pH. It will not perform satisfactorily on alkaline soils. If the foliage begins to look chlorotic, treat with a fertilizer containing nitrogen, iron, and micronutrients. Gallberry grows less than 12 in (30.5 cm) per year, so it does not need frequent trimming, although it tolerates shearing and benefits from pruning to enhance density. It can be cut back severely for rejuvenation when it begins to get leggy. This species comes from fire maintained habitats and is adapted to survive fire by resprouting from root crowns and rhizomes. Repeated annual summer burning will weaken the shrubs and eventually kill many of them, however. Gallberry has few pest problems other than occasional leaf spot. It may be afflicted by spider mites in especially dry situations or show foliage burn on harsh exposed sites. Light: Gallberry can be grown in full sun or partial or light shade Moisture: Gallberry tolerates drought well, but prefers sites that are moist to wet most of the time. Hardiness: USDA Zones 5 - 10. Gallberry foliage is subject to freeze burn when the temperature drops below around -15ºF (-26ºC). The branches are prone to breakage under a heavy ice load. Propagation: Gallberry may be grown from seed, but it is a slow process. The pulp must first be removed from the fruit. The clean seeds should then be planted 1/8 in (0.3 cm) deep in rich sandy loam and kept moist. It may take 2-3 years for them to germinate. Then the slow growing seedlings should be potted up and cared for in half-shade for 2-3 years before they are planted out. Gallberry readily sprouts from root crowns and rhizomes and may be propagated from stem cuttings, root cuttings, or suckers. Taking mature cuttings in winter and rooting them under glass is recommended. Roots about 3/8 in (1 cm) in diameter are best for root cuttings. They should be planted partially exposed. Another propagation alternative is to prune back the top growth, then root prune a shrub on one side, wait a year, and then dig up and replant the roots.
Gallberry may be used in foundation shrubbery, mass plantings, or informal hedges and borders, as well as in naturalistic landscapes, ecological restoration projects, or habitat enhancement plantings. Bobwhite, turkeys, bluebirds, brown thrashers, hermit thrushes, and other birds frequently eat gallberry fruits and raccoons, coyotes, and opossums feed on them when other food is scarce. Marsh rabbits and white tailed deer browse on the leaves and black bears even eat them on occasion. Gallberry is also an important honey plant. Bees feeding on it produce a highly flavorful amber colored honey. Gallberry is not particularly invasive, but it may become a nuisance by forming larger clumps than desired and spreading into adjacent plantings.
Gallberry is a useful native American species to substitute for less vigorous landscaping shrubs in creating masses of year round green. In northern climates, gallberry can be substituted for Japanese holly (Ilex crenata), which is much less cold tolerant. It also makes a good replacement for boxwood where a larger and faster growing shrub is desired.
Linda Conway Duever 10/29/00; updated 2/13/04