Species At Risk

Blue Ash

(Fraxinus quadrangulata)

Special Concern

Blue Ash
Blue Ash occurrences map


The Blue Ash is a medium-sized tree with a straight, slender trunk supporting a narrow, rounded crown. Blue Ash grows 15 to 20 metres tall and the trunk is 15 to 25 centimetres in diameter. The bark is greyish and scaley. The leaves are opposite and compound, each with five to 11 leaflets. The leaflets are elongated, oval in shape, and have coarsely toothed edges.

Blue Ash grows quickly and can live 125 to 150 years.

Action we are taking:


The range of Blue Ash extends from southwestern Ontario south to Oklahoma and Georgia. In Canada, it occurs only in southwestern Ontario, at the northern limits of its range, where about 56 occurrences are known.


In Ontario, Blue Ash grows in deciduous floodplain forests, and along sandy beaches and on limestone outcrops associated with Lake Erie.


Historically, forest removal was the main cause of the decline of this species in Ontario. Harvesting of large seed-producing trees may also have contributed to local declines. More recently, the invasive beetle, Emerald Ash Borer, has been a threat to this and other ash species. There is some evidence that Blue Ash is at lower risk to Emerald Ash Borer attack. In tests of both feeding preference and choice of egg-laying locations, a number of studies found it to be less attractive to Emerald Ash Borer than Green or White Ash (Haack et al. 2005, Anulewicz 2006, Pureswaran and Poland 2009). But with the eventual loss of these alternative hosts, it may face severe impacts.


Blue Ash is listed as a species of Special Concern under Ontario’s Endangered Species Act. Although species of Special Concern do not receive legal protection under this act, some populations of this species are protected in national and provincial parks. Most of the remaining trees in Ontario are on private land.

What You Can Do to Help the Blue Ash

  • The Ministry of Natural Resources tracks species at risk such as the Blue Ash. You can use a handy online form to report your sightings to the Natural Heritage Information Centre. Photographs with specific locations or mapping coordinates are always helpful. nhic.mnr.gov.on.ca
  • Report any illegal activity related to plants and wildlife to 1-877-TIPS-MNR (847-7667).
  • Private land owners have a very important role to play in species at risk recovery. You may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats.
  • Volunteer with your local nature club or provincial park to participate in surveys or stewardship work focused on species at risk.
  • The Carolinian forests of southern Ontario support an amazing diversity of plants and wildlife, including many species at risk. Carolinian Canada is working to help recover species at risk and their habitats. For more information, visit: www.carolinian.org/SpeciesHabitats.htm.
  • Invasive species seriously threaten many of Ontario’s species at risk. To learn what you can do to help reduce the threat of invasive species, visit: ontario.ca/invasivespecies; www.invadingspecies.com; www.ontarioinvasiveplants.ca; and, www.invasivespecies.gc.ca.

Did you know?

The species' scientific epithet, quadrangulata, refers to the tree’s distinctive four-angled twigs. Blue Ashes are also called Four-angled Ash.

Did you know?

Blue Ash is named for the dye which can be extracted by mashing and cooking the inner trunk bark. It was used by First Nations and early European settlers.

Did you know?

Because of its dense wood, Blue Ash was prized for speciality uses such as tool handles.

Did you know?

Ash trees belong to the same family as olive trees and the familiar forsythias and lilacs of gardens.

Did you know?

Blue Ash is sometimes planted as an ornamental shade tree.

The Endangered Species Act

Contact your local ministry office

Often the best source of local information on species at risk is your nearest ministry office. Call with your questions or concerns.