Deciduous ash trees (Fraxinus) stand out from other trees with their compound leaves and opposite branching branches. Only a few other trees have such a unique characteristic. The compound leaf structure appears as a large single leaf with branching leaflets. Ash tree varieties sport 5 to 9 leaflets per leaf, according to Michigan State University. Native to Europe, Asia and North American, there are 65 ash species and many cultivars.
The ash tree grows as a medium or large shade tree, depending on the variety. Their average height ranges from 80 to 90 feet. The two largest varieties of ash are the green ash and the white ash tree. The green ash normally stands slightly smaller than the white ash.
All ash trees are highly adaptable to their planting location. They tolerate a wide range of soils with ease, but heavy soil will slow their growth rate. The trees do require moist soil to thrive. Once established the trees can survive seasons of drought but their growth will be reduced during such dry spells.
North American Varieties
The white ash is a highly valuable timber tree due to its elastic toughness. It is used widely in furniture manufacturing. The European ash tree is rarely seen in the United States. The Biltmore ash holds value as a timber tree in North America. Black ash tree wood has been widely used throughout history by Native Americans. Today, the wood of the black ash is widely used in furniture production. The green ash is used in home landscapes and covers a vast majority of the United States naturally. The blue ash is rarely sold as a landscape specimen.
As ash trees age, most produce bark in a unique diamond pattern that stands out from other trees. When young the trees have smooth bark. but with age it becomes more ridged and thicker.
Dioecious ash trees are either male or female. Pollination is predominately wind driven. The female tree is often least desired in the home landscape due to the messy seed production. Various cultivars have been released with reduced seed production. Seed dispersal is achieved by the wind and animals. Ash tree seeds have been known to be wind driven 300 feet from the parent tree, according to the U.S. Forest Service. The seeds remain viable for 3 to 4 years. The seeds do require a period of cold stratification in order for germination to be achieved.