Species At Risk

American Chestnut

(Castanea dentata)


American Chestnut
American Chestnut occurrences map


The American Chestnut is a tall deciduous tree that formerly reached about 30 metres in height; however, trees in Ontario are now typically only five to 10 metres tall. The bark is dark grey-brown and cracks with age. Leaves are mostly hairless, 15 to 30 centimetres long and five to 10 centimetres wide at maturity, with coarsely and sharply serrated edges and a long pointed tip. Chestnut trees have both male and female flowers but cannot self pollinate. The fruit is a spiny bur-like husk enclosing one to five edible nuts. Small mammals and birds distribute, store and bury the nuts.


The American Chestnut has almost disappeared from eastern North America due to an epidemic caused by a fungal disease called the chestnut blight (Cryphonectria parasitica). In Canada, the American Chestnut is restricted primarily to southwestern Ontario. Based on information available in 2004, it was estimated that there are 120 to 150 mature trees and 1,000 or more small, young trees in the province.


The American Chestnut prefers dryer upland deciduous forests with sandy, acidic to neutral soils. In Ontario, it is only found in the Carolinian Zone between Lake Erie and Lake Huron. The species grows alongside Red Oak, Black Cherry, Sugar Maple, American Beech and other deciduous tree species.


Chestnut blight has had a devastating impact on the American Chestnut. The accidental introduction of this fungus to North America from Asia in the early 1900s killed 99 per cent of American Chestnut trees within about 30 years! This disease continues to be the overwhelming threat to American Chestnut throughout its range. There is no proven natural resistance to the disease found in the remaining population. Fortunately, the disease primarily kills the top of the tree, often leaving living root systems. Diseased trees respond by re-sprouting from the base of the dead stumps. The existing population primarily persists as saplings and trees that grow from these stumps and the odd tree that germinates from viable seeds. Habitat loss due to forest clearing and damage to trees during logging operations are additional threats.


American Chestnut is protected under Ontario’s Endangered Species Act and the federal Species at Risk Act.

What You Can Do to Help the American Chestnut

  • The Ministry of Natural Resources tracks species at risk such as the American Chestnut. 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 recovery. If you find Amercian Chestnut on your property, you may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats.
  • The Canadian Chestnut Council is a scientific and charitable organization dedicated to the protection and recovery of American Chestnut in southern Ontario. Find out more about this organization at www.canadianchestnutcouncil.org.
  • Volunteer with your local nature club or provincial park to participate in surveys or stewardship work focused on species at risk.
  • Pollinators, such as bees, are in steep decline across the globe and they play a key role in the survival of many of Ontario’s rare plants. For information on how you can help scientists monitor pollinator populations in Ontario visit: www.seeds.ca/proj/poll.
  • 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?

When they were abundant, the edible American Chestnuts provided an important source of food for a variety of animals and birds, as well as people.

Did you know?

Aboriginal people used the American Chestnut for treating numerous ailments (from coughs and dermatitis to heart trouble), as a staple food and beverage, to build shelters, for firewood and as a source of dye. Early settlers soon realized the many important uses of this tree.

Did you know?

American Chestnut flowers are pollinated by insects. Squirrels scatter and plant the seeds when they bury them.

Did you know?

Don’t confuse the rare American Chestnut with the cultivated chestnuts found in Ontario. These include Spanish Chestnut (C. sativa), Chinese Chestnut (C. mollissima) and Japanese Chestnut (C. crenata). All of them have varying degrees of hairiness on the lower leaf surfaces. Hybrids between these species and American Chestnut are known and difficult to identify.

Did you know?

Horsechestnut (Aesculus hippocastanum), is a very different tree planted in urban areas of southern Ontario. It has five leaves in a semi-circle formation and a spiny fruit containing one large shiny nut.

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.