Inkberry

(Aquifoliaceae - Holly Family)

Form

• medium-sized evergreen foliage shrub (cultivars are smaller)
• species form matures at about 8' tall by 8' wide, forming colonies with time
• upright oval growth habit, becoming spreading, suckering, and leggy with age
• slow growth rate (except for rapid basal suckers)

Culture

• full sun to full shade
• prefers moist to wet, acidic soils in partial sun to partial shade, but is somewhat adaptable to soils of various pHs and to dry soils
• propagated by rooted stem cuttings, separation of basal suckers from parent plants, or by seeds
• Holly Family, with only leaf spot as an occasional cosmetic disease problem, and virtually no pest problems
• abundantly available, in container or ball and burlap form
• becoming leggy (absence of foliage and new stem growth from the basal branches), open, and spreading with age, and also suckering to form colonies
• as a general rule, broadleaf evergreens should not be placed in South- or West-facing exposures to avoid Winter foliage burn; although Inkberry performs better than most under these adverse conditions, it will start to foliage burn at about -15 degrees Fahrenheit (-26 degrees Celsius)
• fertilize with a micronutrient-containing fertilizer if the foliage becomes chlorotic (chartreuse to light green, instead of dark green, from iron and nitrogen deficiency in alkaline pH soils)
• tolerates light to moderate shearing very well, to promote compactness

Foliage

• evergreen, alternate, narrow obovate, and shiny dark green (lighter green in alkaline soils, especially in Winter)
• margins are entire except for a few sparse serrations near the leaf apex

Flowers

• miniature cream-colored male and female flowers occur in June on separate plants (dioecious), hidden among the previous year's evergreen foliage and ornamentally insignificant

Fruits

• if a male pollinator is present, sparse green berries on female shrubs mature to black in September (hence the common name of Inkberry), and persist until the following Spring
• not ornamentally significant due to their paucity and poor color contrast against the dark evergreen foliage; also, many cultivars are male clones

Twigs

• slender and light green, flexible and bending under a light snow load, but somewhat brittle and prone to breakage under an ice load or heavy wet-snow load

Trunk

• with maturity, the several basal trunks are quite leggy, smooth, and light gray

USAGE

Function

• shrub for foundations, borders, group plantings, mass plantings, formal or informal hedges, backgrounds, specimens, or naturalized areas

Texture

• fine texture
• thick density until maturity, when it may become average to open in its density (unless it has been periodically sheared)

Assets

• attractive broadleaf evergreen foliage
• takes well to shearing
• wet site tolerant
• full sun to full shade adaptable
• much more cold hardy than Japanese Holly (Ilex crenata), with which it is sometimes confused and interchangeably used in Southern climates
• larger and more rapidly growing alternative to modern Boxwood hybrids

Liabilities

• legginess with age (absence of foliage on lower stems)
• prone to stem breakage under heavy ice or snow loads
• occasional Winter foliage burn in its Northernmost range
• species form is suckering with age, forming a broad colony beyond its original boundary

Habitat

• zones 4 to 9
• native to the Eastern United States

SELECTIONS

Alternates

• shrubs with broadleaf evergreen foliage (Buxus hybrids, Ilex x meserveae, Ilex opaca, Mahonia aquifolium, etc.)
• shrubs tolerant of wet sites (Cornus sericea, Hamamelis vernalis, Lindera benzoin, Salix purpurea, etc.)

Variants

• all cultivars are more compact, less leggy, less open in the canopy, and much less suckering that the species form; the most common cultivars include:
• Ilex glabra 'Compacta' - female selection, to 5' tall, but still quite leggy even at a relatively young age
• Ilex glabra 'Nordic' - male selection, to 4' tall, more dense and compact growth, not as leggy, with zone 3 cold hardiness
• Ilex glabra 'Shamrock' - still more dense and slower growing, to 2' tall, with smaller foliage and the least amount of legginess; probably the best cultivar overall

NOTES

Translation

• Ilex comes from the name of a species of Oak native to the Mediterranean.
• glabra translates as "smooth", referring to the leaf surface.

Purpose

• Inkberry is a broadleaf evergreen shrub that is tolerant of continually moist to wet sites, with good broadleaf evergreen character and cultivars that are much more compact than the species form.

Summary

• Ilex glabra is one of the very few evergreen shrubs (broadleaf or narrowleaf) to thrive in wet sites, noted for its evergreen foliage and upright, spreading, and suckering shrub growth habit when in species form, but the compact cultivars serve as an alternative to Boxwood (Buxus) in situations where a refined but taller and faster growing broadleaf evergreen is needed, and an alternative to Japanese Holly (Ilex crenata) where a more cold-hardy broadleaf evergreen is needed.