How to Identify a Tree by Its Leaves, Flowers, or Bark

Willows (Salix sp.), illustration
Parts of a Willow tree. DEA PICTURE LIBRARY / Getty Images

Trees come in various shapes and sizes but all have the same basic botanical parts and structure. Each tree has a central column called a trunk. The bark-covered trunk supports a framework of branches and twigs known as the tree's crown. Branches, in turn, are covered in leaves and sometimes flowers.

Each tree is anchored in the ground by a network of roots, which spread and grow thicker in proportion to the growth of the tree above the ground. In a mature tree, most of the cells of the trunk, roots, and branches are dead or inactive. New tissue growth takes place at only a few points on the tree, by the division of specialized cells. These actively growing areas are located at the tips of branches and roots and in a thin layer just inside the bark. Lastly, trees have reproductive structures: either flowers or cones.

All of this information can help you find the essential markers needed to identify a tree. Leaves, bark, twigs, and fruit can make quick work of tree identification.

Leaf Shape

green leaves natural background
Unggul Wicaksono / Getty Images

Leaves are the food factories of the tree. Powered by sunlight, the green substance in leaves, called chlorophyll, uses carbon dioxide and water to produce life-sustaining carbohydrates through the process of photosynthesis. Leaves are also responsible for respiration and transpiration.

A tree's leaves are one major marker that helps in identifying the species. Most trees can be identified by their leaves alone.

Leaves come in many different shapes and sizes. The "star" shape of sweetgum, for example, is totally different from the heart-shaped leaf of an eastern redbud. Note that leaves can be described by observing their base, their margin, their veins, and their tip or apex. Each aspect has a name and is used as part of the identification process.

Leaf Structure

Water drop on leaf
MirageC / Getty Images

A leaf can either be simple (no extra leaflets) or compound (three or more leaflets). This leaf structure is always a help with tree identification because of each tree species' leaf structure.

On a simple leaf, the leaf blade is singly attached to a twig or twig stem. On a compound leaf, all leaflets are attached to a single leaf stem or rachis.

Compound leaves can be confusing because of the many variations of leaf structure. The major differences are palmate leaves, leaflets or lobes that grow from a leaf stem in the manner of a hand. Pinnate leaves grow leaflets on opposite sides of a ​leaf stem.

There are also leaves that have double-compound or twice-compound leaflets.

Flower, Cone, and Fruit

Forest and Fruit Trees and Plants, Victorian Botanical Illustration
Forest and Fruit Trees and Plants, Victorian Botanical Illustration. bauhaus1000 / Getty Images

Besides its branches, roots, and leaves, a mature tree also grows another important structure—the flower (or cone, in the case of evergreens). Flowers are the reproductive structures from which seeds are produced.

Seed pods, cones, flowers, and fruit are major markers that help in keying out and identifying specific species of tree. Not as dependable as a leaf, a fruit or seed pod might only be found at certain times of the year. Leaves generally hang around either on the tree or on the ground beneath the tree.

Reproductive structures are great sources for tree identification. The acorn of an oak tree, for example, is a seed—but completely different from a maple's samara.

Twig

Twigs and Sticks
ivanastar / Getty Images

Believe it or not, twigs can be used to identify a tree as well. This is a good thing because they are about all that remains of most trees during the dormant months of winter. Twigs and buds are generally not used to ID a tree during late spring through early summer.

Twigs have structures called buds, leaf scars, and bundle scars that vary from species to species. Thorns and spines can occur on twigs and are unique to certain trees. The twig pith sometimes has unique "chambers" and/or a specific shape. Other twig structures used in tree identification include stipule scars, bud scale, and fruit scars, spur shoots, and lenticels. Twigs are a great marker if you know what to look for.

Bark

Detail of tree trunk with background forest
James O'Neil / Getty Images

The bark is a tree's natural armor and protection from external threats. Bark also has several physical functions; one is ridding the tree of wastes by absorbing and locking them into its dead cells and resins. The bark's phloem transports large quantities of nutrients throughout the tree.

Xylem carries water and minerals from the roots to the leaves. Phloem carries manufactured food (sugars) from the leaves to the roots. The cambium (a watery layer only a few cells thick) is the generative layer, giving rise to both xylem and phloem.

Bark textures are relatively uniform by tree species and make a great visual marker for broad tree identification. Textures are divided into at least 18 types, from smooth (beech) to spiny (locust). For this reason, only the broadest classifications can be determined using bark alone. You can very readily distinguish between an oak and a pine by looking at the bark. The hard part is separating the various oak or pine species without looking at additional tree features.

Tree Shape or Silhouette

Landscape with the silhouette of an alone solitary tree in a great plain, one night with crepuscular light to the late afternoon. Bocairent, Valencian Community, Spain.
Jose A. Bernat Bacete / Getty Images

Though not technically a part of a tree, the tree shape is still a distinguishing feature and another way to help in its identification. Naturalist Roger Tory Peterson says that unlike the precise silhouette of birds, a tree is not so consistent in form or shape: "The beginner, learning his trees, yearns for a book that will give him shapes and field marks by which he can make snap identification. But it isn't that easy...within limits, one can with practice, recognize by shape and manner of growth quite a few trees."

A yellow poplar will always look like a yellow poplar in a very general sense. However, a young tree may look entirely different from the parent tree. A forest-grown tree may grow tall and slender while his field-grown cousin develops a maximum crown in the open sun.

The most common tree shapes include broadly conical, broadly columnar, narrowly conical, narrowly columnar, and broadly spreading. Even with these shapes, though, you will obviously need more information to identify certain trees by species.