Hickories (Carya)

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The North American species of hickory (Carya) are restricted to the Eastern Deciduous Forest. One species is found in the Mexican Highlands and two others in Asia. Although it is always difficult to make generalizations about a genus of trees, most hickories occur in drier areas of the Eastern Deciduous Forest, often with species of oak.

The hickories are characterized by compound leaves arranged alternately along the stem. A compound leaf consists not of a single leaf blade but of a number of leaflets arranged along the leaf stem. The leaf on the right in the drawing on the left is a single leaf composed of the leaf stem and five leaflets. These compound leaves are arranged alternately on the stem; specifically they alternative from one side of the stem to the other and are not opposite each other. The number of leaflets per leaf ranges between 5 and 13 depending on the species and the individual tree. Hickories have large nuts with an outer wooden husk covering an inner woody, shelled nut as in a pecan or walnut. The outer husk splits open on maturity. Pecan is a hickory of the genus Carya. By the time you buy them in the store, of course, the outer husk has been removed.

Hickories might be confused with ashes (Fraxinus) or Boxelder (Acer negundo). Both the ashes and Boxelder have compound leaves, but the leaves are arranged opposite each other on the stem, not alternate as in the hickories. The hickories are close relatives of the walnuts (Juglans) and both are in the family Juglandaceae. Walnuts usually have more leaflets per leaf than the hickories (greater than 13). The husk of the nut is fleshy, not woody, and does not split open when mature. The husks of hickories do split open when mature. Two important walnut species occur in the Eastern Deciduous Forest, Black Walnut (Juglans nigra) and Butternut (Juglans cinerea).

The hickory species illustrated on the left is Shagbark Hickory (Carya ovata). Shagbark Hickory has a distinctive shaggy bark. The leaves are large, as are the nuts. Shagbark Hickory grows throughout the Eastern Deciduous Forest except on the Southern Coastal Plain.

Hickories are economically important tree. The wood is very hard and is used for tool handles and baseball hats. Many of the nuts are delicious. The Pecan is a commercial species of hickory. It is extremely difficult to remove the meat from most of the other hickory species, no matter how good they taste.