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How to Identify Trees by their Leaves

Tree Leaf Identification

Most of us can appreciate trees for their aesthetic appeal, the many uses of wood, their fruits and their overall environmental value.  True appreciation of trees however comes with more intimate knowledge, starting with identification by leaf, bark or other features, preferably instantly, like we can recognize the make of a car from a cursory glance.

There is good reason to recognize a Poison Ivy!

The size, shape, colors and density of a tree are of course all important, but to know what we are looking at, one trick lies in identifying trees and plants by their leaves.

The clues to Identifying Trees by their Leaves

Trees can be identified by the nature of  their leaves. The leaves show morphological characteristics.  Here are some features to note for tree identification by leaf:

  • Are they broad or needle-shaped?
  • How are the leaves arranged on the stem?
  • Their edges tell a story
  • So do their sizes and leaf tips
Leaf Type.
The first character is whether leaves are present on the plant or not, and then whether leaves split into broad categories of leaf types.

Leaves may be present as needles, or scales, or leaves may not be produced at all. Leaves may also produce a normal blade, or may be very large, as in palm fronds and bananas.

The stalk, or petiole, that connects the leaf blade to the stem may provide useful characters. It may be shortened or very long, round or flat, or even with a wing on each side. Small leafy scales, stipules, may be present or absent at the base of the petiole, or may have a special appearance.

Chart Extracts

Glands or spines may be present on the petiole, or at the base. 

In palms, with very distinct leaves, there are basically four types of fronds.

 

Leaf Position.

Tree Leaf Position Identification

Tree Leaf Positioins

Leaves develop at shoot tips in bananas, palms and dracaenas. However, in the bulk of plants they are displayed in different patterns along the lengths of branches. In this key, there are basically three different positions used: opposite, alternate and whorled.

The leaves of ash trees, maple, and dogwood are on the opposite sides

Needle shaped leaves are mostly found in evergreen trees like the conifer family that includes pine, fir, cypruss and spruce trees.

Describing Leaves.

Leaves can be distinguished by their size and the length of the petiole.  The shapes and details of the leaf blades are also very useful characters.

Recognizing the differences in Tree Leaf Edges for Identification

Tree Leaf Edges

The edges of the leaves provide a variety of characters easy to distinguish.

The differences among leaf shapes may be difficult to distinguish, but we use just a few categories here that should be easy to use for these trees.


Identification of Tree Leaf Shapes

Different Shapes

Features at the tips of the leaf blade also vary and are consistent for tree species.

The base of the leaf blade may also be useful.
  
Compound versus simple leaves. The leaf is a fundamental unit of tree growth, along with branches, roots, flowers and fruits.

Plants, by their very nature, respond dramatically to the physical stresses of  their environments, in stark contrast to the lack of plasticity in animals. However, in this very open ended pattern of development, leaves are highly determined in their growth. They may vary some in their size, thickness and degrees of lobing, particularly in response to shading.  The leaf characters described above are highly reliable in identifying trees.

This article was extracted from  Wayside Trees of Tropical Florida , a guide to the native and exotic trees and palms of Miami and tropical south Florida David Lee and Stacy West, Tellus Books Mebane, NC.

Follow the link above for a comprehensive Key for identifying trees by leaf, bark and other features.

he Marjorie Stoneman Douglas Nature Center in Crandon Park on Key Biscayne is also an excellent place for learning about trees, particularly those that are adapted to live on coastlines. This Center has many educational activities and can be accessed at: http://www.biscaynenaturecenter.org

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