Activity 5: Identifying Trees

A magnifying glass for examining a Sugar Maple Leaf.

MD DNR: Madeline Koenig & Kerry Wixted Photo / Kelly Savannah

In the world, there are over 60,000 different species of trees and trying to identify them can be very intimidating. However, having a good understanding of the different key characteristics of tree leaves can help when identifying distinct tree species. Using Tree ID Guides or App's can also help narrow the search. Let’s examine some 'Key Characteristics' of tree leaves!

 

Definitions:

Simple: 1 leaf (blade) attached to a stem known as a petiole. Where the stem meets the twig is a lateral bud.

Compound: Many leaflets (Multiple blades). Leaflets do not have lateral buds.

Opposite: This is the arrangement of how the leaf sits on the twig (small branch). In this case the leaf is directly across from another leaf.

Alternate: The leaves zig-zag along the twig (small branch).

Leaf Margin: Is the edge of a leaf. Some leaves will have smooth (entire) margins and others with have zig-zagged (toothed) margins.

Shape: The shape of a leaf is either lobed or not lobed. Therefore, if the leaf is lobed there are sections that are cut out whereas, if it is not lobed then the shape has a continuous leaf edge.

Base Shape: Refers to the shape of the base of a leaf. Some leaf bases are even, and some are uneven.

 

Identifying Physical Characteristics:

 

1. Determine the leaf type:

 

This image is of 3 different types of leaves: (1) Broad Leaf (image of a American Sycamore), (2) Needle Leaves (Image of a White Pine) and  (3) Scale Leaves (Image of Red Cedar Leaves).

Images 1 & 3 Credit: MD DNR: Madeline Koenig & Kerry Wixted and  Image 2 Credit: Wikimedia Commons.

 

2. Is the leaf simple or compound?

 

Comparing Simple leaves to Compound Leaves: (1) Simple Leaf (Image of a Mtn. Laurel leaf), (2) Lateral bud (Image of a Northern Red Oak) and (3) Compound Leaves (Image of a Black Walnut Leaf).

Images courtesy of MD DNR: Madeline Koenig & Kerry Wixted.

 

3. Are the leaves Alternate or Opposite?

 

Comparing Alternate to Opposite Leaves: (1) Alternate Leaf (Image of a American Beech leaf) and (2) Opposite (Image of Sugar Maple leaves).

Images courtesy of MD DNR: Madeline Koenig & Kerry Wixted.

 

4. What do the leaf margins look like?

 

Comparing Entire Leaves to Toothed Leaves: (1) Entire (Image of a Paw Paw leaf) and (2) Toothed (Image of a River Birch Leaf ).

Images courtesy of MD DNR: Madeline Koenig & Kerry Wixted.

 

5. Are the leaves lobed or unlobed?

 

Comparing the shape of the leaves: (1) Lobed (Image of a White Oak leaf) and (2) Unlobed (Image of a Persimmon [Fruit Tree] Leaf ).

Images courtesy of MD DNR: Madeline Koenig & Kerry Wixted.

 

6. Are the leaves even or uneven?

 

Comparing Leaf Bases: (1) Even Leaf Base (Image of a Redbud leaf) and (2) Uneven Leaf Base (Image of a  American Elm Leaf ).

Images courtesy of MD DNR: Madeline Koenig & Kerry Wixted.