There are a variety of characteristics that you can count on as useful tree identification aids. Some characteristics are common among all members of a genus, while some are specific to a particular species. For instance, all oaks have simple, alternate leaves. However, in Missouri only shingle oak has banana-shaped leaves. Both the similarities and the differences are useful identification tools.
Listed below are genuses or species that display characteristics useful for identification. They are trees, including a few ornamentals and shrubs, are commonly found in Missouri forests.
Trees with this characteristic bear their leaves and twigs in opposite positions on the stem. This trait can be very obvious on younger stems, but look closely on older stems, which can be affected by harsh weather and environmental conditions.
Trees with this characteristic bear multiple leaflets in a variety of patterns and numbers according to species. All true leaves have a bud at the base of the leaf stem; leaflets don't have buds at their bases. Although compound leaves are not present in winter, large leaf scars generally indicate a compound leaf. Usually you can find the rachises (the rachis is the stem-like formation that holds the leaflets of a compound leaf) on the ground below the tree with minute leaflet scars on them. With these, you can determine numbers of leaflets and patterns.
Trees with this characteristic do not have a bud at the end of the stem. Therefore, they display a zigzag pattern as the twig grows. This is more obvious on some species than others, but it is always a useful identification aid. This can be especially helpful in winter.
Trees with prickly appendages on their stems are easy to identify. Trees with modified branches, such as honey locust; prickly stipules, such as black locust; and thorns, such as hawthorn, fit in this group. As trees age, thorns may be lost or altered, but when they are present they are helpful.
Many trees and shrubs are fragrant, or their twigs have a distinct flavor.
Many trees have rough, knobby appendages on their bark. They may vary from few to many, short to tall, common to intermittent, etc. Though they may not be always present, they are useful when identifying trees.
These characteristics are very helpful if you carry a pocketknife. The pith is the soft, sponge-like material at the center of a stem or branch. Though typically white and round, color and shape may vary.
Buds without cover scales are referred to as naked. Some buds will have one scale completely covering the bud; some will have two. Others may have many multiples of scales.
On some branches, the buds are barely visible or are entirely surrounded by the twig.
Some buds are sharp and hard to the touch. Occasionally they are elongated, but they still have a sharp point.