Paw Paw (Asimina triloba)

Approaching the end of July, things are still looking green in the arboretum. Thus far, we have had an unexpectedly wet summer. We're around 8 inches in excess of our expected year-to-date precipitation (approximately 40 actual versus 32 expected) and we've had around 7 inches of rain since June 1st. That's enough to keep the frogs happy! New recruits in the arboretum are particularly thankful, one such specimen is pictured below:

This is a young paw paw (Asimina triloba). The young tree comes to us from the banks of the Missouri River in Nebraska, where it was collected by Mark Anderson. Mr. Anderson successfully germinated numerous seeds for a project on his Texas property and was kind enough to donate five plants to the arboretum. This past winter, we planted three paw paw saplings in the arboretum. One died, and one of the two survivors is shown in the photo. Since it's so easy for the weeds to overrun such a small individual, the regular application of elbow-grease (regular weed-pulling) is necessary, especially with all of the aforementioned summer rain. And after the weeds are removed, a layer of mulch must be added to the ground around the stem to prevent the dirt from drying out too fast.

Persimmon (Diospyros virginiana)

In October 2023, we identified and collected eight persimmon seeds from the Caney Lake district of Kisatchie National Forest in Webster Parish. The seeds were immediately planted in one big pot, and during the spring of 2024, they germinated. Seven seedlings grew vigorously in the same pot for approximately a year. 

This past spring, five of the saplings were planted in the arboretum, and two were set aside and repotted as a backup plan. Now that it's June, four out of the five saplings planted in the arboretum are alive, and one in particular looks great. The overall high germination rate and low mortality of these specimens shows how vigorously our native trees must fight for survival in wild conditions. Pampered and given every opportunity by helping human hands, they succeed easily.

This persimmon sapling grows in full sun toward the top of the grassy slope east of Rotary Hall. It is a year old. The trunk is very slender and wobbles under the weight of the big green leaves. Possums are eagerly awaiting the maturity of this tree, although it will be quite a few marsupial generations before any of them get a taste. Perhaps there's an old possum proverb: "The best time for an arboretum curator to plant a persimmon tree was ten generations ago."

Tulip Poplar (Liriodendron tulipifera)

Our little tulip poplar (Liriodendron tulipifera) is growing up nicely. In 2022, this individual volunteered on the north edge of the arboretum, down slope from mature tulip poplars. The following year it was extracted and relocated to a more suitable spot. 

 

In April 2023, the sapling was photographed against a black umbrella when it was less than 8 inches tall. Given that this species can grow to become one of the largest trees (over 100 feet) in Eastern North America, we have on record some modest beginnings.

                                     

Today, it looks healthy and appears to be living up to the expectation of being a 'fast-grower'. Pictured here in June 2025, we see that our tree has grown significantly. Based on photos from last December, it may have nearly doubled in height. The trunk exhibits a slight lean due to the  shade cast by a nearby swamp dogwood (Cornus foemina), but our tree has successfully outgrown that competition. Additional staking would be a prudent intervention to correct the current lean while the tree is still supple. In another decade it will be big enough to support numerous bees and moths with its leaves and nectar.

 

To see a post on the gorgeous fall colors offered by this specimen, click here. 

Summer Concerns; Irrigation in the Arboretum

Centenary College, "Where the sleepy, silver bayou, / Gleams among the pines...." The Alma Mater says that the campus once had a bayou. What happened to it? There are still a few big pine trees, but much has changed over the past hundred years. 

The growth of modern cities with their necessary infrastructure of concrete streets & sewerage has greatly altered local hydrology. Whereas in the past rains might saturate a richly developed soil, rainwater is now swiftly funneled across impermeable barriers of roof-and-road into storm sewers and drainage canals. For our purposes here this means that despite getting on average 50+ inches of rain per year, summer conditions can easily cause drought. Since we need to keep our wide array of arboretum species alive for academic purposes and keep the non-native grass alive for aesthetics, this means we need to supplement our natural precipitation with artificial irrigation, mostly in the form of sprinklers.

An in-ground network of pipes supplies well water to most of the arboretum, and much of that system can be programmed to run automatically. Some lines of irrigation must be manually turned on, and water hoses must be hauled and stretched to reach a few small patches.

The sprinkler system is an absolute necessity for maintaining the health of the arboretum. The fact that it can provide an amusing diversion is a nice side-benefit.

Laurel Cherry (Prunus caroliniana)

Last week on the blog we explained that, even though a tree looks pitiful and nearly dead, we shouldn't rush to cut it down and replace it. This week, we need to explain why a tree that looks beautifully green and productive needs to be cut down and replaced as soon as possible.  

