Tree News

Easy Tree ID

You are driving along Pennsylvania highways and notice a scattering of small to medium size trees with the leaves turning brown in July or early August. What's going on here?

There is a very good chance that you are seeing the black locust (Robinia pseudoacacia). Our common locust is frequently spotted in abandoned farm areas and in scattered strips bordering highways. The dark leaves are caused by the locust leafminer (Ondotota dorsalis). The damage is generally uglier than it is desctructive.

I will soon have a complete profile on Robinia pseudoacacia in the Tree Profiles feature.

When you head into the woods across most of Pennsylvania and find a tree with opposite leaves, it is most likely a maple or an ash. If the leaves are simple, it would be a maple and, if compound, an ash. There are exceptions to this rule, and in future posts I will cover those exceptions (buckeyes and catalpas).

I offer the comparison of ash and maple tree leaves as a demonstration of how easy it can be to start mastering tree identification. It is only a first step, but I think you will be pleasantly surprised with your increased level of awareness with respect to trees if you start with that tidbit.

I think the most effective and fun way to identify trees is to begin by learning some general distinguishing features of groups and families of trees.  You can, of course, identify a tree with a good taxonomic key, but then you will have only learned a single tree (I will, of course, discuss using keys later and recommend quality field guides that include comprehensive taxonomic keys).