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.

Black and Yellow Garden Spider (Argiope aurantia)

Boo! Autumn is a season for creepy-crawlies, spiders, and bugs. This is a female Argiope aurantia, which is Latin for 'golden silver-face.' This name makes a lot of sense, given that the cephalothorax (meaning head-body) is silver while the abdomen is gold and black. We know it's not a male because males of the species are much smaller, brown, and just plain ugly.

"Oh... what tangled webs we weave...." As members of the Araneidae family, these spides are "orb-weavers" and produce the classic spider-web.

This specimen was photographed on September 28, 2024, next to the long white wooden bridge in the arboretum.

 

For comparison, this photo is from insectidentification.org (image credit: Arch Baker).

Volunteers in the Arboretum

The overgrown area near the Student Union Building, previously referred to as 'the volunteer recruitment zone' or 'the Arboretum's unintended creche', is slowly being cultivated: we have removed Groundsel shrubs (Baccharis halimifolia) and Chinese privet (Ligustrum sinense). This week, we cleared around the sycamore (Platanus occidentalis), making it possible to read the sign and walk around the trunk.

The arboretum has only one sycamore on display, so we want to raise this tree's profile. Visitors ought to be able to read the sign and examine the trunk without too much difficulty. Right now, it looks a bit too hazardous; you might come away with some dewberry-scratches on your shins. 

There are numerous vines, little shrubs, and trees growing around the base of the trunk. Unfortunately they must be removed for the health and visibility of the sycamore.

The base of the trunk is now revealed. Several small trees were removed; elms (Ulmus sp.), oaks (Quercus sp.), and one black cherry (Prunus serotina) were snipped. We do not want any other trees to grow up next to the sycamore trunk, so it was an easy decision to remove these volunteers.

We used a lawn mower to cut the grass, making this space more inviting to foot traffic.

Several pieces of crossvine (Bignonia capreolata) had to be pulled from the trunk.

Dewberry (Rubus trivialis) was cleared away from the base of the trunk. This species comprised the bulk of the plant material surrounding the tree.

Dewberry vines have painful spines. It's best to wear long pants when walking near a dewberry patch, but as the spines get caught on clothes, you still need to watch your step even if dressed defensively.

A small yaupon holly (Ilex vomitoria) was growing near the trunk, but not next to it. Yaupons do very well in the soil of the arboretum and they are common volunteers. This little shrub was allowed to stay for now and might very well be added to the catalogue.

Luckily, there were not any passionflower vines surrounding the sycamore. The abundance of Gulf fritillary butterflies tells us that we ought to refrain from pulling any passionflower―we want the caterpillars to have plenty to eat!

Cleanup Operations

Today, more than four months since it fell, we decided to complete the water locust (Gleditsia aquatica) clean-up operation. Most of the mess was cleared away during the month of May. Over the summer, a very large section of the trunk remained wedged inside the yaupon holly on which the water locust had collapsed.

 

A section of the water locust trunk is pictured on the far right of the photograph. It had been resting in the yaupon holly shrub for several months.

 

As this tree trunk was suspended off the ground, we are "stumped" as to its current rotted condition. There are numerous mushrooms growing on it. Why would a rot-resistant tree have rotted so quickly?

 

A chainsaw was required to reduce the trunk to movable pieces.

All cleaned up! The water locust is gone, which is sad, but the good news is that we have a young water locust to plant this winter.

Arboretum Cleanup: Catalpa (Catalpa bignonioides)

Maintaining trees in an urban landscape often requires pruning. Removing lower branches from trees allows for more foot traffic in proximity to the trees, and it also increases visibility, which is a safety concern. Some trees require more pruning than others. Today we'll take a look at one of our catalpas, which is in rude health. See previous posts on the history of this tree here and here.

 

The catalpa (Catalpa bignonioides) is pictured center. What a gorgeous tree. It is only eleven years old! Take a look at the trunk: there aren't any branches near the ground.

Even though the lower branches have been removed from the trunk, branches further up the trunk droop low to the ground.

The leaves and seed pods are only a couple of feet above the grass.

 We pruned this tree and its partner (not photographed), which lies across the drainage canal. With the lowest drooping branches removed, we see more of the landscape, and, more light is now available to the little trees and shrubs recently planted. The catalpa will hopefully invest its energy in its upper branches rather than the ones nearest the ground.

