Hiking is one of the best ways to relax and reconnect with nature. Going outdoors has been found to help manage everything from diabetes to heart disease to depression. Doctors in Scotland are literally Prescribing Nature to Their Patients. One of the best ways to enhance your experience in nature is to be able to understand natures signs or identify things around you. One of my favorite ways to elevate my hiking experience is by identifying trees.
Tree identification is fun and easy once you know some basic principles. There are some great field guide books to assist you when you are “stumped”. You will quickly be astounding your friends and family when you say “Hey look at that mighty Sycamore” or “Shag Bark Hickory is my favorite tree" while on the trail.
My two favorite field guides are Peterson’s Field Guide to Eastern Trees and The Sibley Guide to Trees. They both have their strengths and weaknesses. Peterson’s Field Guide to Eastern Trees guide is best to identify an unknown tree via a dichotomous key. The Sibley Guide to Trees strength lies in its detailed illustration of every species’ leaves, seeds, twigs, buds and bark.
What is a Tree?
What is a Tree? This seems like a no brainer, right? However, it is important to distinguish between a tree and a large bush. A tree is a perennial plant with a single woody stem at least a few inches thick at about four feet above the ground, branching into a well-formed crown of foliage, and reaching a height of 12-20 feet (Sibley). Sure, there are saplings (i.e. baby trees) that are smaller than this, but when young, they may not display the distinguishing characteristics described in field guides.
Now that we know we have a tree, the next step in identifying its species is to categorize its morphology or physical characteristics. Understanding these categories is essential to quickly identifying known trees. Being able to distinguish these field markers will aid you when using your field guide's dichotomous key to discover a species unknown to you.
Softwood or Hardwood?
The first categorization is to figure out if the tree is a softwood or hardwood. Many people think this is synonymous with “evergreen” and “deciduous”, respectively. This is a misnomer. There are trees with needles that are deciduous like the bald cypress and trees with leaves that are evergreen such as the holly. To properly classify softwood and hardwood it is as simple as asking “Does this tree have needlelike or scalelike leaves OR does it have broad leaves?” Softwood trees have needlelike or scalelike leaves and are considered gymnosperms meaning “naked seed”. A pinecone is an example of a naked seed. Hardwoods are the broad leaf trees and are angiosperms which means “fleshy seeds”, think apples.
Arrangement: Opposite or Alternate or Whorl?
The next level of categorization is the leaf and twig arrangement. There are three ways the leaves and twigs are typically arranged: opposite, alternate or whorl. Opposite arrangement means the leaves and twigs oppose each other. It is a good idea to look at the whole tree because there can be some variation. However, once you find one leaf or twig that is opposite, chances are good the tree has an opposite arrangement. If you found an opposite arrangement (in the northeast), you can be assured that you have a tree of the maple, ash or dogwood family. Remember the acronym “MAD”.
In an alternate arrangement, the leaf does not have another leaf opposing it. The leaves and twig alternate from side to side. Again, it is a good idea to look at multiple leaves and twigs on the tree to eliminate error due variation.
Whorled arrangement is not common, but it can be found in some Northeastern species. The whorled arrangement has more than two leaves or twigs around the circumference of the same location on a branch.
Composition: Simple or Compound
A simple leaf is undivided whereas a compound leaf is divided into several leaflets. To figure out if you have a simple or compound leaf, the trick is to locate the lateral bud. Each leaf, no matter its composition, will have a bud at its base on the twig. Leaflets do not have buds at their base. If you see a bud, and there is a single leaf, the composition is simple. If you found a bud, and the leaf stem (petiole) has multiple leaflets, then you are looking at a compound leaf. Compound leaves are more complex and can be in different arrangements such as palmately (hand-shaped) or pinnately (feather-shaped) compound.
Evergreen or Deciduous?
It is fairly easy to determine if a tree is evergreen or deciduous (i.e. lose their leaves in Fall and grow new ones in Spring). The key is to look at this years growth and go up the twig. For deciduous trees, you will see evidence of past year’s growth. You will see “scars” on the twig from past years leaf growth. For an evergreen, you will see this years growth along with years past along the twig. In general, trees with needles are evergreen and trees with broad leaves are deciduous. But be careful, there are exceptions. Holly, as mentioned earlier, has broad leaves, but is considered evergreen. In contrast, the bald cypress has needles, but is a deciduous conifer tree.
The leaf shape will help you continue down the path of identifying a species of tree. Common shapes include ovate (egg shaped), lanceolate (long and narrow), deltoid (triangular), obicular (round) and cordate (heart shaped). There is also the palm-shaped maple leaf and the lobed oak leaf, two of our most recognizable leaf shapes. The leaf edge is also an important characteristic. Leaf edges or margin can be smooth, sharp or serrated like a steak knife. Some toothed leaves, for example, have clearly defined serrations, while others have much finer serrations resembling a fringe or hair.
Using the characteristics above, you can use the dichotomous key of a field guide to narrow down the species of tree in question. Using a dichotomous key is simple if you can clearly identify the field markers. It is important to understand the “lingo”.
A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish. Keys consist of a series of choices that lead the user to the correct name of a given item. "Dichotomous" means "divided into two parts”.
My favorite field guide, Peterson’s Field Guide to Eastern Trees, has a straight forward approach to tree species identification. Peterson’s Field Guide to Eastern Trees is broken up into 6 sections based on the leaf type (needlelike or scalelike, palms, or board leaves), arrangement (opposite or alternating) and composition (simple or compound). I like to use the illustrations of the 6 sections as my starting point, but there is also a dichotomous key (page 11 in my edition) For example, you may have a tree with alternate simple leaves or section V. This will direct you to page 255, Plates 23-46 in my edition.
You will then be presented with another dichotomous key. We begin to drill down on other characteristics. If you are unsure what each means, the Peterson’s Field Guide to Eastern Trees has explanations of each key feature in the front of the guide.
The final step is to thumb through the plates directed by the last dichotomous key. Peterson’s Field Guide to Eastern Trees gives an explanation of the species, the distribution of the tree, a picture of the tree and/or bark as well as illustrations of the leaves and seeds. The field guide may also give another chart with further characteristics with pluses (+) or minuses (-) if a given species displays those features.
Tree identification is fun and easy. With a little practice and patience, you will be wowing your fellow hikers in no time. I have included a few great reference videos below. I highly suggest Peter Collin’s videos. He is local to Western NY and his videos are set in Letchworth State Park.
- Tree Identification Northeastern Softwoods
- Tree Identification Northeaster Hardwoods
- Tree Identification Understory Species
- Mop-up Part 2
Another great resources is ForestConnect, an educational program of the forestry extension and applied research group at Cornell University and through Cornell Cooperative Extension. ForestConnect's intent is to connect people to the forest, with special attention to the 650,000 woodland owners in New York. ForestConnect’s has a great YouTube channel with many educational webinars on trees.
It's more fun to figure it out yourself.
And if the field guides fail you while on your hike, grab a leaf sample from your unknown tree, place it on a white sheet of paper and use the app LeafSnap to assist you with identification. However, it's more fun to figure it out yourself.