Indiana Leaf Identification

Look closely at a leaf's features to identify Indiana leaves.

Indiana is home to a variety of trees. It is estimated that more than 85 types of trees grow in the state, primarily hardwood trees with deciduous leaves. Identifying the leaves of a tree is one of the quickest ways to identify the tree. Do this by looking closely at the features of the leaf.

Leaf Structure

A leaf is comprised of separate parts that make up its entire structure. Knowing the names of these parts will help you in identifying the leaf. "Blade" refer to the entire leaf unit. The "apex" is the tip of the leaf, and the "base" is the part of the leaf that connects to the stem. "Veins" run through the leaf in a pattern; some leaves are "net-veined," for instance, while others have "parallel" veins. The "petiole" refers to the part of the leaf that connects it to the stem, and the collection of tiny leaves at the base of the petiole is called the "stipole."

Arrangement on Stem

When looking at the leaves, consider how they are attached to the plant. A single leaf attached to one node on a stem that alternates from side to side with other leaves is an "alternate" leaf arrangement. American elms have this pattern, as do American beech. An "opposite" leaf arrangement has two leaves attached at the same node, such as is found in the horse chestnut.

Simple or Compound

Leaves are classified as "simple" or "compound." A simple leaf has only one blade, and may or may not have a stalk or petiole. Examples of trees in Indiana that have simple leaves include red maple and American beech. Leaves are "compound" when they have more than one blade and may also have a complex stalk structure consisting of leaflets attached to the stalk. "Palmately compound" leaves, such as those on the horse chestnut, have 3 or more leaves attached at the end of the stalk. "Pinnately compound" leaves have a number of leaflets along a central stalk. Black ash is an example of a pinnately compound leaf.

Shape

The shape of the leaf is a key element in identifying it. "Elliptic" leaves, such as those on the American beech, are wider at the center and taper to tips of equal width. "Ovate" leaves are shaped like an egg--broader at the base than the apex. American elm and river birch are examples of trees that grow in Indiana that have ovate leaves.

Margins

The edge of the leaf--the "margin"--can have either a smooth edge or a serrated edge. Smooth-edged margins are called "entire." Dogwood is an example of a tree with entire margins. Serrated edges are called "toothed." The teeth may vary in number and size. The Siberian elm, for example, is singly toothed, while the black cherry leaf has saw-toothed margins. Margins may also be lobed, such as those on the leaves of red maple and black oak leaves.

References

• The Nature Conservancy in Indiana: Winter Tree identication
• Indiana University-Purdue University Fort Wayne: Native Indiana Trees
• University of Oregon: Plant Idnetification: Examining Leaves