This medium to medium-large tree is 50-80' tall, consisting of a
straight trunk up to 3' across and a broadly oblongoid crown. The
branches in the upper part of the crown are ascending, while branches
in the middle part of the crown are horizontally spreading, and they
descending in the lower part of the crown. Trunk bark varies somewhat
according to the maturity of the tree. Young trees have relatively
coarse gray bark with irregular furrows and ridges, while the bark of
older trees is more shaggy from strips of bark curling outward from
their tips. Branch bark is light gray and more smooth; larger branches
have shallow furrows. Twigs are usually light brown and glabrous with
scattered white lenticels. Alternate compound leaves occur along the
twigs; these leaves are odd-pinnate with 7 leaflets (less often, they
have 5 or 9 leaflets). The compound leaves are typically about 12" long
and 8" across, although this varies with the size of the
Individual leaflets are 3-6" long and 1-2" across; they are
elliptic, lanceolate-elliptic, or oblanceolate-elliptic in shape, while
their margins are serrated. These leaflets have acute tips and usually
wedge-shaped bases (less often, their bases are round); they are
sessile, or nearly so (when they are present, petiolules are 3 mm.
in length or less). The upper leaflet surfaces are medium to dark
green, hairless, and shiny, while the lower leaflet surfaces are dull
olive-green and usually hairless (less often, they are slightly
pubescent). The hairless petioles and rachises of the compound leaves
are greenish white to red.
Sweet Pignut Hickory is monoecious, forming
separate male (staminate) and female (pistillate) flowers on the same
tree. The male flowers are produced in drooping catkins about 2-4"
long; they are produced near the tips of branches in groups of 3.
Individual male flowers have 4-10 stamens each; these stamens are
partially obscured by small 3-lobed bracts that are glabrous,
ciliate. Female flowers are produced in short spikes up to ¼"
(6 mm.) in length at the tips of branches; there are typically 2-3
flowers per spike. Female flowers are about 3 mm. in length, ovoid in
shape, greenish, and either hairless or pubescent; each female
flower has a calyx with 4 upper teeth and a pistil with broad stigmata.
The blooming period occurs from mid- to late spring for about 1-2
weeks. The flowers are cross-pollinated by the wind. Afterwards,
fertile female flowers develop into nuts with husks that become mature
during late summer or fall, when they fall to the ground. The nuts with
husks are ¾–1¼" long and a little less across; they are ovoid, obovoid,
or broadly ellipsoid in shape. Each husk consists of 4 segments
that are relatively thin; the husk surface is relatively smooth,
glabrous, and slightly warty. In addition, each husk is slightly winged
where its segments join together. At maturity, the husks split open
nearly to their bases to release their nuts. The nuts are broadly
ellipsoid, slightly compressed (flattened), slightly angular, and light
brown; their shells are thick. The meat of the nuts is white and mildly
sweet. The root system forms a woody taproot and more shallow lateral
The preference is full or partial sun, mesic conditions, and fertile
deep soil containing loam and organic material. However, other kinds of
soil are tolerated. This tree can live up to 250 years.
The native Sweet Pignut Hickory is
occasional in central
and southern Illinois, while in the northern section of the state it is
absent (see Distribution
). Illinois lies along the northern range
limit of this tree. Habitats include upland woodlands, wooded slopes,
bottomland woodlands in well-drained areas, woodland edges, overgrown
thickets, and limestone glades. This tree is found in proximity to
other deciduous trees, especially other Carya spp.
(Oaks). Sweet Pignut Hickory occurs primarily as scattered
trees, rather than in colonies, and so it is rarely dominant.
Occasionally this hickory is used as a landscape plant in parks, but it
is rarely used around homes and businesses.
Sweet Pignut Hickory and other hickory trees (Carya spp.
fair share of insects that feed on their leaves, wood, plant juices,
and nuts. The larvae of many beetles bore through the wood and
bark of these trees (see Wood-Boring Beetle Table
most of these
beetle species are in the Cerambycidae (Long-Horned Beetles). Other
insect feeders include the leaf beetles Cryptocephalus guttulatus
the larvae of Conotrachelus
and other plant bugs, the lace bug
(Black-Margined Aphid) and
(Black Pecan Aphid), several leafhoppers
(mostly Eratoneura spp.
miscellaneous treehoppers, Diapheromera
(Northern Walkingstick), and the caterpillars of
especially Catocala spp.
(Underwing Moths). See the Moth Table
list of these species. In addition, the caterpillars of two
(Banded Hairstreak) and Satyrium
(Hickory Hairstreak), feed on the foliage and
catkins of hickories.
Various birds and mammals eat the nuts of hickories. Among
birds, these species include the Blue Jay, American Crow, Wild Turkey,
Ring-Necked Pheasant, Bobwhite Quail, and Red-Bellied Woodpecker. The
primary consumers of hickory nuts among mammals are tree squirrels
(especially the Gray Squirrel, Fox Squirrel, and Southern
Flying Squirrel), although the Black Bear, Gray Fox, Raccoon, Eastern
Chipmunk, White-Footed Mouse, and Woodland Deer Mouse also eat the
nuts. The White-Tailed Deer occasionally browses on the twigs and
leaves of these trees, especially when they are saplings. Because of
the protective cover provided by the large leaves and shaggy bark, bats
sometimes select hickory trees for summer roosting sites and maternity
colonies, while the cavities within these trees are selected as
hibernation sites. Examples of bats that make use of these trees for
these purposes include the Red Bat, Hoary Bat, Keen's Bat, Twilight
Bat, Indiana Bat, Eastern Pipistrelle, and Rafinesque's Big-Eared Bat.
An overgrown thicket at Meadowbrook Park in
This hickory has received less attention than other species in its
genus because it is sometimes considered a variety of the Pignut
Hickory, or Carya
. Some authorities even refuse to
recognize it as a variety. However, the majority of botanists now
consider Sweet Pignut Hickory to be a distinct species, Carya ovalis
This tree should not be confused with the Shagbark Hickory (Carya
), which has a similar scientific name. Sweet Pignut
readily distinguished from Pignut Hickory by having more leaflets per
compound leaf (typically 7, rather than 5), shaggier bark (for mature
trees), and husks that divide nearly to the base of each nut when
they become mature. In addition, the petioles and rachises of the
compound leaves are often red, rather than greenish white. However,
this coloration can vary with the local ecotype of this tree. While the
bark of Sweet Pignut Hickory becomes somewhat shaggy with age, it is
still less shaggy than the bark of either Carya ovata
Hickory) and Carya
(Shellbark Hickory). It also has smaller
husked nuts than these latter two hickories. In addition to Sweet
Pignut Hickory, other common names of Carya ovalis
include Red Hickory,
False Shagbark Hickory, and Small-Fruited Hickory. The wood of this
tree is reddish brown or brown, heavy, hard, and strong. It is
used for many of the same purposes as the wood of other hickories,
including the construction of furniture and sporting equipment.