Common Name: Black Ash

General Information

Fraxinus nigra is a deciduous tree that can grow up to 25 metres tall.
The plant is harvested from the wild for local use as a medicine and source of materials. It is grown as an ornamental
Fraxinus nigra is suffering the devastating impact of a recently introduced invasive pest, the Emerald Ash Borer that has rapidly spread across much of its native range and shows no sign of stopping. A population decline of at least 80% over the next 100 years (and likely much faster than that) is assumed for this species. The plant is classified as 'Critically Endangered' in the IUCN Red List of Threatened Species(2017)[].

Known Hazards

None known

Botanical References

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Range

Eastern and central N. America - Manitoba to Newfoundland, south to Iowa, Illinois and Virginia

Habitat

Deep cold swamps, river banks and shores, tolerating some standing water; at elevations from sea level up to 900 metres[, , ].

Properties

Conservation Status	Critically Endangered
Medicinal Rating
Habit	Deciduous Tree
Height	25.00 m
Growth Rate	Slow
Pollinators	Wind
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Fraxinus nigra is a moderately cold-hardy plant, able to tolerate temperatures down to around -15°c when fully dormant.
Prefers a deep loamy soil, even if it is on the heavy side[, ]. Most members of this genus are gross feeders and require a rich soil[, ]. A plant of swamps in the wild, in Britain this species requires a moist to wet soil[]. It succeeds when growing in exposed positions[] and also in alkaline soils[]. Plants are tolerant of atmospheric pollution[].
A moderate to slow-growing tree in the wild[], it is not a great success in Britain, where it is often damaged by late frosts[].
A recently introduced invasive pest, the Emerald Ash Borer has rapidly spread across much of N. America and is devastating the genus Fraxinus. The borer infests and feeds on all the North American ash species it has so far encountered. The nature of the infestation (larval feeding in the phloem) effectively girdles trees as small as 25mm in diameter, which is many years before reproductive maturity, leading to death within five years of infestation. The borer therefore causes virtually 100% mortality of Ash populations. The Ash species are unable to persist for very long through vegetative reproduction, and seeds only remain viable in the soilfor at most 7 - 8 years, so regeneration after borer infestation is minimal or nonexistent. Furthermore, the borer persists in forests in low population densities after major ash population crashes, so the orphaned cohort of ash seedlings that remains is quickly infested as they reach a suitable size[].
This species is closely related to F. mandschurica[].
Trees can bear hermaphrodite flowers, separate male and female flowers, or flowers of one sex only[].

Edible Uses

None known

Medicinal

The leaves are diaphoretic, diuretic, laxative[]. They should be gathered in June, well dried and stored in airtight containers[].
The inner bark has been used as a tonic for the liver and stomach, to check vaginal discharge and to treat painful urination[]. An infusion of the inner bark has been used as an eye wash for sore eyes[].

Agroforestry Uses:

Fraxinus species in general are gross feeders with an extensive, fibrous root system, which makes transplanting easy, but means that other species will often not grow well if planted nearby, especially if they are shallow rooted[],

Other Uses

Logs of wood can be beaten with mauls to separate the growth layers, these layers can then be cut into strips and woven into baskets[].

A blue dye can be obtained from the bark[].

Wood - not strong, rather soft, durable, heavy, tough, coarse-grained, easily separated into thin layers. It weighs 39lb per cubic foot. Largely used for making furniture, cabinet making, interior finish and veneer[, , , , , ]. The wood makes a good fuel, it does not crackle or shoot sparks like many other woods[]. If the wood is soaked in water and then pounded, it separates easily into thin sheets[]. These sheets have then been used to make woven baskets, barrel hoops, chair seats etc[].

Propagation

The seed is best harvested green - as soon as it is fully developed but before it has fully dried on the tree - and can then be sown immediately in a cold frame[]. It usually germinates in the spring[]. Stored seed requires a period of cold stratification and is best sown as soon as possible in a cold frame[]. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in a cold frame for their first winter. Plant them out into their permanent positions or a nursery bed in late spring or early summer of the following year.
If you have sufficient seed then it is possible to sow it directly into an outdoor seedbed, preferably in the autumn. Grow the seedlings on in the seedbed for 2 years before transplanting either to their permanent positions or to nursery beds.