Pignut hickory (Carya glabra): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table.

At a glance

Item	What the source records
Scientific name	Carya glabra (Mill.) Sweet in USDA PLANTS, walnut family
Other names	Pignut, sweet pignut, coast pignut hickory, smoothbark hickory, swamp hickory and broom hickory (Silvics)
Native status, USDA PLANTS	Native in Canada and the lower 48 states
Size, Silvics	Often 24 to 27 m (80 to 90 ft) tall and occasionally 37 m (120 ft), with a diameter at breast height of 91 to 122 cm (36 to 48 in); the bole is often forked
Fruit, Silvics	Pear-shaped fruit in a thin husk that ripens in September and October; the husk splits only to the middle or slightly beyond and generally clings to the unribbed, thick-shelled nut
Green weight of the wood, NRS-38	68 lb per cubic foot, without bark

Native range

The Silvics of North America handbook (Agriculture Handbook 654, volume 2, 1990) says the range of pignut hickory covers nearly all of the eastern United States. It runs from Massachusetts and the southwest corner of New Hampshire west through southern Vermont and extreme southern Ontario to central Lower Michigan and Illinois, south through extreme southeastern Iowa, Missouri and Arkansas to Louisiana and parts of East Texas, and east along the Gulf Coast to Mississippi and Alabama and into central Florida. Best development is in the lower Ohio River Basin, and the handbook calls it the hickory most commonly found in the Appalachian forests. It says 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.

Flowers and fruit

Silvics says hickories are monoecious and flower in spring. The male catkins of pignut hickory are 8 to 18 cm (3 to 7 in) long and the female flowers are spikes about 6 mm (0.25 in) long on shoots of the current year. Flowers open from the middle of March in the southeast part of the range to early June in New England, and the catkins usually emerge before the female flowers. The handbook says seeds are dispersed from September through December. The nuts are an important part of the diet of many wild animals, and the handbook reports that squirrels get an estimated 10 to 25 percent of their diet from hickory nuts.

Roots

The handbook says pignut hickory tends to develop a pronounced taproot with few laterals and rates it as windfirm. The taproot develops early, which the handbook suggests may explain the slow growth of seedling shoots, and taproots may develop in compact and stony soils.

Wood

The Wood Handbook (FPL-GTR-282, 2021) names pignut with shagbark, shellbark and mockernut as the true hickories most important commercially. What it says about the white sapwood, reddish heartwood and uses such as tool handles is set out once on the shagbark hickory page. Silvics adds that hickory has a relatively high heating value and is used extensively as a home heating fuel, and that pignut is an important shade tree in wooded suburban areas over most of the range but is seldom planted as an ornamental. Table 5-3b has a separate pignut row, shown below.

Wood Handbook Table 5-3b	Specific gravity	Modulus of rupture (lbf per square inch)	Side hardness (lbf)
Green	0.66	11,700	1,520
At 12% moisture content	0.75	20,100	2,140

The Wood Handbook states that specific gravity is based on oven-dry weight and the volume when green or at 12% moisture content. The green weight of the wood without bark is in the NRS-38 table, the same figure used in the log weight calculator.

Diseases, insects and damage the handbook names

Silvics (1990) says the Index of Plant Diseases in the United States lists 133 fungi and 10 other causes of disease on Carya species, most of the fungi being saprophytes, and that more than 100 insects have been reported on hickory trees and wood products but only a few cause death or severe damage.

Fire. The handbook says pignut is easily damaged by fire, which causes stem degrade or loss of volume or both.
Mineral streak. Internal discolorations called mineral streak are common and are one major reason so few standing hickories meet trade specifications. Silvics says streaks result from yellow-bellied sapsucker pecking, pin knots, worm holes and mechanical injuries.
Trunk rot. The most common disease of pignut hickory from Pennsylvania southward, caused by Poria spiculosa. The handbook describes cankers whose size and look vary with age, including a form around a branch wound that resembles a swollen, nearly healed wound.
Leaf diseases. Anthracnose (Gnomonia caryae), which causes brown spots with definite margins on the undersides of leaves, and mildew (Microstroma juglandis), which may form witches' brooms. The handbook says the mildew is locally prevalent but offers no problem in the management of hickory.
Cankers and galls. The stem canker Nectria galligena produces depressed areas with concentric bark rings on trunks and branches, and a gall-forming Phomopsis species can produce warty growths from small twig galls to very large trunk burls on northern hickories and oaks. The handbook says little information is available on root diseases of hickory.
Hickory bark beetle. Scolytus quadrispinosus, which Silvics calls the most important insect enemy of hickory and one of the most important insect pests of hardwoods in the eastern United States. It says outbreaks during drought in the Southeast have killed large tracts of timber and that the foliage of heavily infested trees turns red within a few weeks of attack.
Other insects. The ambrosia beetle Platypus quadridentatus and the false powderpost beetle Xylobiops basilaris in logs and dying wood, the twig girdler Oncideres cingulata, and gall makers including Phylloxera caryaecaulis and three Caryomyia species.

Silvics also says hickories strongly resist ice damage and seldom develop epicormic branches.

The guide on reporting a pest in the United States and the Canada reporting page give the offices that take sightings of regulated pests. Who may apply pesticides is in pesticide licences by country.