Education & Outreach

An academic arboretum has two purposes. In its fundamental and most basic role, such an institution serves as a repository for living specimens and the germplasm of plant species. If this goal has been accomplished, a secondary role can be achieved: showcasing these specimens to students and the public, with the intention of increasing knowledge about those trees, shrubs, and herbs. Because they exist in physical space and not as a description in a book or on a computer, the arboretum's cataloged specimens can be seen year-round and from 360 degrees. You can "zoom in" and look as close as you want. Can't find just the right photo of a tree? Go snap one yourself at the arboretum. If you like the organism enough, you may be able to collect some seed and start your own. Short of cutting the specimen down or doing permanent damage, every plant in the arboretum is part of an interactive experience; no screens involved.

In support of this ideal, today we'll show some photos of a recent arboretum tour that Centenary College's Visual Identity and Publications Manager Sherry Heflin was kind enough to photograph. Normally, photos of tours given at the arboretum are not available, since the curator cannot photograph herself while thinking, walking, and speaking. Perhaps the arboretum needs a very expensive autonomous drone with a nice lens for such occasions. Then again, Skynet drones might disrupt the ambience for a group that is supposed to be experiencing nature. 

 All photos below were taken by Sherry Heflin, on October 21, 2024.

The tour began in the oldest part of the arboretum, between Hamilton Hall and the Student Union Building. One of the four black metal arboretum signs marks the northern edge of the arboretum.

For a tour during the fall, fruits are a great topic. The arboretum has many different species of oaks growing in a small area, so it's easy to find acorns and compare them. These small acorns were collected under a water oak (Quercus nigra).

This big acorn was snipped from a Burr oak (Quercus macrocarpa).

Persimmons are ripe this time of year! Here, the arboretum curator holds an example of a perfectly ripe persimmon (Diospyros virginiana).

French mulberry fruits are also edible, but not recommended. These pretty purple fruits weren't as numerous in late October.

The arboretum curator displays the very small seeds of the redbud (Cercis canadensis).

In the arboretum, there are plenty of opportunities to play the game: 'Where's the tree? Where's the vine?'. Here, the arboretum curator points out bright red fruits hanging from a black cherry (Prunus serotina). The bright red fruits actually belong to a vine, Carolina moonseed (Cocculus carolinus).

Ouch! These spiny fruits were produced by the American chestnut hybrid, Dunstan (Castanea dentata).

The arboretum has numerous red buckeyes trees (Aesculus pavia). Here, a Centenary students opens a buckeye fruit, looking for the large seeds.

Buckeye seeds are shiny and look oily. What do you think they smell like?

Competition over resources wasn't the focus of this tour, but a few examples were pointed out. Here we have an interesting example. Two trees are shown here. Their trunks have grown together. The slender trunk, leaning toward the left, belongs to a black oak (Quercus velutina). It was intentionally planted. The big trunk, growing straight up, belongs to a southern red oak (Quercus falcata). The red oak volunteered a few years after the black oak was planted, and the red oak has out-competed the black oak for sunshine, water and nutrients.

Even what looks like a bare stick is worth talking about. At the beginning of the tour, the arboretum curator explains that these is the arboretum's original patch of Hercules-club (Aralia spinosa), planted in the old part of the arboretum, circa 1990. Only three spindly plants remain.

Later in the tour, the arboretum curator points out a thriving grouping of Hercules-club. Here, the curator stands among the Hercules-clubs, holding two trunks. These plants are younger, and yet they are significantly larger. Viewing these plants in person and walking through the landscape, we can easily start to formulate hypotheses.

There is always something to talk about in the arboretum. The landscape is always changing!

Pretty mushrooms (Armillaria sp.)

Here we have a black oak (Quercus velutina), which we have previously covered on this blog. Wait. What's that at the base of the tree, nestled between the surface roots?

 

That's unusual. Is it a mushroom?

 

Yes! It's a cluster of orange mushrooms.

This appears to be a variety of Armillaria, but we don't know which species. Mushrooms are notoriously difficult to identify. This may be a fungus called "Oak Root Rot," which may or may not be a bad sign for the future vitality of our black oak. We later found four or five other clusters of mushrooms in various corners of the arboretum.

 

LSU AG Center's article on seasonal Armillaria

Tree of the Week: Black Oak (Quercus velutina)

Healthy trees are always growing, and in many cases, upward growth results in a loss of lower branches. It's no coincidence that the majority of mature trees in the arboretum lack their lower limbs. Healthy branches are often removed to make the landscape more accessible for foot traffic or, for safety concerns, to increase visibility. Some species take care of this for us; the trees naturally shed their lower limbs. Yet these dead branches don't immediately fall off a tree and may remain attached for years. While we normally allow these things to resolve themselves naturally and clean up the mess, sometimes we need to be proactive.

