The pecan tree (Carya illinoinensis) is a large, deciduous species native to North America and is the largest member of the hickory genus. It is highly valued across the southern United States for its sweet, edible seed, which is often mistakenly called a nut. Identifying this tree relies on observing a specific combination of its physical traits throughout the seasons, including its foliage, fruit, and trunk.
Characteristics of Pecan Leaves
The foliage of the pecan tree is distinctive due to its odd-pinnately compound structure. The overall leaf is composed of multiple smaller leaflets arranged along a central stalk, terminating in a single leaflet at the tip. A mature leaf measures between 12 and 18 inches in length and features an alternate arrangement along the twig.
Individual leaflets typically range from 9 to 17 per leaf, exhibiting a lanceolate or slightly curved, sickle-like shape. Leaflet margins are finely serrated. The coloring is dark green on the upper surface, contrasting with a lighter green underneath. In the autumn, the canopy transforms into a consistent yellow before the leaves drop.
The Definitive Features of Pecan Nuts and Husks
The fruit of the pecan tree is the most conclusive identifying feature, especially when found attached to branches or on the ground in the fall. The pecan is technically a drupe, not a true botanical nut, where the edible kernel is enclosed within a hard shell. This shell is encased within a green, fleshy, four-valved outer husk.
As the fruit matures in late summer and early autumn, the green husk dries out and splits into four sections, releasing the shell-covered pecan. The exposed pecan is oblong or elliptical, with a smooth, medium to dark brown shell. The shell is notably thinner than those of many other hickory species. A ripe pecan feels heavy and full, and the kernel should not rattle loosely inside when shaken.
Identifying Pecan Bark and Overall Tree Structure
Pecan trees are known for their large size and broadly oval crown, typically growing to heights between 70 and 100 feet, sometimes exceeding 130 feet. The growth habit features a straight trunk and large limbs that spread outward and upward, creating an open canopy structure. This size and symmetrical shape become more pronounced as the tree ages.
The bark texture changes noticeably as the tree matures. Young trees have relatively smooth, slate-gray bark. This gradually develops into shallow fissures and thin, scaly ridges with age. The mature bark often has a gray-brown color flecked with lighter gray patches.
When the leaves are gone, the tree can still be identified by its distinctive terminal buds located at the end of the twigs. Pecan terminal buds are large, ovoid, and covered in yellow-brown, slightly hairy scales, often described as having a valvate appearance. This characteristic bud structure helps distinguish the pecan from true hickories, which typically have scaly, non-valvate terminal buds.