The leaves are alternate, 5–7.5 cm (2.0–3.0 in) long and 2–4 cm (0.79–1.57 in) wide, stiff, yellow green and dull matte to sub-shiny above (distinctly less glossy than the otherwise fairly similar European holly, Ilex aquifolium),[6] often pale yellow beneath; the edges are curved into several sharp, spike-like points, and a wedge-shaped base and acute apex; the midrib is prominent and depressed, the primary veins conspicuous; the petiole is short, stout, grooved, thickened at base, with a pair of minute stipules.

The leaves remain on the branches for two to three years, finally falling in the spring when pushed off by growing buds.

The corolla is white, with four petal-like lobes united at the base, obtuse, spreading, hypogynous, imbricate in bud.

This fruit (drupes) appear late in the season, and whether due to the need to ripen or being a food of last resort, often last until midwinter.

They are poisonous to dogs, cats, and humans, often causing diarrhea, vomiting, dehydration, and drowsiness if ingested.

[9] Cedar waxwings (Bombycilla cedrorum) will strip the trees of fruit if they are not already bare during their northward migration.

[11] The current world record American Holly tree is located in Rose Bud, White County, Arkansas.

It has four recognized subspecies/variations:[3] Due to its shade tolerance, Ilex opaca typically grows as an understory tree in moist forests of the east-central, southeastern, and south-central United States.

Songbirds including thrushes, mockingbirds, catbirds, bluebirds and thrashers, as well as some gamebirds and mammals frequently feed on the berries.

[4][8][15] The wood is very pale, tough, close-grained, takes a good polish, and is used for whip-handles, engraving blocks and also cabinet work.