Ilex glabra is a slow-growing, upright-rounded, stoloniferous, broadleaf evergreen shrub. Ilex glabra ‘Shamrock’ was cultivated to be shorter than the straight species (which can grow 5-8 ft.) and suckers less than the straight species.
Leathery, glossy, dark green leaves have smooth margins, or edges. I. glabra differs from all other evergreen hollies by lacking spines on the leaves and only having teeth toward the tip of the leaves. Leaves usually remain attractive in winter unless temperatures dip well below zero.
Inconspicuous greenish white flowers appear along the stems. If fertilized, female flowers are followed by pea-sized, jet black, berry-like drupes which mature in early fall.
Inkberries are dioecious, meaning there are separate male and female plants. Female plants need a male plant to produce berries. Named cultivars of hollies (like “Shamrock”) are one sex, and all cultivars of I. glabra are female. The only male plant is the straight species, which I have been looking for and cannot find. I will keep looking for you! The suggested ration for males to females is 1:4, with the males planted within 50 feet of the females. According to the University of Maryland Extension, “The Holly Society of America noted in 2020 that some inkberries might have self-fertile flowers, or they may be pollinated by other Ilex species, such as Ilex crenata. This may account for berry production without a male inkberry.”
Prefers rich, consistently moist, acidic soils in full sun but has good shade tolerance. This species is noted for its ability to perform well in wet sites. Avoid neutral to alkaline soils. Prune to shape in early spring just before new growth begins if desires, but pruning is not necessary.
Height: 3-4 ft.
Spread: 3-4 ft.
Bloom time: May to June
Sun: full sun to part shade
Water: medium to wet
According to Rutgers University, Ilex glabra. are “seldom severely damaged” by deer.
photo credit: David J. Stang