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!

2022 Acorn Watch

 

We have more post oak (Quercus stellata) acorns to add to our on-going germination project. These acorns were collected this past week in the Piney Woods region of East Texas, south of Jacksonville. They've since been potted, so now we wait to see who sprouts and who doesn't.

These water oak (Quercus nigra) acorns were collected at the same time from the same property. They have been potted as well. The arboretum is currently home to seven mature, on-site native water oaks, but we do not currently have any young water oaks in the collection.

Hurricane Laura Damage: Upper Pond

In late August, during the Hurricane Laura weather event, the arboretum suffered a minor catastrophe in the upper pond. A large limb broke from the crown of a mature water oak (Quercus nigra), crushing beneath it several medium-sized trees. Such a mess resulted that it's difficult to discern from photographs what exactly took place.

All of the damage can be traced back to this mature water oak (Quercus nigra). At the top, the trunk divides into four large branches. One of these branches snapped off during the storm.

The branch fell towards the pond, landing on several medium-sized trees. It remained suspended on a bent sweetbay magnolia (Magnolia virginiana).

The weight of the oak branch bends the sweet bay magnolia over the gravel path.

One sweetbay magnolia is bent over the path, while a nearby sweetbay completely lost its crown.

After more than two weeks of clean-up, things are back to normal in the arboretum. Hurricane Laura changed the look of the upper pond. The old water oak lost a very big, mature limb, and two sweetbay magnolias had to be completely removed due to the excessive damaged they suffered. As a result, more light will now hit the vegetation growing in and around the wet area. 

Younger, smaller trees have been lying in wait for such a moment. Hundreds of redbay seedlings would love the opportunity to fill the gap left by the two sweetbays. A spindly big-leaf magnolia struggled for years in the shade, and a laurel-cherry, who happily grows in the shade, now has the extra sunlight to grow tall. Over the past decade, powdery thalia has all but disappeared in the upper pond due to the advancing shade created by maturing trees. Perhaps it will return. For now, the plan is to prevent each and every little redbay from growing in the upper pond, while at the same time encouraging the big-leaf magnolia, laurel-cherry, and thalia.

Upper Pond, September 2020

Upper Pond, September 2020

East side of Upper Pond, September 2020

Water Oak Acorns

This accumulation of water oak (Quercus nigra) acorns might go unnoticed; it blends in with the gravel path. These acorns were found under two large, on-site native water oaks growing near the top of the arboretum drainage, east of the Student Union Building.

The acorns are the size of blueberries. It is doubtful that they are of comparable taste.

Three acorns from the left to right: white oak (Quercus alba), swamp white oak (Quercus michauxii), and water oak (Quercus nigra)

The water oak acorns look less blue with a light-colored background, but still small.

All photos taken on December 2, 2018.

Tree of the Week: Water Oak (Quercus nigra)

A couple of gusty summer rainstorms blew through town earlier in the week. As well as wetting the thirsty ground, all our trees got their limbs rustled. Naturally, a few branches were knocked loose. Fallen twigs of the older trees are of special interest because they are normally far out of reach for inspection. This week we were afforded the opportunity to examine the seasonal progress of the water oak (Quercus nigra).

There are seven water oaks in the arboretum collection. All are on-site natives, pre-dating the institution of the arboretum. These are big, mature trees without lower limbs. From the windfall of branchlets we can see that the water oaks growing near Hamilton Hall are having a highly productive year for acorns. The pictures below are of one individual; the photos were taken on a sunny day at noon.

Most of the year, this is all we notice of the water oaks -- big, cylindrical, gray trunks. Because all of the water oaks in the arboretum are old trees with no lower branches, there is nothing ro lure the eye.

The bark is dark gray with shallow grooves.

This water oak, pictured center, grows near Hamilton Hall. This is a very shady spot. At noon on a sunny day we only see dappled sunlight under the old oak. 

The water oak grows at the top of a gradual, clay slope.

We see lots of immature acorns on the fallen twigs.

Leaves alternate along the twig.

The immature acorns are green and very small, approximately a quarter of an inch in length.

Water oak leaves are small, wedge-shaped, and dark-green. Leaf margins are wavy, but smooth.

Underneath, the leaves are green and smooth with a few (very small) fuzzy spots.

For more information about this species consult the following:
United States Department of Agriculture -- zoom-in on map!
Virginia Tech Dendrology
Louisiana Plant Identification and Interactive Virtual Tours

This past Wednesday a lot of rain fell, accompanied by some gusts of wind. A couple large, dead branches were knocked loose and fell to the ground with the rain. Luckily for us, some branchlets fell, too, giving us a look at this year's growth from the tip-top of the old trees. 

White oak (Quercus alba) leaves and acorns

This bristly fruit fell from the hybrid American chestnut tree (Castanea dentata). Ouch! We aren't going to bust it open quite yet.

Water oak (Quercus nigra) acorn and leaves.

The sweetgum (Liquidambar styraciflua) often acquires a bad wrap because of its pointy fruits. There is one large on-site native sweetgum in the arboretum collection, and, admittedly it does make a mess of the sidewalks. It has sustained damage over the years, so this past summer a volunteer sweetgum growing up in the groundsel bush (Baccharis halimifolia), away from foot traffic, was admitted into the catalogue, so that we have a back-up specimen should something happen to the old one.

This image shows the relative size of the different fruits.

The fruit pods of the strawberry bush (Euonymus americanus) are changing color and opening up.

The orange-red seeds of the strawberry bush are revealed. They should not be eaten!

Quercus nigra