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COSEWIC assessment and status report on the American Chestnut in Canada


Executive Summary

American Chestnut
Castanea Dentata

Species Information

American chestnut is a member of the beech family. It is the only species of chestnut native to Canada. It has elongate leaves tapered at both ends and large teeth along the margins. Flowers are arranged in catkins with numerous tiny male flowers and a cluster of several female flowers at the base of some of the catkins. When cross-pollinated with another chestnut tree by an insect pollinator, the female flowers develop into spiny bur-like fruits enclosing one to several chestnuts. This species once was a dominant tree in many areas of the eastern deciduous forests of North America, but has been greatly reduced by the introduction of the chestnut blight disease a century ago.



This species occurs throughout eastern North America from southern Maine to southern Ontario and Michigan, south to Georgia to Mississippi. Remnants of once large populations of this tree still survive across most of its historical range in southern Ontario as well as most of the states within its range to the south.



The typical habitat is upland deciduous forests on sandy acidic soils, occurring with red oak, black cherry, sugar maple and beech.



This species is a shade-tolerant forest tree needing a canopy cover for effective seedling establishment. It produces both male and female flowers on the same tree in late spring to early summer. It is insect pollinated and requires cross-pollination for seed set. Nuts are produced in the fall of the same year and are sought after by squirrels, chipmunks and large birds that also disperse the seeds beyond the parent trees.


Population Sizes and Trends

Remnant populations are rarely very large, typically single trees or small groups. It is estimated that there are currently 120-150 mature trees and 1000 or more smaller, non-reproductive individuals in Canada. It is inconclusive if the status has significantly changed since the mid-1980s.


Limiting Factors and Threats

The introduction of the chestnut blight fungus in about 1904 devastated populations of this species throughout its natural range, including its Canadian distribution in southern Ontario. Most individuals are stump sprouts that never reach fruiting size. Recovery planning has identified possible hybridization with Asian species in native stands as another potential threat.


Special Significance of the Species

American chestnut had a wide spectrum of uses by native peoples, from treatment of ailments to a staple food, to material for building and dyeing. Early settlers soon realized what an important tree this was and used it in similar ways. Its abundant production of nourishing nuts also was an important food for various mammals and birds of the forest.


Existing Protection

It is ranked by the Natural Heritage Information Centre (Ontario) as S2 (imperiled), but has not yet been given official provincial status.