Montezuma Bald Cypress (Taxodium mucronatum)

The genus Taxodium has three living members. First and greatest is T. distichum, our famous bald cypress, which is found up and down the Mississippi embayment, the Gulf Coast, and the Atlantic seaboard from Delaware to Miami. Less well-known is T. ascendens, the pond cypress, which has a similar but much reduced range. Finally there is T. mucronatum, the Montezuma bald cypress, whose native range is mostly within Mexico and Central America, although a few of the Texas counties on the Rio Grande are counted as well.

Consequently, the Montezuma bald cypress isn't native to Louisiana or the southeastern United States. But having all three Taxodium species in the arboretum allows any visitor to see for themselves the dissimilarities that exist within this one genus.

There are two Montezuma bald cypresses in the arboretum collection. Way back in the '80s, Professor Leuck purchased their predecessors from Woodlanders Nursery (Aiken, SC), and he planted them in his yard on Albany Avenue in Shreveport. In 1994, Professor Leuck collected and rooted two cuttings from the Albany Avenue property, and in the fall of 1995, he planted the new trees on the periphery of the arboretum, near the lower level entrance to the Student Union Building.

The Montezuma bald cypresses are tucked in between the two staircases, flanking the doorway. Today, this is the entrance to the Post Office. Thirty years ago in 1995, it was the entrance to the campus bookstore. These trees have witnessed a great deal of change.

 

On the left side of the doorway, we see the southern-most tree. Its trunk is noticeably thicker.

 

On the right side of the doorway, we see the northern-most tree. Its trunk has a smaller diameter. Given that these trees are growing far north of their native zone, maybe its microclimate exposure to colder weather makes this the slower-growing specimen.

The staircase provides a neat vantage point, and it also allows us to see the leaves up close. Over the years, the lower limbs of the cypresses were removed so that pedestrians could easily move about without ducking all of those branches.

The soft, feather-like needles are arranged either in an alternate or spiralling pattern. The needles are mostly evergreen under good conditions, lasting until spring when they drop to make way for new growth.

Here we see approximately 40 pairs of needles on one branchlet. Unfortunately the number of needles varies quite a bit and isn't particularly diagnostic between species. The small blunted tips of each needle gave rise to the binomial species name; mucronatum refers to an abruptly angled point.

The southernmost tree has the thicker trunk, potentially because it has access to more sunlight. Its trunk has fewer lower limbs.

The trunk with the smaller diameter has more lower limbs. 

An additional photo, showing the relative heights of the two trees, would be useful here. Perhaps the thinner-trunked tree is taller. And we forgot something else! In the future we need to add photos of these trees' cypress knees... just kidding! They don't have any. This is typical of Taxodium mucronatum, and the absence of knees on a cypress should set off alarm bells that one isn't dealing with the typical bald cypress.

 

 Useful external links

US Forest Service page on T. mucronatum 

USDA Plant Database profile on T. mucronatum 

Post Oak (Quercus stellata)

 

Storm winds shook the trees of the arboretum last week, rustling branches and scattering loose twigs onto the ground. Although messy, this provides us with ample opportunity to study and compare a broad sample of leaves. Our big old mature trees tend to drop only their lower branches, leaving their fresh summer-time foliage out of reach. One such specimen is the aged post oak (Quercus stellata) standing near the Student Union Building. Its gnarly branches are way up high, but this week some of those upper story leaves were knocked out of the canopy.

From the ground, there were a lot of nice leaves to sort through. We see variations in size and shape, but the general shape description runs the same: roughly cross-shaped with five lobes. Although, does anyone else get the feeling that these leaves are reaching out for hugs?

This photo aptly captures one prominent quality of the leaf surface: shininess! With the leaves laying flat on the pavement, sunlight bounces off the leaf surface.

Standing the leaf up against the wet bricks takes away some of the shine.