 

A laurel cherry (Prunus caroliniana) is pictured center, completely blending in with its neighbors. On the right side of the frame, we see a non-decaying trunk of a deceased eastern red cedar (Juniperus virginiana) [read more about that individual here].

 

After removing the lower branches, we can now see the trunk of the laurel cherry. It is definitely leaning. 

It's leaning to the south. 

The southward leaning branches were heavy with leaves, and the fruits are numerous. 

Laurel cherry trees are handsome evergreen trees and the fruits ripen to blue. Keep in mind that this species is poisonous.

 

This is an interesting tree, and other than the lean, it appears to be healthy, so why cut it down? There are three reasons. First, the base of the trunk shows damage, which is a serious health concern. Second, there are several laurel cherry trees in the arboretum collection, and there are undocumented volunteers as well, so even if we cut this one tree down, the species will still have a strong presence in the arboretum. Finally, we have a young laurel cherry growing near the base of the trunk, so we can cut the big tree down and allow the young laurel cherry a chance to thrive. For these reasons, this richly green laurel cherry is on the docket for removal. 

 

In this photo, we see that the lower trunk of the laurel cherry is damaged. Also, on the left side of the frame, we can see the young laurel cherry ready to take its place. The young tree has grown up in 100% shade, so if we cut down the older tree all at once, it might be too much of a shock for the little one. So, for today, we started on the gradual process by removing all of the lower branches of the big tree. And in the following months we will steadily remove more branches, slowly exposing the smaller tree to more direct sunlight.

 

 

See previous posts on laurel cherry trees in 2023, and from early 2020 and late 2020.

 

Lady Bird Johnson page on Laurel Cherry 

USDA page on Laurel Cherry 

Scarlet Buckeye (Aesculus splendens)

The arboretum's only scarlet buckeye (Aesculus splendens) appears to be in its death throws. Leaves are absent and its limbs show evidence of decay, with patches of peeling bark. This tree was previously covered in a blogpost from 2021, and even earlier in a blogpost from 2018, alongside its old friend the peppervine (Ampelopsis arborea). Careful examination reveals some signs of life, but the outlook is grim.

This placard has weathered more than a few seasons. Our scarlet buckeye is, at minimum, 37 years old. It was purchased in 1988, from Woodlanders Nursery (Aiken, South Carolina).

 

You can find this tree on your right as you walk from the Fitness Center towards the Hargrove Bandshell.

 

We can see all the branches―they aren't concealed by leaves.

And up close the branches do not look good. Peeling bark opens the tree to attacks by insects and fungi, and it indicates internal deficiencies within the tree's health that make these problems more deadly.

 

A will to live is still present. Unfortunately, this tiny leaf is at the tip of a branch that already shows significant decay.

The trunk does not have any peeling bark.

And looking closely at the trunk, two green buds were found. This is one. Do you see it?

Zooming in on the trunk, we see new green growth.

 

This is the second green bud found on the trunk. Perhaps more will appear soon.

 

Although the prognosis is not good, the arboretum isn't a place to rush and cut a tree down―we're not in a hurry to determine the next step. Let's give the specimen a reprieve, and see what happens in the coming weeks.

Big-Leaf Magnolia (Magnolia macrophylla)

Last month, the big-leaf magnolia caught our eye with its large, drooping, creamy white flowers. On par with the American lotus (Nelumbo lutea) for the prize of "biggest flower native to North America," this rare specimen deserves more attention. We currently have three plantings of big-leaf magnolia in the collection, and all three would benefit from some spring-cleaning activities, like pruning and weeding. 

 

Two big-leaf magnolias are pictured here. There is a larger one in the center, and a smaller one is leaning on the right side of the frame. The smaller one was planted in 2009, while the larger one was planted a few years prior. Both were badly damaged in August 2020, during the storm winds from Hurricane Laura. In this photo, we see the work to be done: surrounding shrubs and vines are encroaching on the space allotted to the big-leaf magnolias.

We cut back wax myrtle (Myrica cerifera) shrubs to allow more sunlight for the magnolias. Virginia creeper (Parthenocissus quinquefolia), poison ivy (Toxicodendron radicans), and some grape (Vitis sp.) were all pulled from around the base of the skinny trunks. A few stalks of lizard tail (Saururus cernuus) were also snipped to increase signage visibility.

Despite being more than 15-years-old, these are still small trees, and they need help when it comes to competing with their more aggressive neighbors. And since this species isn't particularly robust, we are keeping both trees in the catalogue, rather than cutting down the smaller of the two. We don't want to cut the small tree for a couple of reasons: it doesn't take up much space, and it is our back-up plan or insurance policy if the larger tree dies. A falling widow-maker could easily cause such a fatality.