Big-Leaf Magnolia (Magnolia macrophylla)

The big-leaf magnolia (Magnolia macrophylla) is blooming this week.

The trunk and branches are spindly. The leaves and flowers are big! You will need to gently pull the leaves down to get a better look at the beautiful flower.

Flowers petals are long, large and droopy.

The flowers are brilliantly white, but for a short while. It seems like this flower lasted only a single day before yellowing. There are more buds higher up, but a ladder would be necessary for studying the flowers, as the leaves mostly obscure the blooms.

Dewberry Picking in the Arboretum

At the end of April, dewberry (Rubus trivialis) fruits are ripening in northwest Louisiana. Dewberry is a weedy plant―it readily germinates and thrives in unmanicured areas, such as along roadsides or fencelines. It also volunteers in areas where gardeners don't want it. This makes dewberry a classic "nuisance plant" because it spreads rapidly and the vines are covered with prickles. However, this time of year, it can be a joy to find: the wild, black fruits are a lightly-sweet, flavorful snack. 

Dewberry vines volunteer all over the Centenary College campus. Most are unwanted, and they are pulled up or chopped down. In the arboretum, there are more than a few cultivated patches, and there is one really big uncultivated patch. Near the Student Union Building, we have a mini-wilderness area that has developed into one large dewberry patch. 

On Saturday morning, two arboretum guests, a brother and sister duo, sampled and collected dewberries along the edge of the volunteer recruitment zone.

Dewberry wasn't planted in this spot; it volunteered here and has thoroughly entwined itself among the trees and shrubs. 

 

These young people were able to quickly identify the fruits and pick them. Neither individual complained about the prickles—the fruits often appear above the vines, making it easy to collect the fruits without being harmed by the vine's armor. Having small hands with deft fingers and being closer to the ground are advantageous!

 

Not all of the fruits are ripe at the same moment. Fruits in this patch have been ripening for nearly a week.

The dark black fruit is ripe and ready to be picked.

The red fruits are very pretty, but these aren't ripe. Let those develop on the vine another day.

Brother and sister picked three cups of dewberries in about 20 minutes, and then moved on to investigate other areas of the arboretum. That's $45/hr worth of fruit. Not bad!

Mexican Plum (Prunus mexicana)

We've added another Mexican plum (Prunus mexicana) to the arboretum catalogue. This species is a fan favorite, producing delectable and highly-colored fruits that make a complete mess during their season. Squirrels eat them; bugs eat them; we eat them. Raccoons and possums eat them after hours when nobody is looking. The mature trees produce so much fruit that it simply lays about on the ground. This time of year, if you look under any of those trees, you will find seedlings. The individual pictured below is one such seedling.

Last April, this young tree was collected from under the mature Mexican plum growing on the steep slope near Mickle Hall (see here). It survived transplanting and the long hot summer months thanks to an onerous watering regime. Today, it is almost a foot tall.

Since the fresh green leaves developed in full sun, we don't need to worry about shocking it with too much sunlight when we plant it.

We planted it in full sun near the top of a gradual slope on the north side of the Cline Hall dormitory. This is an open, grassy area, and this time of year we allow the wildflowers to grow tall. The stakes with pink tape are necessary for calling attention to our small tree—we don't want it to be stepped on, stomped flat, or mowed over.

Red Buckeye (Aesculus pavia)

On October 25, 2023, first-year students collected and planted seeds from red buckeyes in the arboretum. Approximately a month later, seedlings emerged from the dirt. Now, 16 months later, we see the first flowers! That's fast development.

Professor Rachel Johnson brought two groups of students to the arboretum for tours. The first group was from an 8 a.m. class. Students picked up 5 seeds and planted them in this spot, marked by the metal tag.

At minimum, three of the five seeds germinated. One plant remains, and it is short and wide, and it has one red panicle. 

This is full sun. Online literature says that red buckeyes can grow in full sun or shade, so this is one of our experimental spots for full sun conditions. The majority of our other buckeyes grow in part or full shade.

Students from Professor Johnson's noon class also planted 5 seeds. They were slower to germinate by just a week or two. Several seedlings emerged, and died back, and started again.

Today, we see two little plants. One is significantly larger than the other and it has one red panicle.

The arboretum has a steadily growing collection of red buckeyes. We are really hoping to draw in the ruby-throated hummingbirds with these clusters of pretty red flowers.

You can read more about the germination project on an earlier post, found here.

