[10] Species are arranged into sections supported by phylogenetic analysis:[11][12] North American native ash tree species are a critical food source for North American frogs, as their fallen leaves are particularly suitable for tadpoles to feed upon in ponds (both temporary and permanent), large puddles, and other water bodies.

They produce much less suitable food for the tadpoles, resulting in poor survival rates and small frog sizes.

The emerald ash borer (Agrilus planipennis), also called EAB, is a wood-boring beetle accidentally introduced to North America from eastern Asia via solid wood packing material in the late 1980s to early 1990s.

The public is being cautioned to avoid transporting unfinished wood products, such as firewood, to slow the spread of this insect pest.

[21] Damage occurs when emerald ash borer larvae feed on the inner bark, phloem, inside branches and tree trunks.

[27] At the end of October 2012 in the UK, the Department for Environment, Food and Rural Affairs (Defra) reported that ash dieback had been discovered in mature woodland in Suffolk; previous occurrences had been on young trees imported from Europe.

Woodworkers generally consider ash a "poor cousin" to the other major open pore wood, oak, but it is useful in any furniture application.

Ash is not used much outdoors due to the heartwood having a low durability to ground contact, meaning it will typically perish within five years.

Due to its elasticity, ash can also be steamed and bent to produce curved stair parts such as volutes (curled sections of handrail) and intricately shaped balusters.

The Morgan Motor Company of Great Britain still manufactures sports cars with frames made from ash.

In Sicily, Italy, sugars are obtained by evaporating the sap of the manna ash, extracted by making small cuts in the bark.

The manna ash, native to southern Europe and southwest Asia, produces a blue-green sap, which has medicinal value as a mild laxative, demulcent, and weak expectorant.

In Norse mythology, a vast, evergreen ash tree Yggdrasil ("the steed (gallows) of Odin"), watered by three magical springs, serves as axis mundi, sustaining the nine worlds of the cosmos in its roots and branches.