July 15, 2020

The Power of the Singleleaf Ash

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What North American Ash has the power to thrive in high elevations, dry and rocky canyons and has simple, not compound, leaf? If you've been out exploring in the Utah wild you've seen these super Ash trees called the Singleleaf Ash! 

Singleleaf Ash is native to the southwestern United States, where it grows in a number of habitats. It is unusual in the genus in that some (though not all) specimens have simple leaves instead of the pinnate compound leaves more characteristic of the group. be sure to take a closer look. This may be an adaptation for survival in the hot, arid environments in which the single-leaf ash lives: unsplit leaves reduce the surface area through which water is lost by a process called transpiration. It is also sometime called a dwarf or shrub ash. The leaves are almost always whole, not split into divisions. Each set of arrows in the second photograph at left points to the rarely occurring tri-foliate leaves, i.e., each leaf is divided into three leaflets. 

It's name history is interesting too. Linnaeus named this genus in 1753: "Fraxinus" is the ancient Latin name given to Ash trees. Fraxinus anomala was collected by Newberry and Palmer independently in Utah in the late 1850s and was named by John Torrey in 1871.

If you are interested in planting this ash you can learn more online. Prune regularly to promote health, provide air circulation, maintain a desirable shape, and to remove dead or damaged branches. Pruning is best done in late-winter to early spring for most trees and late-spring for spring blooming trees. Choose species that are resistant to pest damage. Monitor the tree for pests, diseases or other ailments on a regular basis. Protect the trunk especially where maintenance activities, such as mowing, may cause damage. Newly planted trees in areas with high exposure should have the trunk protected during the winter. Although  Fraxinus anomala most often grows with a vertical posture, it is common to find it sprawling in an intricate shrub pattern. Fall colors are a bright golden yellow.