 

Winged Elm (Ulmus alata)

Today we added a young winged elm (Ulmus alata) to the arboretum collection. This species grows abundantly in Caddo Parish—it is very 'weedy'. There are three mature winged elms in the arboretum: one is an on-site native; one was intentionally collected from Walter B. Jacobs Nature Park in Caddo Parish; and one is a volunteer. Our new recruit was planted in full sun near Mickle Hall, and it is expected to flourish with very little maintenance.

This specimen was collected in Caddo Parish, just north of Shreveport. Discovered in 2023, after it had germinated in a pot of soil meant for another plant, it now enters the Centenary campus as a 2-year-old, measuring 18 inches tall.

Our little tree has already leafed-out. We see serrate leaf margins.

And looking closer, we see a slight ridge along the stem. This young tree is developing its corky 'wings', which help us identify this tree as a 'winged' elm. Sweet gum trees (Liquidambar styraciflua) also have this characteristic.

 

 

US Forest Service Ulmus alata Fact Sheet 

Bois D'arc (Maclura pomifera)

Three bois d'arc trees were planted on campus today. All are about a year old, and the tallest is approximately a foot high. You can read about the earlier stage of this project here, where we describe the collection and germination process.

We have three pots of bois d'arc (Maclura pomifera). Each pot has one main sapling, and there are several smaller saplings in each pot that will need to be trimmed back routinely until their roots die. We had such a high germination rate that we are now having to cut back seedlings that we do not have space for.

Our tallest sapling measures a foot high.

We already see new leaves on these young trees. You can also see a couple of thorns along the stem. 

We planted all three trees on the slope between the Student Union Building and Rotary Hall. They were sited along the southern side of the drainage channel. There is typically a small amount of water in this channel, year-round, so we are confident that the bois d'arc trees will find this to be one of the likeliest locations in the arboretum for their future success. Naturally, they will require frequent supplemental watering during their first summer, as they are not yet established.

A cottonwood (Populus deltoides) has thrived nearby. These trees ought to be great friends and get along splendidly, but there is surprisingly very little reference on the internet to them growing together. This must be due to the restricted natural range of the bois d'arc, which historically prevented it from colonizing all those areas suited to it. Self-described "desert rat" Gary Nored mentions on his blog that creekbeds in west Texas, along the US-Mexico border, are habitats for cottonwood and bois d'arc. Locally, we see mature bois d'arc and cottonwood growing together along the Clyde Fant Parkway. So, our bois d'arc saplings ought to do just fine.

In this photo, we are looking down the same slope, into the arboretum. A cottonwood is pictured at the far right edge of the frame. Our saplings are already planted, but they do not stand out in the landscape because of their small size. However, they are carefully marked with protective posts, and they will most likely grow quickly, making themselves more conspicuous.

 

Shortleaf Pine (Pinus echinata)

 

There is one shortleaf pine (Pinus echinata) in the arboretum collection. It is approximately 30 years old. In October 1997, two trees were purchased from Coyote Creek Nursery in southeast Louisiana. The following month, they were planted near the Student Union Building. Today, one tree remains.

The shortleaf pine is pictured center. It grows next to the sidewalk that runs between the Student Union Building and Cline Hall Dormitory.

The thin, flat plates on the trunk have a reddish tint.

And here we see the work of the yellow-bellied sap sucker (Sphyrapicus varius). There is a fairly straight, diagonal line of holes drilled across the trunk. At least the holes aren't actively weeping.

All of the limbs on the west side of the trunk have detached and falled off, presumably because they were heavily shaded by the nearby water oak (Quercus  nigra). The remaining lower limbs hang toward the open sidewalk, in full sun. 

Luckily this tree still has lower branches so that we can examine fresh spring-time twigs. Here we see reproductive activity. Shortleaf pines are monoecious, which means they have both male and female parts on the same tree. In this photo, we see a cluster of the pollen-producing catkins, and they are not open yet.

This twig was snipped without the aid of a ladder.

Shortleaf can be identified by the "short" needles that typically come in duos.

These needles measure less than 3 inches. By comparison, our loblolly (Pinus taeda) needles measure 7 inches long, and loblolly pines have three needles per bundle. 

Needles were removed so we could examine the catkins. According to Dr. Becky Barlow at Auburn University, catkins form in the spring while cones develop a few months later, higher in the tree. Catkins are a yearly product, while cones take two years to develop. A healthy, mature tree will therefore have staggered cohorts of pollen and cones.

At the current time, the catkins measure less than half an inch long. They will grow larger before releasing pollen.

USDA NRCS page on Shortleaf Pine

USDA Forest Service Southern Research documentation 

NC State University Gardener Page on Shortleaf Pine

The Shortleaf Pine Initiative