Evergreen tree to 15 m or so tall but generally smaller in cultivation. Leaves mostly 6-10 cm long, 2-3.5 cm wide, oblong to elliptic, leathery, dull green above, margin with spiny teeth except on the uppermost branches of older trees. Flower parts 4. Fruits spherical, 0.5-1.5 cm wide, mostly red, rarely yellow or orange.
The name opaca means opaque or dull and was presumably used to draw attention to the contrast in leaf surfaces of this species and the glossy ones of the similar European I. aquifolium. There are many cultivars of this holly available in America but not yet in Australia.
E and C USA.
Source: (2002). Aquifoliaceae. In: . Horticultural Flora of South-eastern Australia. Volume 3. Flowering plants. Dicotyledons. Part 2. The identification of garden and cultivated plants. University of New South Wales Press.