Trees come in various shapes and sizes but all have the same basic structure. They have a central column called the trunk. The bark-covered trunk supports a framework of branches and twigs called the crown. Branches in turn bear the leaves.
A 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. The growth of new tissue takes place by the division of specialized cells located at the tips of branches and roots and in a thin layer just inside the bark.
Trees have reproductive structures; either flowers or cones. Leaves, bark, twigs and fruit can make quick work of tree identification. Shape plays a key role in tree species characteristics.
Leaves are the food factories of the tree. Powered by sunlight, the green substance chlorophyll uses carbon dioxide and water to produce life-sustaining carbohydrates. The process is called photosynthesis. Leaves are also responsible for respiration and transpiration. A tree’s leaf is one major marker that helps in identifying any species of tree. Most trees can be identified by the leaf alone.
Leaves come in many shapes and sizes. The “star” shape of sweetgum is totally different from the heart-shaped leaf of an eastern redbud.
A mature tree grows another important structure – the flower (or cone, in the case of evergreens). These are the reproductive structures from which seeds are produced. These seed pods, cones, flowers and fruit are markers that help in identifying a specific species of tree.
Twigs can be used to identify a tree. Twigs have structures called buds, leaf scars and bundle scars that can be different on different species. Thorns and spines can occur on twigs and are unique to certain trees.
The bark rids the tree of wastes by absorbing and locking them into its dead cells and resins. Also, 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 is the generative layer, giving rise to both xylem and phloem. Bark textures are divided into at least 18 types, from smooth (beech) to spiny (locust).