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.

 

Osage Orange; Bois D'arc (Maclura pomifera)

As the bois d'arc is a dioecious tree, the arboretum catalogue is somewhat incomplete. The specimen we currently possess is male, and while males are certainly necessary to perpetuate the survival of the species, we get no fruit from them. The unique green fruit is the most noteworthy feature of this species, something that we would like to show to the Aboretum's guests.

After last winter's ice storm, the arboretum curator discovered a decrepit, sad-looking bois d'arc on a fenceline in Caddo parish, just north of Shreveport. Surrounded by a grove of invasive bamboo, next to an impromptu trash dump, and near an unfriendly pack of local canines, this tree has been lost to the knowledge of mankind for decades. Its presence on a property line is fairly good evidence that it was intentionally planted there. The arboretum curator only recognized the tree as a bois d'arc due to the presence on the ground of a solitary green fruit. Considering the extensive rot and overall poor state of this tree, that may be the last fruit it ever produces. 

Two to three months of cold winter temperatures are necessary for the germination of bois d'arc seeds. We definitely had such temperatures this year. After being collected, the fruit was tossed onto the ground outside, where it sat for the duration of January, February, and March. By the end of March, the fruit was black-and-brown, soggy, and infested with a variety of nasty critters. The seeds were painstakingly extracted with a knife and a pair of tweezers, yielding approximately 100, with an estimated half that number being left behind. This was a messy job. The seeds were washed and allowed to dry, then placed in a bowl of rainwater to set for about a week. After this, they were planted five to a container in potting mix. A couple weeks later with temperatures rising, young bois d'arcs are beginning to push up through the potting mix! We are pleased to see that the old tree has produced viable seed. Providence willing, these specimens will become part of the arboretum collection.

We have a flat of seedlings. About five seeds are sprouting per day.

Here we can see one larger sprout and another which still has the seed coat attached, still covering the cotyledon.

The bois d'arc is pictured center. Almost every visible leaf is from poison ivy or another vine.

Here we can see a few sprouts coming off the trunk, a feeble last attempt to get ahold of some sunlight. The bamboo is winning.

From this side, we have a better look at the trunk and its branches. The tree was able to grow in this location long enough to develop a thick trunk. Unfortunately, it appears that the bambo has outcompeted it in recent years, but, luckily, we found one of its fruits and have thus far had success in our germination project.

Springtime Flowers

Bois d'arc flowers are not showy. Both male and female flowers are inconspicuous. This year, the bois d'arc flowers in the arboretum did not go unnoticed, but unfortunately the photographic lens caught them a little late. Below are a couple of pictures from the lone bois d'arc in the arboretum.

We appear to have a male bois d'arc. Oregon State University has a nice picture illustrating the difference between male and female flowers. You can find it here.

Tree of the Week: Bois D'arc (Maclura pomifera)

It's getting towards the end of July and northwest Louisiana is under a heat advisory. Its hot, hot, hot. What better time to talk about shade trees? The bois d'arc (Maclura pomifera) is largely known and recognized by its unusual fruit: a mostly inedible green, softball-sized syncarp. These drop to the ground in late summer and early fall. Although the fruit might not be edible, we can appreciate the great work these trees are doing to provide relief from the sun.

We have a solitary bois d'arc in the arboretum collection. In 2000, Ed Leuck collected bois d'arc fruit from East Kings Highway in Shreveport, quite close to Centenary's campus. Those seeds germinated in the campus greenhouse, and the most promising specimen was planted as a small tree in 2004. We presume it to be male, since it hasn't produced fruit. This species is dioecious, individual trees are either male or female, unlike many species of plants. The tree is doing so well, and the fruit of the species is so odd, that adding a female counterpart to the collection might be in order.

The Maclura pomifera in the arboretum collection is approximately 16 years old. It's a healthy tree, helping to shade the paths of the arboretum. All photos were taken at approximately 11 a.m., on a very hot, sunny July day.

Not much grows under this bois d'arc, probably because of the heavy shade and the slope of the hill. Unfortunately this creates an erosion problem, exposing tree roots. The orange root of the bois d'arc can be seen in the photo above.

The roots of the bois d'arc are characteristically orange.

Only a little light hits the ground under the bois d'arc. On the other side, the concrete sidewalk is brightly lit by the late morning sun.

Looking up, the branches of the bois d'arc jut out in every direction from the trunk, a much wilder display of branches when compared with last week's tree-of-the-week, Fagus grandifolia.

Branchlet of Maclura pomifera blocking the sun

The simple leaves of Maclura pomifera have an egg-like shape but are distinctly pointed at the tip.

When working near a bois d'arc tree, one must watch out for the thorns.

A young crossvine (Bignonia capreolata) climbs the trunk of Maclura pomifera.

You can find additional images of this tree here.

For more information about this species consult the following:
Louisiana Plant Identification and Interactive Virtual Tours
Texas Native Plants Database
United States Department of Agriculture

Maclura pomifera