2022 Acorn Watch: Arkansas Oak (Quercus arkansana)

The acorns on our lone Arkansas oak (Quercus arkansana) are developing nicely! Below, we have a few photographs. Compare these with the photos from July, found here.

 

This tree isn't producing a lot of acorns, but a few are visible from the ground. They are difficult to find since the unripe acorn blends in with the green leaves and the small caps blend in with the twigs.

These acorns have shallow caps.

One potentially ripe acorn was found in the leaf litter. It's the right color for ripeness; however, the cap was still firmly attached. After the photoshoot, this little acorn was planted on the grassy slope near Cline Hall.

Tree of the Week: Arkansas Oak (Quercus arkansana)

 

As we continue our project, Acorn Watch 2022, we are looking at the arboretum's only Arkansas oak (Quercus arkansana). This tree is more than 25 years old. It was collected locally in Caddo Parish. In November 2021, we examined this individual and were happy to find a ripe acorn. At the time, we also found online that, according to the International Union for Conservation of Nature, this species is considered 'Vulnerable'. So, the acorns from the Arkansas oak are of extra special interest.

Looking for acorns can be a challenge. The tree must be old enough to produce acorns, which often means that the tree's lower branches have either been removed or dropped. Luckily, our Arkansas oak has a drooping branch with a couple of acorns. A ladder was used to take the pictures.

 

Here, we see dark green leaves and one immature acorn. The Student Union Building bricks are blurred in the background.

 

On this twig, we see two different cohorts of acorn, both immature. The larger acorn will ripen this year, and the smaller acorn will ripen next year.

 

So, how long will it take the larger ones to ripen? Can we expect ripe acorns in October or November? We shall see!

 

 

Tree of the Week: Arkansas Oak (Quercus arkansana)

 

The Arkansas oak (Quercus arkansana) is our tree of the week. There is only one Arkansas oak in the arboretum collection, and it has proved to be a resilient specimen. In May of 1996, it was collected as a seedling in northern Caddo Parish. It was nurtured in a pot for a year and then planted along the southern border of the arboretum. Two years later the little tree was dug up again. It was put back in a pot to avoid damage from the construction of Centenary College's new gym. In the spring of 2000, our tenacious Arkansas oak finally received a permanent spot in the arboretum, at the east corner of the Student Union Building.

 

Our tree of the week grows on a slope at the east corner of the Student Union Building. It is the tree with the noticeable lean in its trunk. We can't blame it for seeking the best exposure it can find to the scarce resource of sunlight.

The Arkansas oak has grown in direct competition with a Nuttall oak (Quercus texana), pictured to the right. The Nuttall oak is five to ten years older than the Arkansas oak.

 

From another angle, the Arkansas oak has a perfectly straight trunk, but the Nuttall oak, pictured left, still has a substantially thicker trunk.

 

Toward the base of the trunk, bark on the Arkansas oak is dark gray and very rough with no discernible pattern.

 

Above eye level, we see that the young bark has a different texture. It's still rough, but there are some smooth patches.

 

 

Arkasnas oaks have simple, alternate leaves.

 

 

alternate leaf arrangement of Quercus arkansana

Can you see the fuzzy texture on the twig?

Arkansas oak leaves vary in shape. Some resemble post oak leaves.

Unlike the post oak, the Arkansas oak is in the red-oak group. In this photograph you can see the bristle tips of the Arkansas oak leaves.

bristle tips of Quercus arkansana leaves

On November 7th, leaves are still dark green, but they lack their summer luster.

Leaves aren't big or showy, measuring under 4 inches in length, petiole included.

Underneath, leaves are visibly fuzzy, but do not particularly feel fuzzy.

One little acorn was found. This was the only acorn found attached to the tree. Perhaps there are more way up top, but none visible from below. A small number of acorns were found on the ground, but these could have belonged to the nearby Nuttall oak.

The small, round, striped acorn is half an inch long. According to the online literature, Quercus arkansana is a threatened species of oak. This little acorn ought to be planted!