Tree of the Week: Water Locust (Gleditsia aquatica)

 

There is currently one water locust (Gleditsia aquatica) in the arboretum collection. Next week, that number might be zero. So go check it out while you can!

You can find our water locust in the middle of the arboretum. This nearly 30-year-old specimen stands on the south side of the long white wooden bridge that runs between the Student Union Building and Mickle Hall. It is pictured center, leaning to the left. But has it always leaned this much?

Nope! Consulting the photographic record, we see a fairly straight trunk, especially compared with the current state. This picture was taken on February 2, 2018. For comparison, note the lack of movement in the large tree behind it. You can see more pictures from that photoshoot on an old blog post, found here.

So, if the tree is leaning, what's going on at the base of the trunk? In order to answer this question, we need to be able to see the base of the trunk! During the summer months, the overwhelming mosquito population dissuades human activity in this wet area, so it's largely left unto itself, resulting in a thick mat of vines, mostly dewberry, but also Carolina moonseed, covering the ground. These vines and a few small trees had to be pulled away from the water locust so that we could examine the trunk.

Pulling weeds from around the base of this tree is no easy task; you can't drop your guard around this one. 

Not only is the trunk armed, but these spines, like natural caltrops, fall off and litter the ground around the trunk.

On this individual, most of the spines are located further up the trunk.

With the vines removed, we can appreciate the cypress knees that have grown up around the water locust.

We allowed a couple of laurel cherry trees (Prunus caroliniana) to remain, as something will need to fill the gap left by the removal of our water locust. The laurel cherry trees might as well have a chance at success since they are already here.

Looking at the base of the trunk, we see that the bark has rotted. There is an obvious breaking-away from the ground, which doesn't give us confidence in the tree's strength to remain standing for much longer.

 

Looking further up the trunk, we see a lot of blue sky. The remaining branches are scraggly and concentrated on one side of the tree.

Way up top, we see locust leaves. So, this tree is certainly alive, and perhaps it could go on living in this condition for some time to come. However, since it's located in the center of the arboretum, a relatively high traffic area, our only water locust must go. In recent years, water locust seedlings have been spotted in the surrounding area, so hopefully we can identify and preserve another one in the following months.