Irregular leaves make tree identification difficult. But, if you already know that it's a post oak, you can appreciate the irregularity, and say, "Hey, that's an interesting shape! Cool."

An irregular, but still more-or-less recognizable, post oak leaf

Passionflower in the Arboretum

Every year, Hummingbird Central puts out a map where users can report their first sightings of migratory hummingbirds. Let's play a similar game. Have you seen any Gulf fritillaries (Agraulis vanillae) yet? At the arboretum, we're still waiting on them. This year, the arboretum has two species of passionflower for the caterpillars to enjoy. 

Yellow passionflower (Passiflora lutea) can be found throughout the arboretum. It isn't cultivated in any particular spot and volunteers freely. Sometimes we have to pull it off other plants, and sometimes we allow it to climb and twine. This time of year, its quirky little flowers are on display. In this photo, the passionflower vine is attached to a yaupon holly (Ilex vomitoria).

 Also, this summer, we have something extra special. Maypop!

 

Last year we planted Maypop (Passiflora incarnata), specifically during the spring of 2024. In this post from the autumn of 2023, we made clear our intent to do just that. It grew for a short time, but the Gulf fritillary caterpillars soon devoured all of the leaves, so the vine was not given the opportunity to climb or flower. Surprisingly, the plant wasn't killed by this premature defoliation; it started growing again this spring. And it is thriving! There are plenty of leaves for the caterpillars this year. The vine is attempting to climb an old eastern red cedar trunk.

In late July, we are seeing the peculiar "spaceship" flowers, and still no sign of the Gulf fritillary caterpillars. Perhaps these vines will even produce fruit this year. If you've never had maypop fruit, you've missed out on something special! Yum!

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.

Tree of the Week: Redwood (Sequoia sempervirens)

Officially, the Ed Leuck Louisiana Academic Arboretum is a place for trees and shrubs native to the southeastern United States. From its beginning, one of the primary goals for the arboretum was to plant young trees of the same species that were naturally growing on the college campus. As experimental plantings and for botanical interest, non-native species have been planted in small numbers. One such specimen is featured on the blog today: the redwood (Sequoia sempervirens), a tree native to north America, but certainly not the southeast. At this juncture in history, the redwood naturally grows in northern California, near the coast, and up into Oregon.

During the spring of 1990, Professor Ed Leuck obtained a redwood seedling from Forest Farm Nursery, located in Oregon. It wasn't planted in the ground until January 1996. That means this individual is more than 33 years old.

 

Professor Leuck chose a location on the periphery of the arboretum, in a triangle of grass at the eastern corner of the Student Union Building. The triangle is formed by two sidewalks and the Student Union Building driveway. The redwood is pictured center, partially obscuring the corner of the SUB. It has a straight trunk and it is significantly taller than the building. If you follow the trunk all the way up, you will see why this tree is of special concern this week.

 

The top of the redwood looks dead! What happened here!?! How long has it looked like this? Our forward looking gaze needs to turn upward more often.

The trunk hasn't shown any signs of distress. It's a thick, handsome trunk, growing next to a busy intersection of sidewalks. Typically, there are fresh green shoots near the base of the trunk. Today was no exception.

 

After the shoots were trimmed back, a white string was tied around the trunk, 3½ feet off the ground. At more than 33 years of age, this redwood measures 5 feet around. This species is known for rapid development, so its large size is no surprise.

The bark is reddish-brown, fuzzy, and furrowed. All of the lower limbs have been removed for sidewalk traffic, but upper limbs droop down to showcase pretty green foliage. Can you see a face on the trunk? Several lower branches were trimmed today to clear the sidewalks. The act of trimming branches creates a pleasant aroma in the air; leaves and branches are nicely fragrant, like citrus.

This is a short branch with numerous leaves. Redwood leaves are very small.

Leaves have a feathery appearance but aren't soft. Some of the leaves feel rubbery while others feel pointy.

 

It's summertime, by the way, season of the cicada.

