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Hickories (Carya spp.)

A variety of hickories occur in the Arboretum forests. Identifying a tree as a hickory is relatively easy - it has alternate, compound leaves (several leaf blades associated with each axillary bud) with 5 to 9 leaflets. Identifying the species of hickory, however, is more challenging and often requires determining characteristics of the leaves, hickory fruits (outer husks and nuts), the terminal buds, and the bark. Furthermore, there is considerable variation of these characteristics within a species and hybridization of species produces individuals with intermediate or mixed characteristics. Three of the more common hickories found at the Arboretum are described below.

Pignut Hickory Bark Pignut Hickory Fruit Pignut Hickory (C. glabra) leaves typically have 5 to 7 glabrous leaflets (i.e. without hairs). The pear-shaped to ovoid fruits are about 1 inch in diameter, with thin husks and nuts that are not ribbed. The bark is relatively tight, has vertically oriented ridges that are rounded, and may be flaky.

Mockernut Hickory Bark Mockernut Hickory Fruit Mockernut Hickory (C. tomentosa) has leaves with 7 to 9 leaflets that are pubescent on the undersides. The globular to oval fruits are about 1 1/4 inches in diameter, with thick husks and a 4-ribbed nut. The tight bark has flat to rounded, interlaced ridges.

Shagbark Hickory Bark A few Shagbark Hickories (C. ovata) are found along our trails. Their leaves usually have 5 essentially glabrous leaflets. The 1 1/2 inch diameter fruit has a thick, rounded husk that splits all the way to the base, and a nut ridged on 4 sides. The distinctive bark is broken into long, shaggy plates.

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University of Tennessee - Forest Resources AgResearch and Education Center
901 South Illinois Avenue, Oak Ridge, Tennessee 37830 · Telephone: 865-483-3571 · Email: UTforest@utk.edu