Ohio State University Extension Bulletin

Ohio Trees

Bulletin 700-00


Carya – Hickory

Hickories are deciduous trees with branches having solid pith. Terminal buds bear imbricate, scaly buds except in the bitternut hickory which has valvate or foliate buds. Leaves are alternate with the leaflets arranged in an odd-pinnate pattern. Male flowers are borne in catkins. Female flowers are borne on the same tree (monoecious) but are inconspicuous. Fruit is a husked nut and is often edible.

Key to Carya Species

I. Buds are valvate to foliate and sulphur yellow in color. Leaflets are 3 1/4—6 inches (8 1/2—15 cm) long. Five to nine leaflets are borne in an odd-pinnate pattern. Leaf scars are large and broad.
 

Carya (Hicoria) cordiformis–Bitternut Hickory

II. Buds have overlapping scales. Three to nine leaflets are borne in an odd-pinnate pattern. Branches are stout and coarse. Leaf scars are large and circular.
  A. Terminal buds are small, 1/4—1/2 inch (6—13 mm) long.
    |. Branchlets and leaflets are glabrous. Leaves have three to seven, usually five, leaflets. Bark is dark gray, fissured, and tightly held.
      Carya (Hicoria) glabra–Pignut Hickory
    ||. Branchlets and leaflets are scarcely pubescent. Leaves have five to seven, usually five, leaflets. Bark is dark gray, fissured, and closely held.
      Carya ( Hicoria) ovalis–Red Hickory
  AA. Terminal buds are larger and are 1/2—1 inch (13—25 mm) or longer.
    |. Twigs are densely woolly, or hairy, and bright brown in color. Leaves contain seven to nine leaflets. Foliage is very fragrant when crushed. Bark is ridged and closely held.
      Carya (Hicoria) tomentosa–Mockernut Hickory
    ||. Twigs are glabrous, or only slightly hairy, when young. Bark is shaggy and breaks into plates that are shed.
      a. Leaves have five, rarely seven, leaflets. The upper leaflets are larger than the lower ones. Twigs have light reddish-brown bark.
        Carya (Hicoria) ovata– Shagbark Hickory
      aa. Leaves have seven to nine leaflets. Twigs have orange bark.
        Carya (Hicoria) laciniosa–Shellbark Hickory

Description of Species

Bitternut Hickory–Carya (Hicoria) cordiformis

The bitternut hickory is a tall tree with a broad, pyramidal crown, attaining a height of 100 feet and a diameter of 2—3 feet. This tree is common throughout the state and is found in moist forests and flood plains. It is well known by its round, bitter nuts. Hickories with valvate or foliate buds are known as pecan hickories and are generally vase-shaped in habit.

Bitternut Hickory   Bitternut Hickory   Bitternut Hickory
Bitternut Hickory

The bark on the trunk is granite gray, faintly tinged with yellow, and less rough than most other hickories. Bark is broken into thin, platelike scales. The winter buds are valvate to foliate, scurfy, bright yellow, and quite different from those of other hickories. The winter bud is an outstanding identification feature. This tree is more closely related to pecan than to shagbark hickory.

The leaves are alternate and odd-pinnately compound. Leaves are from 6—10 inches (15—25 cm) long and composed of five to nine leaflets. The individual leaflets are 3 1/4—6 inches (8 1/2—15 cm) long and smaller and more slender than those of the other hickories. Leaf scars are large and broad.

The flowers, like those of all the hickories, are of two kinds on the same tree. Male catkins are conspicuous, while the female flowers are small and easily overlooked. The fruit is about 1 inch (2 1/2 cm) long and thin-husked. The nut itself usually has a thin shell that is brittle. The kernel is very bitter and not considered edible. The wood is hard, strong, and heavy.

Pignut Hickory–Carya (Hicoria) glabra

The pignut hickory is a medium to large, upland tree occurring plentifully in all parts of the state. It has a tapering trunk and a narrow, oval head.

Mature bark is closely held, ridged, and dark gray but occasionally is rough and flaky. The twigs are thin, smooth, and glossy brown. The polished, brown winter buds are egg-shaped. Branches are stout and coarse. The outer, reddish-brown scales fall in the autumn. Overwintering buds have overlapping scales. Terminal buds are small and only 1/4—1/2 inch (6—13 mm) long. Leaf scars are large and circular.

