This web site features the trees, shrubs and woody vines that are the subject of Ohio State University’s ENR 3321, Biology and Identification of Woody Plants. When completed, it will consist  of individual pages that describe each of the 60+ species covered in the course, and virtual field trips to the 5 study sites. 


The principal characteristics used to distinguish trees are features of their leaves. Who knew? First and foremost, we have LEAF ARRANGEMENT, which tells us how many leaves are attached at each NODE (i.e., the point along the stem where leaves are attached).

Leaf arrangement
left: alternate (hackberry). center: opposite (honeysuckle). right: whorled (buttonbush)

Another leafy distinction has to do with whether or not the leaf consists of a single unbroken blade, or if instead it’s fully and completely divided into separate leaflets. The set of traits is called LEAF COMPLEXITY, and comes in two general types: undivided leaves are termed “simple,” and the divided ones, “compound.” Compound leaves can either be pinnate (leaflets arranged along the leafstalk), palmate (all attached at the same point), trifoliolate (like poison-ivy) or twice compound (leaflets themselves divided into sub-leaflets).

Leaf complexity: is the leaf fully and completely divided into leaflets?
Maple has a simple (undivided) lead. Multiflora rose leaves are pinnately compound.
Buckeye has palmately compound leaves. Some climbing prairie roses have trifoliolate leaves (3 leaflets).

A third category of distinctions deals with the leaf margins.

Leaf margins can vary.
Entire leaf of dogwood. Singly serrate leaf of basswood.
Doubly serrate leaf of elm. Lobed leaf of oak.