Helpful Tips for Tree Leaf Identification

Just like how knowing the names of neighbors makes you feel part of a community, tree leaf identification in your yard or on nature hikes can similarly make you feel more connected to your local landscapes. But how do you start identifying trees?

Botanists use everything from the branching patterns to the bark texture to figure out the species. However with plants everywhere leafing out for the summertime, using the tree leaves to identify species provides greater ease and accuracy.

These helpful tips for tree leaf identification are a sure way to start learning the names of trees.

Oaks are an example of simple, lobed leaves. Image from Analogicus on Pixabay.

What Is a Tree?

The first step to tree leaf identification is finding a tree! While plants can often be delineated into different families (e.g. the rose family, the nightshade family, the pine family), ‘tree’ isn’t one of these classifications. In fact, most plant families include both herbaceous plants and trees. So what is a tree? 

With some variation on specific heights and diameters, most sources can agree on a few general characteristics that set trees apart from other plants:

• Trees are perennial. Many trees have long life spans, lasting hundreds of years. 

Fun Fact: The oldest living tree is a bristlecone pine (Pinus longaeva) that is over 4,700 years old. 

• Trees are woody. Trees have a woody stem or trunk, and most trees have thick bark that adds to their protection.

Fun Fact: Giant sequoias (Sequoiadendron giganteum) have the thickest bark, sometimes measuring over two feet thick.

• Trees are tall. Most trees grow to a considerable height, with different branching patterns.

Fun Fact: Coast redwoods (Sequoia sempervirens) reach the tallest heights, with a record of almost 400 feet.

Once you have a tree picked out, use the tips below to start narrowing down the species.

Where in the World? Get a Good Field Guide.

Because most tree species grow specific to a certain region, knowing what species grow in your region helps quickly narrow the options for tree leaf identification. The Rocky Mountains create a distinct change in climate and ecosystem in the center of North America.

Consequently tree species tend to differ east and west of this continental spine, and many field guides reflect this distinction by providing eastern and western versions.

Both the National Audubon Society Field Guide to North American Trees and the Peterson Field Guide Series have a guide for the region east of the Rockies and one that covers the land from the Rocky Mountains to the west coast.

For more localized guides, check out your state’s forest service website.

The Two Types of Tree Leaves

Identifying tree leaves starts with a simple first question: are they scaly and needle-like or are they broad and flat? All trees can initially be divided into the two main categories of gymnosperms and angiosperms depending on their type of leaf and mode of reproduction.

Gymnosperms

On the other hand, gymnosperms have scaly or needle-like leaves, and often do not shed them seasonally. Consequently, most are thought of as evergreen, with the exceptions of Ginkgo, Dawn redwood, and Bald cypress that all drop their leaves.

Gymnosperms produce cones or cone-like structures for reproduction and are generally wind-pollinated. For example, some common types of gymnosperms include:

• Pine
• Fir
• Spruce
• Juniper
• Cedar

Angiosperms

Often losing them in the winter, the leaves of angiosperms are usually broad and flat. Additionally, these trees can be identified by producing flowers and bearing fruit. Examples of angiosperms include:

• Oak
• Maple
• Alder
• Beech
• Aspen

Gymnosperm Tree Leaf ID Tips

To identify gymnosperms by the leaf, it’s all about the needle (or needles in many cases)! The number of needles in a group along with their length and shape all help guide identification.

Longleaf pines have needles that can grow up to 18 inches long. Image from Fullersa on Pixabay.

Tip 1: Needle Number

For some gymnosperms, the branches and twigs are lined with single needles while others have needles that are bundled into groups with papery sheaths called fascicles. If your evergreen tree’s needles are grouped, it’s a type of pine! For instance, the table below organizes some of North America’s most common pines by their needle number.

While there is one type of pine that only has one needle in each fascicle, the Single-leaf pinyon is the exception that proves the rule. Otherwise, trees with single needles fall into different categories such as spruces, firs, and hemlocks.

Tip 2: Length & Shape

Secondly, taking a closer look at the length and shape of the needles can really help you with tree identification. For instance, the needles of spruce, fir, and hemlock trees are all about one inch long – much shorter than their pine counterparts. That is to say, most pine needles are over two inches long, with the Longleaf pine growing needles up to 18 inches! 

A common confusion with tree leaf identification is differentiating between spruce and fir trees. Both kinds of needles are about the same size and to make things more confusing, they often grow in the same forests.

So how can you tell the needles apart? This is where the needle shape comes into play as the cross-sections of the needles are distinctly different. In short, spruce needles have a square cross-section compared to the flatness of a fir needle.

To test, try to roll a needle between two fingers. If it rolls easily, it’s a spruce. If it won’t budge, it’s probably a type of fir. Additionally, spruce needles are also sharply pointed where fir needles are soft. 

Tip 3: What if It’s scaly?

There are some trees in the gymnosperm group that don’t follow any of these needle guidelines because they don’t have needles.

Gymnosperms can also have scale-like leaves, but will often still produce true cones or modified cones instead of flowers for reproduction. For example junipers, cedars, and sequoias all have scale-like leaves. 

Angiosperm Tree Leaf ID Tips

Angiosperms present a whole new set of challenges for leaf identification. Because angiosperms are more widely spread and diverse, there is naturally a much greater variety in their leaves.

Chestnut trees have palmately compound leaves. Image from PublicDomainImages on Pixabay.

Tip 1: Simple or Compound

A great first step to identifying angiosperm tree leaves is to decide if it’s a simple or compound leaf. A simple leaf blade is undivided while a compound leaf is composed of several leaflets that are independently attached to the center vein.

A good way to observe the difference is to first identify where the leaf attaches to the branch, and then see if the leaf is single or made up of smaller leaflets. Common trees with simple leaves include maples, oaks, sycamore, and aspen that come in different shapes, expanded on below. On the other hand trees with compound leaves come in a few varieties including:

• Pinnate – leaflets are arranged on either side of the center vein like a feather (e.g. pecan, walnut, ash)

• Palmate – leaflets divide from a common point, like the fingers of a hand (e.g. chestnut and buckeye)

Tip 2: Opposite or Alternate

After deciding if the leaf is simple or compound, the next step is observing how the leaves grow in relation to one another. Botanists place leaves into two categories: opposite and alternate.

As you might imagine, opposite leaves grow directly across from one another on the same twig, while, on the other hand, alternate leaves display a staggered pattern on a twig.

Many more tree species have alternate leaves than opposite, so if your tree has opposite leaves, that narrows the selection down quite a bit!

Tip 3: Shapes & Edges

Finally, to get further clarity on the tree leaf ID, you can try identifying characteristics of its shape and edges. A great first question to ask regarding shape is if the leaf is lobed or not. Lobes are defined as partial divisions of a leaf.

To clarify, a lobed leaf differs from a compound leaf as the leaf does not separate fully into distinct leaflets. For example, tree species with lobed leaves include maples and oaks. 

In the same vein, taking a closer look at the leaf’s edges can help you ID the tree leaf. From undulating waves to intense serrations, leaf edges often differ dramatically between species.

To sum up, with these tree leaf identification tips, now you have the superpower to learn the names of trees in your neighborhoods and in your local forests. 

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