Pignut Hickory   Pignut Hickory
Pignut Hickory

The leaves are smooth, 8—12 inches (20—30 1/2 cm) long, and composed of five to seven, usually five, leaflets. Leaflets are borne in an odd-pinnate pattern. The individual leaflets are 3—6 inches (7 1/2—15 cm) long and 1—2 inches (2 1/2—5 cm) wide. Fall color is a golden yellow.

Flowers are monoecious. Male flowers are catkins and showy, while the female flowers are green and inconspicuous. Flowering occurs in May. The fruit is pear-shaped or rounded, usually with a neck at the base. Thin husks split only half way to the base or not at all. The nut is smooth, light brown in color, rather thick-shelled, and has an edible kernel. The wood is heavy, hard, strong, tough, and flexible. Pignut hickory lumber uses are the same as those of the other hickories.

Shellbark Hickory
   Shellbark Hickory
 

Shellbark Hickory–Carya (Hicoria) laciniosa

The shellbark hickory, or king nut hickory, is primarily confined to central and southern Ohio and is rare in the northern part of the state. It is similar in appearance to the shagbark hickory, but is smaller in stature. It is a distinct tree of coves and richer slopes. Shellbark hickories tolerate moister sites than do the shagbark hickory. The lower branches of this stately hickory are drooping and clothed with large leaves.

Twigs are much stouter and glabrous, or only slightly hairy, when young with orangish-brown bark. The bark of the trunk is shaggy with long thin strips separating from the trunk, as does the shagbark hickory. The winter terminal buds are imbricate and sometimes nearly 3 inches (71/2 cm) in length.

The leaves are alternate, odd-pinnately compound, and vary from 10—24 inches (25—61 cm) in length. Leaves are composed of five to nine, usually seven, leaflets on a leaf stalk that is abruptly thickened at the base. The leaf base remains after the leaflets fall and often curls backward. The oblong to lanceolate leaflets are larger than shagbark hickory and range from 4—10 inches (10—25 cm) in length.

Flowers are monoecious. Male flowers are catkins and showy, while the female flowers are green and inconspicuous. Flowering occurs in May. The fruit of this species is a nut enclosed in a thick, hard husk that splits into several pieces. It is prominently four- to six-ridged, or angled, and somewhat flattened. The nuts are larger than shagbark hickory and are borne singly or in pairs. Nuts average from 1—2 inches (2 1/2—5 cm) in length. The kernel of the shellbark hickory is light brown, sweet, and in demand as a food. Shellbark hickory is second in popularity to pecan.

The wood differs little from that of the shagbark hickory. It is heavy, hard, tough, very strong, and used for many purposes requiring a wood of unusual strength, hardness, and toughness. Hickories produce excellent firewood.

Red Hickory–Carya (Hicoria) ovalis

The red hickory tree is very similar to the pignut hickory. It thrives in the same areas as the pignut, and is often hard to distinguished from the pignut hickory. Many people consider red hickory to be a northern ecotype of the pignut hickory. At maturity, the red hickory attains a height of 50—80 feet with a trunk diameter of from 2—3 feet. The crown is narrowly oblong with rather short, spreading branches. Lower branches are drooping. The trunk extends straight into the crown and is often forked.

Buds are small and only 1/4—1/2 inch (6—13 mm) long. Branchlets and leaflets are scarcely pubescent. The bark is dark gray, fissured, and closely held on young trees. Mature bark separates into narrow, shaggy plates on older trunks, but even these plates are more tightly held than shagbark and shellbark hickories. This character give rise to the name of false-shagbark hickory.

The leaves are 8—12 inches (20—30 1/2 cm) long. They are composed of five to seven leaflets which are oblong or rounded to lance-shaped, 3—5 inches (7 1/2—13 cm) long, and 1—2 inches (2 1/2—5 cm) wide. Leaflets sharply taper at the apex and are finely serrate, or toothed, along the margin.

