Tree of the Week: An (almost) evergreen ash from the olive family? It’s a shamel

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Shamel ash – Fraxinus uhdei

Dozens of different species of ash trees grow around the world, all part of the olive family. Fairly fast growing, they are used for street, shade and lawn trees; their hard, high-strength wood provides tool handles, baseball bats, veneer, bodies for musical instruments and firewood. Some species exude a sugary substance, which the ancient Greeks called meli (honey) and harvested commercially.

Ash trees became newsworthy when the emerald ash borer, a wood-boring beetle accidentally introduced in this country from east Asia around 1998, started threatening billions of ash trees nationwide.

The shamel or tropical ash is one of the few (semi)evergreen ashes; this Mexican native is a favorite in Southern California. The tree was also introduced in Hawaii but started escaping in the wild. Here in our drier climate it is better behaved.

The shamel ash grows fast to eventually reach 70 or 80 feet. Initially upright and narrow, in later age it may widen to 60 feet. A slower growing variety is available. (As always, these measurements assume that tree trimmers don’t impose their own will on the shape of the tree).

The upright trunk is covered in gray bark, split in small parallel pieces. The tree is notorious for developing V-shaped crotches. These narrow angles of attachment are found on main upright branches that often compete with the main trunk in size. They are weakly attached to the trunk, prone to break off and very difficult to prune. It is much easier to get rid of them when they are little. Lateral branches are opposite, a family trait.

Foliage is luxuriant green, and like most ashes, opposite and pinnately (bird feather-like) compound. The five to nine glossy leaflets, finely toothed at the edge, are about 4 inches long.

Some people are allergic to the flowers. Female trees carry barely noticeable clusters of small green flowers, which in summer develop into samaras, dry fruits with brown papery wings on one or both sides, which spiral down as they fall upon ripening. The accompanying picture shows the load of samaras one tree can carry. The tree is drought-resistant but does much better with regular water; it loves a lawn location but eventually the shallow roots may start lifting nearby pavement. The tree is not particular as to soil but wants full sun. The shamel ash is a reliable tree as long as it receives structural pruning when young it and it gets room to spread out when old.

The name ash is used to designate species of the genus Fraxinus, but also those of Sorbus (mountain ash), while in Australia some Eucalyptus are also called ash.

-- Pieter Severynen

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