Tree Removal: Pawpaw, Sweetgum, Mulberry

Today we continued normal cleanup operations in the Arboretum. This customarily involves cleaning up the paths, picking up fallen limbs, moving gravel around, and today a special task: cutting down some trees and removing stumps.

First, a water leak in the arboretum, down the slope from Mickle Hall, required a lot of dirt work. This area is in shambles, but there is really no alternative. Our native clay can be quite an adversary. Don't try to walk through this area; just go around.

Onto the main tasks.... Here is a sweetgum (Liquidambar styraciflua) stump, which you can see on an earlier blogpost here. In that post we said "Now all that remains is a two-foot stump which will be removed at a later date." That day has arrived.

Resprouting, this tree is still alive. This photo was taken after all of the new growth was trimmed.

Afterwards, we have a more-or-less flat area that will not be a tripping hazard. The roots were not removed, which means that we have not yet seen the end of sweetgum shoots.

Next we have a highly suspect pawpaw (Asimina triloba), which you can read more about on an earlier blog post, here. This tree has had a broken crown for nearly a decade, which may have led to some health problems. Recently it has taken a turn for the worst, so now we must make an assessment. Before we cut the tree down, let's inspect the specimen to determine its condition.

 

The bare pawpaw trunk is pictured center. Louisiana palmettos and titi shrubs are in the background.

This image becomes more unsettling the longer you look at it. Here you can see fungal pink slime oozing from the bark and forming bubbles. What on earth is this?

This rotten branch nub was characteristic of the whole tree.

Scoring thin bark will often reveal healthy green cambium underneath. Scoring this pawpaw revealed dead tissue and only excited the ants and other bugs crawling across it. Snapping a few twigs, which should have been green and springy, verified that this tree is completely dead. Cutting it down released a horrendous mushroom-like smell.

All gone, and only a few blog posts to tell the tale.

This cross section reveals a rotten tree. It may not be immediately obvious from this photo, but the inner rings of the tree were sickly green and oozed.

The lower feet of the trunk served as a nursery for untold billions of fungal spores and the entire surface of the bark had turned green. The white specks were tubular filaments rising off the surface of the bark and ending in a nodule.

Finally, this undesirable specimen is a hybrid of Morus rubra, the red mulberry, and an Asian species. Since we want to preserve native species, we will remove this one as we have removed other white-berried and black-berried mulberries in the arboretum.

We see leaves of the characteristically variable Morus genus.

Our mulberry hybrid was dissassembled.

This area is already a major tripping hazard due to holes and uneven ground, so we've sawed the stump down as low as possible. Cutting around soil will quickly dull your chainsaw blade, but there's no helping it.

Autumn is a great time of the year for these kinds of clean-up operations. Look around and you'll find plenty of work to do!

Mulberries and Dewberries

In the arboretum, you can find several large patches of dewberry (Rubus trivialis). This is such a weedy plant; it volunteers across campus. Only a few patches are officially in the arboretum catalogue.

Dewberries turn black when they are ready to eat. They aren't sweet, but they are wonderful in fruit smoothies.

The little black fruits are numerous, just be careful when picking them, as the vine is covered in prickles. Ouch!

In the arboretum, you can find mulberries (Morus rubra) in one location: on the grassy slope north of Cline Hall dormitory. There are three trees currently producing fruit. Like the dewberry, the mulberry turns black when it ripens.

 

New Recruits

We have four additions to the arboretum catalogue. All four plants are less than a year old. This past spring, they germinated in a large pot at a homeplace north of Shreveport. The pot was, at the time, meant for a satsuma tree. Oak acorns collected from the Centenary Campus were intentionally planted along with the satsuma, so that might explain the oak seedling that was found in the pot, but the other three seedlings volunteered and were allowed to grow in the pot over the course of the summer. On Wednesday, the four young trees were removed from the satsuma pot and transplanted into the arboretum.

 

A black cherry (Prunus serotina) was planted at the top of a slope, in full sun, at the southwest corner of the arboretum. It measures 2 feet, 1½ inches.

 

At the bottom of the same slope, in a sea of oak leaves, a leafless redbud (Cercis canadensis) was planted. The metal stakes marked with pink tape are absolutely necessary for protecting such an inconspicuous tree. It's the tallest individual planted, measuring 2 feet, 7½ inches.

Taking a closer look at the redbud, we see the characteristic zig-zag stem.

Across the sidewalk, closer to the Fitness Center, a red mulberry (Morus rubra) was planted. There are two red mulberry trees growing in full sun toward the top of the slope, so now we will see how the mulberry fares at the bottom, with more moisture.

