| Dec 17, 2009

Back to HomeOutdoors in the Land O'Lakes - December 17, 2009 Walnuts of Ontarioby Steve Blight

As a high school student, I once made a project from two hardwoods, one dark and one light, which when glued up properly and turned on a lathe became a beautiful lamp. The attractiveness of the piece was much more because of the natural beauty of the woods, and not from any finely-honed woodworking skill on my part. The light wood was maple, and the dark wood was black walnut. Thus began a fascination with walnut trees that continues to this day.


It may come as a surprise to some people that two species of walnut trees are native to Ontario. The first is Black Walnut, a tree that grows in Ontario south of a line that runs roughly from Toronto to Sarnia, and throughout much of the eastern USA. It has been widely planted in areas further north. For example, it can be found growing in Ottawa, and is now beginning to reproduce naturally. Black walnut is best known for its heavy, hard, dark but easily worked wood. It grows as a medium to large tree, up to 30 meters (100 ft) tall, 120cm (4 ft) in diameter and 150 years old. It normally has a tall straight trunk with an open rounded crown. When growing in the open, it is a very attractive tree. Curiously, a toxic substance called juglone that leaches from fallen leaves and is exuded by its roots inhibits the growth of many broadleaved plants, including other walnut seedlings!

The other native walnut is the Butternut, or White Walnut as it called in some areas. The natural range of this tree extends further north than the Black Walnut, occurring in Canada in southern New Brunswick, Quebec and Ontario. It can be readily found in the Land O’ Lakes area, growing best on well-drained fertile soils on gradual slopes. It is generally a smaller tree than its cousin, growing up to 25 meters (80 ft) tall, 75 cm (30 inches) in diameter and 80 years old, although larger individuals can be found. Like the Black Walnut, the Butternut does not tolerate shade. Butternut wood is softer and lighter in colour than black walnut and is used in cabinetry and turnery.

Walnut trees are best identified by their long compound leaves consisting of up to 25 leaflets on a central stalk, and the large, hard-shelled nut covered by a thick green husk. Unlike so many of the nuts from our native trees, the nuts of both walnuts are edible. The trick is getting them out of the shell – the husks leave a deep greenish-brown stain on the hands, and the shells are really tough. One of my sources suggests getting the husk off by driving over the nuts repeatedly with a car, then cracking the shells with a sledge hammer and picking out the edible bits. My personal experience is limited to once cutting the husk off a butternut with a utility knife and cracking the shell with a framing hammer. The pieces that I salvaged from the resulting mess were quite tasty.

Unfortunately, the Butternut is becoming increasingly scarce across its full North American range because it is being attacked by a fungal disease called Butternut Canker. Trees affected by this fungus usually do not survive. As a result, the Butternut is listed as an endangered species under both federal and Ontario law. In one study I read, up to 85% of the Butternuts in one part of Vermont were killed over a period of about 15 years. However, some trees seem to have some resistance to the disease, so landowners are being advised not to cut down healthy Butternuts. The hope is that these healthy trees may produce seeds that grow into trees that are also resistant to the disease. Some conservation groups are identifying healthy Butternuts, gathering their seeds before the squirrels get them and growing seedlings for planting in appropriate places. Landowners with suitable locations for planting Butternuts may want to contact the Rideau Valley Conservation Authority for more information on this promising program. Fortunately Black Walnuts are not affected by this disease.

With any luck there will continue to be both Black Walnut and Butternut wood available for high school projects for new generations of budding woodworkers!

Please feel free to report any observations to Lorraine Julien at This email address is being protected from spambots. You need JavaScript enabled to view it.  or Steve Blight at This email address is being protected from spambots. You need JavaScript enabled to view it.

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