How to Identify a Tree Using Leaf Shape, Margin, and Venation

Botanists and foresters have developed terms for the patterns and shapes used in tree identification. Some tree species make things more interesting by displaying more than one type of leaf structure. Other species leaves make it nearly impossible to misidentify them because each leaf is unique. Trees with unique leaves include ginkgo, sassafras, yellow poplar, and mulberry.

All tree leaves have an outer layer called the epidermis which can be used in the identification process. This leaf "skin" always has a waxy cover called the cuticle and varies in thickness. The epidermis may or may not support leaf hairs, which can also be an important botanical identifier.

Leaf Shape and Arrangement

Leaf Shapes and Arrangements. Wikimedia Commons/derivative work: McSush

Studying leaf shape and the arrangement of leaves on a stem is the most common way of identifying a tree in the field during the growing season. The novice taxonomist usually starts with a tree leaf shape, which is determined by the presence or absence of lobes. One can often name the tree species without using any other identification marker.

One thing to remember is that a tree's leaves can also vary in shape according to their position on the tree, their age after budding, and the presence or absence of insect/disease damage. These variations are usually easy to deal with by finding a healthy specimen in its natural environment.

  • Leaf shape can vary considerably. The most common shapes include oval, truncate, elliptical, lancolate, and linear. Leaf tips and bases may also be unique, with names based on their shapes.
  • Leaf arrangement is mainly limited to two basic petiole attachments: simple and compound. Compound leaves are further described as pinnately, palmately, and doubly compound.

Leaf Edges or Margins

Leaf Margin. Wikimedia Commons/derivative work: McSush

All tree leaves exhibit margins (leaf blade edges) that are either serrated or smooth.

Leaf margins can be finely classified based on at least a dozen unique characteristics. There are four major classifications you need to know and into which all others will fit:

  • Entire Leaf: The margin is even and smooth around the entire leaf edge.
  • Toothed or Serrated Leaf: The margin has a series of toothlike pointed teeth around the entire leaf edge.
  • Lobed Leaf: The margin has an indention or indentions that go less than halfway to the leaf midrib or midline.
  • Parted Leaf: The margin has an indention or indentions that go more than halfway to the leaf midrib or midline.

Leaf Veins and Venation Patterns

Leaf Venation. Wikimedia Commons/derivative work: McSush

Leaves have unique structures, called veins, that transport liquids and nutrients to leaf cells. Veins also carry the products of photosynthesis back to the rest of the tree.

A tree leaf has several types of veins. The central one is called the midrib or midvein. Other veins connect to the midrib and have their own unique patterns.

Tree leaf veins in dicots (we also call these trees hardwoods or deciduous trees) are all considered to be net-veined or reticulate-veined. This means that the veins branch from the main rib and then sub-branch into finer veins.

There are two classifications you need to know for tree identification:

  • Pinnate Venation: The veins extend from the midrib to the leaf margin. Examples include oak and cherry leaves.
  • Palmate Venation: The veins radiate in a fan shape from the leaf petiole. Examples include maple and sweetgum leaves.