Flowers are monoecious. Male flowers are catkins and showy, while the female flowers are green and inconspicuous. Flowering occurs in May. The fruit is subglobose, from 4/5—1 inch (20—25 mm) long, and four-channeled from the apex to the base. Fruits are light brown and scaly when ripe. The husk is thin and is difficult to split. The nut is brownish in color with a small, sweet kernel.

This tree is found on lower slopes of southeastern Ohio rather than the ridges where the pignut hickory is found. Red hickory is particularly common on southern and western exposures. The wood is heavy, strong, and hard. It is reddish-brown in color which gives this plant its local name of red hickory. It is said to be somewhat inferior to the other hickories but is used for the same purposes.

Shagbark Hickory
   Shagbark Hickory
 

Shagbark Hickory–Carya (Hicoria) ovata

The shagbark hickory is well-known because of its sweet and delicious nuts. It is a large, commercial tree, averaging 60—100 feet high and 1—2 feet in trunk diameter. The shagbark hickory thrives on rich, damp soil and is common along streams and on moist hillsides throughout the state.

The terminal winter buds are egg-shaped and 1/2—1 inch (13—25 mm) long. Outer bud scales have narrow tips on the scales. Twigs are glabrous, or only slightly hairy, when young and have a light reddish-brown color. The bark of the trunk is rougher on shagbark and shellbark than on the other hickories. Mature bark color is light gray, and the bark separates into thick plates which are only slightly attached to the tree. The mature bark gives this tree its common name.

The leaves are alternate, odd-pinnately compound, and from 8—15 inches (20—38 cm) long. Leaves are composed of five, and rarely seven, obovate to ovate leaflets. The upper leaflets are larger than the lower ones.

The flowers are monoecious and open after the leaves have nearly attained their full size. The globular fruit matures in November and is borne singly or in pairs. The husk is thick and deeply grooved at the seams. The nut is compressed and pale. The shell of the nut is thin, and the kernel is sweet. The kernel can be used as a substitute for pecan but is less favored than shellbark hickory.

Littlenut shagbark hickory, Carya (Hicoria) tomentosa nutalli, is a variety of the common shagbark, although the bark and form of the tree show practically no difference. This variety is identified entirely by the shape and size of the fruit. The nut is described as being "rounded." It is rarely pointed at top, although it may be either rounded or abruptly pointed at the base. The nut is heavily compressed, sharply angled, and about 3/4 inch (2 cm) long and 1/2 inch (13 mm) thick.

The wood is heavy, hard, tough, and very strong. It is used largely in the manufacture of agricultural implements and tool handles. For fuel, the hickories are the most satisfactory of our native trees. The dense wood gives off much heat.

Hickories are tolerant of construction and human activity. This tree is likely to survive the construction of a home on the site. Trees in a landscape often predate the home. Hickories are slow growing and difficult to transplant, thus this tree is rarely found in nurseries.

Mockernut Hickory–Carya (Hicoria) tomentosa (alba)

The mockernut, white hickory, whiteheart, or bigbud hickory is commonly found on well-drained soils throughout the state. It is tall, short-limbed, and averages 60 feet in height and 1—2 feet in trunk diameter. The tree has an upright habit even when grown in the open.

Mockernut Hickory   Mockernut Hickory
Mockernut Hickory

The winter buds are about an inch (2 cm) long, round, or broadly egg-shaped, and covered with downy, hard scales. The recent twigs are short, stout, and more or less covered with downy hairs. Twigs are bright brown in color. The mature bark is dark gray, hard, closely, and deeply furrowed, often apparently cross furrowed or netted. Bark is closely held and very different than the shellbark and shagbark hickories.

Odd-pinnately compound leaves contain seven to nine leaflets. Leaves range from 6—12 inches (15—30 1/2 cm) long. The upper leaflets are larger than the lower ones. Foliage is very fragrant when crushed. Foliage is densely pubescent beneath, giving rise to the scientific name.

The flowers, like those of all other hickories, are monoecious. The male flowers are borne in three-branched catkins. Female flowers are borne in clusters of two to five in May. The fruit is oval, or nearly round, to slightly pear-shaped. Fruits have a very thick, strong-scented husk which splits nearly to the base when ripe. The nut is of various forms, but is sometimes four- to six-ridged. The color is light brown and the nut has a very thick shell with a small, sweet kernel.


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