This past week, we decided to remove the unsightly dead branches from a black oak (Quercus velutina), located near the fitness center. This individual had accumulated a large number of dead branches, and since it's growing on the periphery of the arboretum, in a high-traffic area, we decided to improve its appearance. Here we show the results:

 

Our tree of the week is a black oak (Quercus velutina) that needed some cosmetic work done. This tree was planted near the Fitness Center less than 25 years ago but details of its planting history are unavailable.

 

A ladder was needed to do the tree trimming. These surface roots made it very difficult to position the ladder on solid ground. Be careful when doing this kind of work!

The surface roots are thick and bulbous, showing obvious signs of damage from lawn equipment.

Surface roots of Quercus velutina, photographed October 7, 2023

Surface roots of Quercus velutina, photographed October 7, 2023

Protruding from the ground makes these roots a sure target of lawnmowers and trimmers.

These dead branches started about eight feet above ground level and continued to around fifteen feet up. That required some climbing!

The tree looks a bit sparse, but much better overall.

With the dead branches removed, we can appreciate the black oak's straight trunk and dark bark.

These dead branches were all removed from one tree.

We will be watching this black oak over the next couple of months; we are expecting pretty fall foliage from it. Our appreciation of the color change won't be marred by those ugly dead branches.

And we have another reason to check-in with this tree in the coming months: acorns were spotted. Not many, and, of course, they are out of reach. Can you see one?

Quercus velutina acorn, photographed October 7, 2023

Tree of the Week Double Feature: Southern Red Oak (Quercus falcata) and Black Oak (Quercus velutina)

Last week we studied a green ash (Fraxinus pennsylvanica) that has grown and developed in a minimally competitive environment. The reduced competition has resulted in a very nice looking specimen, with a straight, strong trunk and uniformly oval crown. Since the tree stands alone, we are able to appreciate its overall form. You can find that post here.

This week, we have an interesting study of two oaks that have grown in direct competition with one another. The black oak (Quercus velutina) was planted first. In November 1995, this individual was collected as a seedling from the Caroline Dormon Nature Preserve (Bienville Parish). The following January it was planted in the ground of the arboretum, in its present location. Sometime later, a southern red oak (Quercus falcata) germinated in the same spot. One of the two is clearly the better competitor.

Pictured above, we have two different red oak species growing in the same spot. The skinny, leaning trunk belongs to the black oak, which is the older of the two. This tree was planted first with careful consideration. The southern red oak trunk is straight and significantly thicker. The precise age of the southern red oak is unknown, but we know that it is younger than the black oak and it has been in the catalogue since 2004.

Since the two trees have grown together, it's difficult to say much about the overall form of either specimen. For the most part, it appears that the southern red oak has suffered very little from cohabitation: the trunk is straight and the crown is nicely rounded at the top. However, if the black oak were completely removed, we might find that the southern red oak has a lopsided development. For the time being, this is a great spot to compare two different kinds of red oak leaves!

The upper surface of the southern red oak leaf is dark-green and smooth. This species is known for variability of leaf-shape, but all leaves are lobed with bristle-tips. This leaf measures more than 8 inches in length; the petiole measures a little less than 2 inches.

Underneath, southern red oak leaves are a dull brownish-green.

Southern red oak leaves are also fuzzy underneath. They are soft to the touch, rather than waxy like the upper surface.

This is a black oak leaf. It has a dark-green, smooth upper surface, and its shallow lobes are bristle-tipped. Its shape is clearly different from the deeply-lobed southern red oak leaf pictured above. However, keep in mind that, like the southern red oak, black oak leaves vary in shape, too. You can see some of this variety in a post about a different black oak, found here.

Underneath, black oak leaves are lighter in color and very soft to the touch.

The leaves on this black oak feel like velvet underneath, significantly softer than the leaves of the southern red oak.

Tree of the Week: Black Oak (Quercus velutina)

The arboretum has certainly been full of color this past week. Just to make sure nobody could ignore it, gusts of wind have thrown down multi-hued showers of leaves onto the lawns and paths. Our tree of the week is a stand-out specimen in this autumnal display; the black oak (Quercus velutina) has turned red-orange.

Our tree of the week is growing in full-sun, at the bottom of a slope, near the concrete drainage. Specifics about this tree's planting date and acquisition are unknown, but it was certainly planted after the completion of the Fitness Center. This upper limit for age makes the tree less than 20 years old. No evidence of acorns this year.

This black oak has an upright trunk, a pyramidal form, and a dark trunk. From a distance, the leaves appear to be of one uniform red-orange color.

But upon closer inspection the leaves appear more brown.

These leaves are still in transition from green to autumn shades.

On one leaf we see red, orange, yellow, and green. 

Black oak leaves have shallow lobes and bristle-tips.

Consumer warning: your leaf size may vary.

Underneath, the leaves are fuzzy along the midrib.

The pointy buds are fuzzy, too.

The bark of this specimen is almost black.

Simple property damage: someone, most likely (and hopefully) a squirrel, has been gnawing on the black oak sign. 

You can find more photos of the arboretum's black oaks here.

For more information about this species consult the following:
Fire Effects Information System (US Forest Service)
Virginia Tech Dendrology
NC State University