THE TREE DOCTOR (aka The Plant Doctor)

Ash Tree Identification Guide

Ash Identification Guide


Ash trees (Fraxinus species) are easily identified if several simple factors are understood. Ash is unique from other trees because of the following distinctive characteristics: opposite branching and compound leaf according to the following descriptions of pictures. Remember, mountain ash (Sorbus) is not a true ash (Fraxinus), and is not affected by the Emerald Ash Borer.

Opposite Branching - MAD Horse


Very few trees in our landscapes and forests have opposite branching. The predominant types are Maple, Ash, Dogwood and Horsechestnut. A simple phrase to remember when identifying trees with opposite branching is to use the acronym *MAD Horse* representing  Maple,  Ash,  Dogwood &  Horsechestnut.  When looking for opposite branching in trees, please consider that buds or limbs may die; hence not every single branch will have an opposite mate.

 
A branch with smaller branches growing out, opposite each otherRed dots mark opposing branches
The underneath side of a branch with smaller branches growing opposite of each other

Underneath side of another branch

 
 
Opposing branches with red dots showing where they mirror each other

Another example of opposing branches

A bare ash branch in the fall

A fall skeleton of an ash branch

 

Compound Leaf


A simple leaf is a single leaf defined by having a bud at the base of the leaf stem (also known as a petiole).
A compound leaf is one that has more than one leaflet while the entire leaf, as defined, has a bud at its stem base (petiole). Ash typically have approximately 5-9 leaflets per leaf.

 

Adult Emerald Ash Borers on a young ash leaf

Very young ash leaf with adult EAB

An ash leaf with 9 leaflets growing out of it

Ash One leaf, 9 leaflets

A green ash leaf with 7 leaflets growing off of it

Green Ash One leaf, 7 leaflets

An ash leaf with 9 leaflets

Ash One leaf, 9 leaflets

A black ash leaf with 7 leaflets

Black Ash One leaf, 7 leaflets

A white ash leaf with 7 leaflets

White Ash top/bottom One leaf, 7 leaflets

A box elder branch with 3 leaves, each having 3 leaflets

Box Elder - Branches with 3 leaves shown; each having 3 leaflets. Same as Maple leaves.

 
 

 

Following are leaves of Maple, Ash, and Dogwood, which have opposite branching (MAD Horse):

A maple leaf

Maple - one leaf

An ash leaf

Ash - one leaf with 9 leaflets

A dogwood branch with 6 leaves

Dogwood - 6 leaves on branch

Bark Patterns


Seeds and bark of ash are also unique. Some older ash trees have a characteristic diamond pattern to their bark.

 
A healthy ash branch

A close-up of a healthy ash branch with seeds!

A detailed ash trunk

Nice details on this mature ash trunk and branches

 
 
 
 
 
Smooth bark on a young ash tree

The bark on a younger ash tree is relatively smooth.

A trunk with a diamond pattern

Green ash - As the tree ages the bark thickens and a diamond-like pattern in the raised bark is noticeable.

 
 
A very thick, ridged ash trunk

This ridged trunk section is from a very mature ash tree.

 
 

Alternate Branching


Following are leaves from trees that may look like ash but have alternate branching:

A hickory leaf

Hickory - One leaf with 5 leaflets

A hophornbeam branch

Hophornbeam - Many leaves on branch

A walnut leaf

Walnut - One leaf with many leaflets

 

Other Web Resources


Alternatives Selections for Problems in Tree Species (PDF)