Kentucky Coffee-Tree (Gymnocladus dioica)

In our contemporary situation of free and easy global trade, yearly consumption of coffee beans amounts to almost 25 billion pounds. You can get a cup almost anywhere, anytime. But since Coffea arabica can only be grown in a relatively few environments, war or trade embargoes can easily cut off coffee supplies to most places on earth. Due to this problem and the recognized benefits of the drink, coffee substitutes have often been sought and utilized. Today we'll showcase the arboretum's Kentucky coffee-tree (Gymnocladus dioica). 

 

It isn't native to Louisiana. The map below shows that the plant is really a Midwestern fellow, with its distribution dipping down into the southeast. 

This map shows the current distribution according to the USDA-NRCS. The Kentucky coffee-tree (Gymnocladus dioica) does not typically grow in Louisiana. Since it can be found in central Arkansas, this species certainly deserves representation in the Centenary arboretum.

There are two Kentucky coffee-trees growing in the arboretum. There is a big one, and right next to its trunk, there is a little one, which is clearly waiting for one of the surrounding trees to die so that it might have a chance to grow. These two trees do not have an official entry in the arboretum catalogue. They are mentioned elsewhere, in regards to other plants, but their specific planting history is missing. In an entry for spiderwort, the Kentucky coffee-tree is mentioned: "Another large clump [of spiderwort] with the seedling Gymnocladus dioica, below iris bed in west floodplain, planted 1999." A Kentucky coffee-tree seedling was growing in a pot with spiderwort, and they were planted together in the west floodplain in 1999. So, the Kentucky coffee-tree is at minimum 25 years old. According to the Iowa University Agriculture and Natural Resources Extension, the tree should be sexually mature and fruit-bearing once aged 20-30 years. Interestingly, this tree came to our attention this week because we found an unusual seed pod in the leaf litter.

This seedpod was found in the west floodplain under the Kentucky coffee-tree. Since the species is dioecious, that means our tree is female, but where is the male? How was it fertilized? The pod was cracked open and one seed was removed. It was in poor condition, so it was discarded.

Two more fruits were found. One is significantly larger.

The larger pod has one seed.

It's a large seed, mearsuing approximately one inch across.

The seed is round and dark brown.

As with the Yapuon holly (Ilex vomitoria), the Native American Indians of the Southeastern Woodlands are reputed to have consumed a tea made from the seeds of Gymnocladus dioica. The paucity of consumer goods in colonial times, being a major issues for homesteaders and travelers, there has been interest in this tree's seed since at least the late 18th century. Some people employed the Kentucky Coffee-Tree as a coffee-substitute up to and possibly during the American Civil War, when a Union blockade cut off the Confederate States of America from international trade. It was greatly inferior to the alternatives, such as chicory and scorched barley, as an uncaffeinated coffee substitute. Experiments performed by John P. Spaeth and John W. Thieret in the earlier 2000s showed that although potable, this drink was generally squalid. While true coffee addicts would consider such a product little better than a criminal act, a hot herbal beverage is better than nothing on cold days and long nights. Let's now check out the specimen itself.

The Kentucky coffee-tree is pictured center. It grows in a heavily shaded floodplain. All lower branches have been removed, so it will easily be missed as "just another tree" unless one is looking for it.

The wish-bone shape of this tree is no doubt a response to growing in heavily-shaded conditions. This tree is clearly adaptable.

It was planted near a Pinus taeda, an on-site native. From its first planting in the arboretum, the Kentucky coffee-tree has had to compete for sunlight, leaning away from the looming pine tree. Alas, it's good to have friends, even if you have to share your place in the sun. These trees have known each other for a long time.

The photos below were taken during the winter months. They allow us a less-cluttered view of the landscape.

 Clumps of spiderwort (Tradescantia ohiensis) grow at the base of the Kentucky coffee-tree trunk. Spiderwort was planted at the same time as the coffee-tree.

Kentucky coffee-tree has gorgeous papery bark.

 

The tree has an irregular growth pattern, as noted above. Hopefully this will not lead to cracking and breaking in the future.

Additional resources:

USDA Plant Profile on Kentucky Coffee-Tree

Lady Bird Johnson Wildflower Center

North Caroline Gardner Extension