 

Here we have 5 leaves, all narrow and less than an inch in length. All of these leaves were taken from the drooping lower branches. The leaves way up top are alleged to have a slightly different appearance. Of course, the leaves at the top of our redwood look dead!

 

Reading online sources about this species confirms the obvious: this non-native tree is out of its element. This redwood could tolerate the hot July weather if it also had some fog to help it replenish its water loss. For 20 years, this specimen thrived in the shadow of the Student Union Building, a nice micro-climate that helped it retain moisture. Now that the redwood has out-grown its sheltered environment, it is suffering. That's one explanation, at least, for the sudden unhappy appearance. 

The online literature also tells us that all hope is not lost. Redwoods have an amazing ability to re-sprout: if it loses its crown, it can grow another one! For now, we need to make sure this individual gets extra water during our late-July heatwave, and remember to look up more often. 

For information about this very interesting species, consult the following online sources:

U.S. Department of Agriculture, Forest Service, Southern Research Station

National Park Service 

Virginia Tech

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 Removal: Box Elder Maple (Acer negundo)

 

This week we say goodbye to a box elder maple (Acer negundo). We do not know the age of this tree. It was a volunteer, and when it entered the catalogue, an approximate age was not given.

 

This tree has been tagged for removal since spring 2020, after it suffered significant storm damage. You can read about it and see pictures of the storm damage here. In the above photo, we see a thick, straight trunk and dense foliage up top. It's clearly alive.

Up close and personal, it's truly awful.

Here we see fungal growth, mold, missing bark, and insect damage.

This is extensive, running across half the circumference.

At about four feet up the trunk, the tree had a circumference of 30 inches.

The first step in removal is to take off lower branches.

Then the crown and all the other branches were removed, leaving only the trunk.

The trunk was taken down in one piece.

There was an entire ant civilization living in the caverns of this tree, fifteen feet off the ground. Luckily they could only bite and not sting with venom.

After stump removal, there's not much evidence of this tree's relatively short life. Its memory will be preserved on this blog and our records.

Tree of the Week: Nuttall Oak (Quercus texana)

Our Nuttall oak (Quercus texana syn. Q. nuttallii) has a recorded history of high acorn production. You can read about it on an old blog post, found here. This year, acorn watch 2022, we see, especially by comparison, an exceptionally high number of Nuttall oak acorns. This specimen is especially valuable as germplasm because it is a local genotype.

 

This Nuttall oak grows in a low spot, at the bottom of a gradual slope, near the campus Fitness Center. At four feet off the ground, the thick trunk has a circumference of sixty-two inches. As we can see, all of the lower branches have been removed.

 

 

This tree grows at the conjunction of two sidewalks. Because of its proximity to foot traffic, this Nuttall oak has endured much pruning over the years. The large circle in the center of the trunk is where a large limb was removed.

 

Large, circular scars can be found further up the trunk as well.

 

 

We see smaller circles, too.

 

 

Note the prominent surface roots, reminiscent of live oaks. Keep this one away from important sub-surface infrastructure.

 

 

Note the serpentine curling.

 

These are quite handsome. Don't you think a bonsai enthusiast would enjoy it?

 

 

 

Although mostly obscured by the thick foliage, numerous clusters of developing acorns can be found if you go looking for them. These acorns were photographed without the aid of a ladder―although the lower branches have been removed from the trunk, the upper branches droop down.

 

More cap than corn at this stage.

 

Here we can appreciate the two different sizes of acorns. There are two different sizes because they take nearly two years to develop. The larger acorns will ripen this fall/winter, while the smaller ones will ripen in 2023

 

 

Thankfully for the purposes of our acorn project, two twigs needed to be trimmed from the drooping branches. They incidentally had several acorns attached to them.

 

 

Here we see mostly the larger but still immature acorns. One smaller acorn, on the middle of the bottom row, will ripen in 2023 if it hangs on until then.