Pignut Hickory (Carya glabra)

Due to the extraordinary concentration of species diversity in the arboretum's relatively small space, we have a variety of fall foliage. Some of the trees have already changed color and dropped leaves, while others, most notably the maples and viburnums, are still in the process of showing us their fall colors. The evergreen palms and palmettoes will, of course, be best enjoyed next season, when the wintry landscape is bare and dreary.

But for now, the last two weeks of autumn, we must mention a tree that has gone too long without recognition. There is a handsome tree that produces a brilliant yellow display of leaves every autumn, but then for the rest of the year fades into the background; it requires zero maintenance and does not produce showy flowers or tasty fruits. It has no record in the arboretum catalogue, which means that this individual was not planted by either the current curator or the founder. Perhaps it is a volunteer. It may also have been intentionally planted prior to the founding of the arboretum. Examining its late-autumn guise, we can conclude that this tree is a pignut hickory (Carya glabra), and the below photos highlight its features. 

 

We first note a straight growth pattern. The trunk does not lean. The specimen is growing in rare full sun, next to a derelict lightpole. Classified as shade tolerant, this species would still prefer to get full sun. Its branches are horizontal or ascending, not drooping. We needed a ladder to collect leaves for identification.

Bark on the lower trunk is grey and textured. 

Detail; do you see a weaving or diamond pattern?

Long petioles alternate along the twig.

We see compound leaves, with 7 leaflets, measuring nearly a foot in length. Leaves are turning yellow. This species is recognized for its gorgeous fall foliage.

Leaflets vary in size, with the smallest leaflets at the base.

The terminal leaflet on this leaf measures nearly 5½ inches.

Leaflets have serrated margins. 

Underneath, we do not see the pretty yellow autumnal coloration. Leaflets and stem are pale and a little fuzzy.

Preliminary analysis points to Carya glabra, the pignut hickory. Let's officially start our list of 2026 goals: examine and make a digital record of spring leaves and flowers of this specimen, to strengthen our claim that this individual is a pignut hickory. Finding nuts belonging to this tree would help date it, as it takes more than 25 years of growth to reach maturity. Testing these nuts for edibility would also help, as they are particularly fatty and tasty, even among hickories. Although in the past this individual has produdced little to no fruit, 2026 is a new year with new surprises!

For more information about this species, please consult the following resources:

University of Florida 

Virginia Tech Dendrology 

Louisiana Plant Identification and Interactive Virtual Tours (LSUAgCenter) 

Volunteers in the Arboretum

As we continue to clean up the volunteer recruitment area and make it more accessible, we also document the species that have taken root in this green space. Since the volunteers are by necessity an unmanaged population, this is an interesting sample of what survives the struggle for existence.

This week we are clearing a path around a looming specimen: our only large, on-site native southern red oak (Quercus falcata). It is the large trunk pictured center. Most of its upper branches are out of the frame.

 

 

Seen from another vantage, the same mature southern red oak (Quercus falcata), and the red bricks of the Student Union Building are seen in the background.

Over the past few years, we haven't had a path around the base of this trunk.

Until today, the tree sign was hidden by the undergrowth. The area is thick with vegetation. Numerous volunteers are present with several different species represented.

Now, things have changed. First, the area was carefully surveyed for possible recruitments to the arboretum catalogue. This process involved weeding by hand―pulling up dewberry and snipping little trees. A few individuals, currrently very short in stature, were identified as candidates (we will let them grow up a little more before making it official). Then, this area was cut with a lawnmower to make a clear path.

Now, you can clearly see the sign.

Most of the volunteers around the southern red oak were removed or cut back to the ground. Only a few were left unharmed, and they are not visible in this photo. 

The photos below showcase the most conspicuous volunteers that were removed. These individuals were quick to colonize a new territory and were winning in the competition for survival. Unfortunately, they didn't germinate in a space deemed suitable by the arboretum curator.

chittamwood (Bumelia lanuginosa) REMOVED.... Although another chittamwood nearby will most likely be added to the arboretum's collection; it is located further away from the red oak's trunk.

oak (Quercus sp.) REMOVED

trident-leaf maple (Acer buergerianum) REMOVED

goldenrod (Solidago sp.) REMOVED

trumpet creeper (Campsis radicans) REMOVED

elm (Ulmus sp.) REMOVED

redbud (Cercis canadensis) REMOVED

nandina (Nandina domestica) REMOVED

non-native holly (Ilex sp.) REMOVED

red mulberry (Morus rubra) REMOVED

Mexican plum (Prunus mexicana) REMOVED

non-native privet REMOVED

Virginia creeper (Parthenocissus quinquefolia) REMOVED

dewberry (Rubus trivalis) REMOVED This species was heavily represented around the base of the red oak trunk; the ground was thick with dewberry. This species is very successful in the ground of the arboretum.