Fraxinus (), commonly called ash, is a genus of plants in the olive and lilac family, Oleaceae, and comprises 45–65 species of usually medium-to-large trees, most of which are deciduous (dropping their leaves in autumn), although some subtropical species are evergreen. The genus is widespread throughout much of Europe, Asia, and North America.
The leaves are usually opposite, and mostly pinnately compound (divided into leaflets in a feather-like arrangement). The seeds, known as "keys", are botanically fruits of the type called samara. Some species are dioecious, having male and female flowers on separate plants.
Ash wood is strong and elastic, and used for the handles of tools. Musical instrument makers use it for electric guitars and for drum shells. The Morgan Motor Company makes the frames of sports cars from ash wood. In Greek mythology, the Meliae were the nymphs of ash trees.
Etymology
The tree's common English name, "ash", derives from the Old English æsc, from the Proto-Indo-European name for the tree, while the name of the genus originated in Latin frāxinus, from a Proto-Indo-European word for birch. Both words also meant "spear", as ash wood was used for shafts.
Description
The leaves of ash trees are usually opposite (rarely in whorls), and mostly pinnate. The seeds, known as "keys", are botanically single-winged fruits of the type called samara. Most Fraxinus species are dioecious, having male and female flowers on separate plants. The male flowers have two stamens. If a calyx is present, it has four lobes; if there is a corolla, it has four lobes or four petals, which are white or pale yellow.
Leafy shoot of F. angustifolia
Flowers of F. excelsior
Winged fruits (samaras) of F. excelsior
Evolution
The oldest fossils that are clearly Fraxinus are from the Middle Eocene (49–39 million years ago) of southeast North America, including the extinct species F. wilcoxiana. Fossil pollen of F. angustifolia is known from the Upper...
