Ash trees, belonging to the genus Fraxinus, do not produce nuts. These common deciduous trees, which are part of the Oleaceae family, instead produce a specialized winged fruit called a samara. Ash trees are widespread across North America, Europe, and Asia, and their reproductive strategy is distinct from that of nut-bearing trees.
The Reproductive Structure of Ash Trees
The reproductive structure of the ash tree is a dry, flattened fruit known as a samara, which is commonly referred to as a “key”. This fruit consists of a single seed encased in a thin, papery wing that extends from one side. The wing’s design is specifically adapted for wind dispersal, a process known as anemochory.
As the samara falls from the tree, the wing causes it to autorotate, or spin, which slows its descent and allows the wind to carry the seed a greater distance. The samaras typically mature and are dispersed in the fall, often hanging in dense clusters on the branches of female trees.
Samaras Versus True Botanical Nuts
Botanically, a true nut is defined as a dry, indehiscent fruit that contains a single seed and develops a very hard, woody outer shell, or pericarp. Indehiscent means the fruit does not split open at maturity. Examples of true botanical nuts include acorns from oak trees and hazelnuts.
The ash tree’s samara contrasts sharply with this definition. While both samaras and true nuts are indehiscent dry fruits, the samara lacks the thick, hard, protective shell that characterizes a nut. Instead, the ash samara has a slender, thin seed cavity covered by a fibrous, papery wing, enabling its lightweight, spinning flight.
Identifying Features of Ash Trees
Beyond their unique samaras, ash trees possess several other identifying physical characteristics. The most reliable feature for identifying a tree in the Fraxinus genus is its opposite branching pattern. This means that branches, buds, and leaves grow directly across from each other on the stem, rather than alternating along the twig.
The leaves themselves are pinnately compound, appearing feather-like, with multiple leaflets—typically five to nine—arranged in pairs along a central stalk. Mature ash trees, such as the White Ash, often develop a distinctive bark texture featuring deep furrows and crisscrossing ridges that form a diamond-shaped pattern. In winter, the European ash is easily recognized by its distinctive black, velvety terminal buds, which are also arranged oppositely on the twigs.