By Steve Roark

Contributing Writer

 

You don’t realize it, but when you look at our local mountains you aren’t really seeing the mountains themselves because they are covered in trees with a whole lot of leaves. On average a mature tree has a hundred thousand leaves. It takes around seventy biggish trees to shade an acre of mountain forest, which doing the math comes to seven million leaves per acre. And since you are looking at perhaps a thousand acres of forest at a casual glance, that comes to…well you get the gist.

 

When it comes to trees, we live in a blessed place. There are more varieties of trees, shrubs, and vines here than anywhere in the world except maybe rain forests.  Each tree and shrub has its own unique leaf that, with a little practice, can be identified

 

The main feature to look for in leaf identification is shape.  There are star shapes (sweetgum, maples), heart shapes (redbud), fat round ones (dogwood), and long skinny ones (willow).  The most common shape is called “lanceolate” or spear shaped.  Beech, sourwood, and elm have it.  Some trees have complex shapes with finger-like extensions called “lobes” separated by spaces called “sinuses”.  Oaks and maples have these features.

 

Something else to look for is the leaf margin.  Some leaf edges are smooth, while others are “serrated” with saw-toothed edges. The tooth shape and size varies between different species.

 

Another key feature is whether the leaf is “simple”, made up of a single blade, or “compound”, made up of three or more “leaflets”.  The way to tell the difference is to see where the leaf stem attaches to a twig with bark and buds.  If the stem of a single leaf blade attaches to a barked twig, then it’s simple.  If the leaf stem is attached to a soft green “twig” with no bark, then it’s probably a leaflet of a compound leaf.  Everything from the barked twig out is technically a single leaf.  Black walnut has very long leaves over two feet in length and is made up of 15 to 25 leaflets.  All the hickories have a compound leaf with five to nine leaflets.  Other trees with compound leaves include ash, boxelder, buckeye, and black locust.

 

One other important feature to look for is whether the leaves attach to the barked twig in opposing pairs (called opposite branching), or singly (alternate branching). The most common trees in our area with opposite branching are ash, boxelder, buckeye, dogwood, and maples.

 

The best way to learn tree leaves is to invest in a good reference book and start observing leaves out in the woods.   A good book is the “Field Guide to Trees of the Eastern US,” published by the Audubon Society. It has good color photos of leaves and breaks their identification down by shape, leaf margins, etc. It’s available at most bookstores.