 

Our red mulberry is 1 foot tall.

 

Lastly, we have a species of oak tree (Quercus sp.). This little tree, only 6 inches tall, was planted toward the top of the grassy slope on the north side of Cline Hall, not too far from the black cherry. We are hoping that this individual is a southern red oak (Quercus falcata). In the fall of 2022, acorns were collected from a mature southern red oak, growing on the Centenary Campus, near the intersection of Kings Highway and Centenary Boulevard. The acorns were planted in the satsuma pot, and in the spring, this oak sprouted, but its leaves do not resemble the leaves of the southern red oak from which acorns were collected. So, what are we to think?

Now, would you say that this oak leaf resembles a duck foot print? If so, then there is no reason to doubt that this is a southern red oak. The experts at LSU explain that, "...leaves of seedlings and saplings typically lack lateral lobes, and have only a few shallow terminal lobes and blade shape that is broadest near the apex, resembling a duck foot print" (Louisiana Plant Identification and Interactive Virtual Tours). At minimum, we must conclude that leaves from a mature tree and leaves from a seedling differ in appearance, so we should be hopeful. But, for now, we will error on the side of caution and tag this individual as Quercus sp.

New Recruits

 We have three new recruits for the arboretum catalogue. These three young plants were collected from the grounds of the arboretum and then transplanted to their current locations. All can be found on the grassy slope near Cline Hall dormitory. This area is currently a full-sun location. Within the next decade we hope to have more tree leaves and less sun.

 

This little rusty blackhaw (Viburnum rufidulum) was found growing between the two old persimmons.

 

Hopefully this mulberry is a red mulberry (Morus rubra), and not a hybrid. Only time will tell. It was collected from under the groundsel bush (Baccharis halimifolia), also located on the grassy slope near Cline Hall.

 

Also under the groundsel bush, a very small fringe tree (Chionanthus virginicus) was found.

 

Tree of the Week: Red Mulberry (Morus rubra)

We have a young red mulberry (Morus rubra) that deserves a mention this week. It's a small tree with slender, waving branches, and this week, all of the branches are covered in little berries. The tree was planted as a bare root sapling in the spring of 2013, making the tree at least 6 years old. For such a young tree, it is producing a lot of berries! You can find this specimen on the sunny, grassy slope north of Cline Hall. Help yourself to a few berries, but make sure you get the ripe (black) ones!

This fruiting red mulberry is growing in full sun, on a gradual slope, in clay soil. Thus far, no fertilizers have been used. During the long, hot summers, this area is soaked at least once a week by way of the in-ground irrigation system.

The primrose volunteered here, and we have been cultivating it around the trunk of the red mulberry.

The ripening berries appear alongside the new, yellow-green leaves.

We are seeing a lot of berries!

These berries aren't quite ripe yet. Wait until they turn black.

The berries are approximately half an inch long. They are similar to the blackberries you find in the grocery store and also the wild, native dewberry. The red mulberry is the queen of our native fruits.

The ripening dewberries are almost indistinguishable from the mulberries. The berry on the far left was collected from a dewberry patch, while the three berries on the right are mulberries. If you have the space, plant a a morus rubra and enjoy!

Tree of the Week: Red Mulberry (Morus rubra)

Berry production is underway on the grassy slope north of Cline Hall. The arboretum's two red mulberry trees are producing tasty black berries, and the branches of the two young trees are still low enough to the ground to make for an easy harvest. These two trees were purchased in the spring of 2013, at the Sabine Soil and Water Conservation District tree sale in Ringgold, Louisiana, and were planted directly in the ground the same season. Both trees are healthy, but one is clearly outshining the other, growing taller and producing more berries. The more successful tree has less competition for sun and water.

The more successful of the two trees has less competition, planted away from any big trees and near a good sprinkler.

The root system of this mulberry is competing with an elderly white oak (Quercus alba).

Ripening fruit

The ripe berry resembles a blackberry

Cluster of berries on the more successful tree

While documenting the progress of these two red mulberries, the arboretum's older mulberry tree was examined. Approximately 10 years ago a mulberry volunteered in the drainage of the arboretum, becoming a very healthy shade tree. This tree is also fruiting, but unlike the specimens shown above, these berries are white. This suggests that our volunteer is a white mulberry (Morus alba) or a hybrid, which is an invasive non-native species. If further research shows this specimen to be an invasive white mulberry, the tree will be removed.

White berries on the volunteer mulberry tree (possibly Morus alba or mulberry hybrid)

For more information about the red mulberry consult the following:
United States Department of Agriculture
The Morton Arboretum
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)