The pear-shaped nut ripens in September and October, has a sweet maple like smell, and is an important part of the diet of many wild animals.

Pignut makes up much of the hickory harvested in Kentucky, West Virginia, the Cumberland Mountains of Tennessee, and the hill country of the Ohio Valley.

Average snowfall varies from little to none in the South to 2,540 mm (100 in) or more in the mountains of West Virginia, upstate New York, and western North Carolina (25).

According to one classification of climate (20), the range of pignut hickory south of the Ohio River, except for a small area in Florida, is designated as humid, mesothermal.

Pignut hickory frequently grows on dry ridgetops and sideslopes throughout its range but it is also common on moist sites, particularly in the mountains and Piedmont.

In the Great Smoky Mountains pignut hickory has been observed on dry sandy soils at low elevations.

This site is the most xeric habitat on the mountain because of high insolation, 70 percent slopes, and medium- to coarse-textured soils derived from Clinch sandstone.

About two-thirds of the species range is dominated by Ultisols, which are low in bases and have subsurface horizons of clay accumulation.

Pignut hickory responds to increases in soil nitrogen similarly to American beech (Fagus grandifolia), sugar maple (Acer saccharum), and blackgum (Nyssa sylvatica).

Hickories are consistently present in the broad eastern upland climax forest association commonly called oak-hickory, but they are not generally abundant.

It has been hypothesized that hickory will replace chestnut (Castanea dentata) killed by the blight (Cryphonectria parasitica) in the Appalachian Highlands.

On Beanfield Mountain in Giles County, Virginia, the former chestnut-oak complex has changed to an oak-hickory association over a period of 50 years.

The staminate catkins of pignut hickory are 8 to 18 cm (3.1 to 7.1 in) long and develop from axils of leaves of the previous season or from inner scales of the terminal buds at the base of the current growth.

The pistillate flowers appear in spikes about 6 mm (0.24 in) long on peduncles terminating in shoots of the current year.

Flowers open from the middle of March in the southeast part (Florida) of the range to early June in Michigan.

Husks of pignut hickory split only to the middle or slightly beyond and generally cling to the nut, which is unribbed, with a thick shell.

Hickories exhibit embryo dormancy which is overcome naturally by overwintering in the duff and litter or artificially by stratification in a moist medium at 1 to 4 °C (34 to 39 °F) for 30 to 150 days.

Hickories are hypogeously germinating plants, and the nuts seldom remain viable in the forest floor for more than one winter.

Internal discolorations called mineral streak are common and are one major reason why so few standing hickories meet trade specifications.

Streaks result from yellow-bellied sapsucker pecking, pin knots, worm holes, and mechanical injuries.

The most common disease of pignut hickory from Pennsylvania southward is a trunk rot caused by Poria spiculosa.

On large trees these may become prominent burl-like bodies having several vertical or irregular folds in the callus covering.

The stem canker (Nectria galligena) produces depressed areas with concentric bark rings that develop on the trunk and branches.

Affected trees are sometimes eliminated through breakage or competition and sometimes live to reach merchantable size with cull section at the canker.

A gall-forming fungus species of Phomopsis can produce warty excrescences ranging from small twig galls to very large trunk burls on northern hickories and oaks.

More than 100 insects have been reported to infest hickory trees and wood products, but only a few cause death or severe damage.

The false powderpost beetle (Xylobiops basilaris) attacks recently felled or dying trees, logs, or limbs with bark in the Eastern and Southern States.

A few of the more common species of gall-producing insects attacking hickory are Phylloxera caryaecaulis, Caryomyia holotricha, C. sanguinolenta, and C. tubicola.

The principal difference is in the husk of the fruit, opening late and only partly, or remaining closed in C. glabra but promptly splitting to the base in C. ovalis.

The relationships may be more complex after a long and reticulate phylogeny, according to detailed chemical analyses of hickory nut oils.