Tree Identification - Donna Rogler

Director of Education, Catskill Forest Association, PO Box 336, Arkville, NY 12406.    (914) 586 - 3054


Introduction

The best place to study trees is in the woods. However, at this workshop, we will bring the trees (or parts of them) to you to get you started with the basics of tree identification. This workshop will familiarize you with identifying characteristics and show you how to use a dichotomous key.

When studying trees, try to use more than just your eyes ˆ smell, touch and/or taste can sometimes help distinguish between two very similar species. Trees vary in almost every way possible ˆ size, shape, color, form, structure, life requirements, resistance to disease ˆ yet some are so similar it takes a trained eye to find the smallest identity clues. Each kind of tree has dependable ways by which it can be recognized. Keep in mind not to concentrate on just one feature of a tree. Learn other characteristics of the tree at the same time. While it may seem impossible at first, with practice, you will begin to see the differences, even from a distance.

Tree Characteristics

For the beginner, the easiest place to start identifying trees is looking at the leaves. They are the features that catch the eye. Shape, color, texture and arrangement are important. Leaves can be simple or compound (many leaflets attached to a leaf stem=one leaf). Also notice the shape of the leaf, is the margin entire, toothed, or lobed? For example, red oak has simple leaves that are lobed, while white ash has compound leaves with leaflets that are entire. Colors do vary. Although green is green, the differences are subtle, but nonetheless, can be an important characteristic. Touch the leaf on the top and bottom surfaces to determine if it is smooth or fuzzy. Are the leaf stems opposite or alternate as they grow from a twig? Remember that in most species, leaves are present for only a few short months and cannot be relied upon in the winter. Other characteristics are present year-round and should be learned at the same time as the leaves. Bark is a feature that is present throughout the year. The important characteristics are color, thickness, texture, and pattern. Color varies greatly. Look at a few trees around your yard and you will probably find bark in different colors of brown, tan, and gray. Use your fingers to feel the bark ˆ is it smooth or rough? You can use a pocket knife to scrape the bark to determine its thickness. Also notice if the inner bark is the same, or a different color than the outer bark. Finally, look at the pattern the bark makes ˆ are there ridges and furrows or scales and what pattern do they make? A good example is white ash bark which forms an interlacing diamond pattern. Notice if other features are present, particularly lenticils (small horizontal lines on the bark) or resin blisters.

Buds and twigs are other features to help with winter identification. Buds contain the next year‚s growth of flowers, leaves, and twigs and are unique to each species of tree. The size, number, scales, color, and arrangement are important in identification. They may appear singly or in clusters. Look to see if buds are rounded or sharp. Along with buds, pay attention to the twigs, which are only the end portion of a branch that constitutes the newest growth. Twigs also vary from tree to tree, but can be very helpful in identification. Notice the color, the thickness, the arrangement (alternate or opposite, like the leaves), and the smell. For example, black birch has a distinct wintergreen smell when the twig is broken. Is the twig smooth or hairy? Cut the twig with a knife and look at the pith (the center of the twig).

Putting it All Together

A dichotomous key is a useful tool in tree identification. Derived from two Greek words that, together mean „to divide into two parts,‰ a dichotomous key is based on the idea of making a choice between two alternatives. It is a scheme for identifying any unknown object under observation. Based on striking similarities and differences, the learner is presented with a pair of descriptions about a particular feature ˆ only one of which describes the feature being keyed out. The correct selection will guide you to the next pair of descriptions or to the name of the object being identified. For trees, summer and winter keys are available. Summer keys are based on leaves and winter keys, buds and twigs.

Think of tree identification as learning a new language ˆ you have to practice, practice, practice. Soon your mind will make the right connections with the identifying features of a particular tree and soon, when you see a distinctive bark pattern or a certain bud, you will automatically know what kind of tree it is.

 References

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