Guide to Hollies (Ilex spp.)

 In New Jersey there are two common hollies growing wild: American holly (I. opaca) and common winterberry (I.verticillata). There are two other wild hollies: smooth winterberry (I. laevigata) and inkberry (I. glabra), an escaped holly: Japanese holly (I. crenata), and garden, hybrid hollies (Ilex sp.)

Hollies with classic, prickly leaves are either American or hybrid. Generally non-American garden hollies do not escape, but they persist for a long time and so can appear to be wild. American holly will have more than two prickles on each side of the leaf and the leaves will not be particularly twisted. 

Japanese Holly is mostly a planted shrub but does sometimes escape and also persists in now-wild locations. It is more likely to be confused with box (Buxus sp.) than with any other holly, but it always has alternate leaves (box is opposite) and tiny teeth on the outer half of the leaf (box is entire). The leaves are tiny and evergreen, as in box. 

Inkberry is mostly found in very dry soil of the Pine Barrens and ridgetops. It is also often planted in landscaping. It has more elongated, evergreen leaves usually with only a few slight teeth at the tip, and black fruit. The leaves are always at least three times as long as wide. 

Winterberries are difficult to separate. Common is vastly more common in NJ than smooth, which may be confined to the coastal plain. Both have large deciduous leaves with fine teeth all along the edge and red fruit. 

Common winterberry has: branches roughly all the same length. Twigs sometimes hairy. Leaves mostly less than twice as long as wide. Leaves mostly widest above the middle. Leaves sometimes hairy below or even above. Leaves rugose (quilted looking). Leaves with most veins below very prominent. Leaves generally with sharp teeth. Fruit usually clustered in a way that looks whorled around stem. Fruit generally under 7mm. Fruit with stems clearly shorter than the width of the fruit.

Smooth winterberry has: some branches much longer and some much shorter than others. Twigs never hairy. Leaves mostly two to three times as long as wide. Leaves usualy widest at the middle. Leaves not quilted (rugose). Teeth sometimes appressed and sometimes rounded. Leaves usually smooth or with some hair on the veins below. Leaves with only a few veins prominent on the underside. Fruit generally singly in the leaf axils. Fruit generally over 7mm. Fruit stems generally about equal to the width of the fruit.