Did you know that we monitor an array of species at risk on our protected farms across Ontario? One of our favourite species that calls some of these protected farms home is the Butternut Tree, provincially listed as endangered!

The Butternut Tree is also known as the White Walnut tree. It is a medium-size deciduous tree found in northern, central, and eastern Ontario. If trying to locate one, start with checking out areas where the soil is moist, non-acidic, and/or limestone-based although they can also be found in drier areas with lots of open sun. If you come across a young tree, their bark is ash grey and smooth, whereas an older tree will have wide, diamond pattern ridges. It has compound leaves in groups of 11-17, similar to those of Sumac, however these are stalkless and have a fuzzy underside. Come fall, when leaves start to drop, a hairy fringe (that looks like a moustache) is left behind at the leaf scar.

However, of the easiest ways to identify a Butternut is by their fruit! In comparison to a Black Walnut (a close relative of the Butternut), the Butternut’s fruits are oval rather than round. The Butternut’s fruit are also sticky to the touch, and actually smell like citrus too! 1 Using these identification details can help you distinguish a Butternut Tree from other hardwood species and especially from other Walnut species that hold an uncanny resemblance.

The oblong fruit of the Butternut vs. the round fruit of the similar Black Walnut.

Unfortunately, there has been a rapid decline in the population of this beautiful native tree primarily due to a fungal disease called Butternut Canker that infects and kills healthy Butternut trees. “The fungus enters through exposed areas, forms elongated patches called cankers and the cankers expand to cut off the flow of water and nutrients. As the disease spreads, different areas of the tree die off, and the cankers release a blackish fluid.”2

In order to help with the conservation of this species, we must help current recovery initiatives such as the Ontario Butternut Recovery Program by protecting any existing Butternut Trees. Using the identification details described above, landowners can help identify whether they may have a Butternut Tree on their property.

If you have a healthy Butternut Tree on your property that doesn’t have signs of a canker, or if the cankers have been callused over, it may be resistant to the detrimental Butternut Canker fungus! This means that it could be valuable for grafting and propagating new specimens, which could help support this species long-term! The best step forward would be to contact the Forest Gene Conservation Association to set up an assessment and a genetic test will be conducted if they believe it to be so. For more information, please visit https://fgca.net/species-conservation/trees-in-trouble/butternut/ .


  1. Forest Gene Conservation Association. (2010) A Landowner’s Guide to Butternut and Butternut Canker in Ontario. https://fgca.net/wp-content/uploads/2012/07/Butternut_Brochure-2010.pdf
  2. Forest Gene Conservation Association. (2012) Butternut Tree Ontario Species at Risk: A Landowner’s Resource Guide. https://fgca.net/wp-content/uploads/2012/07/Butternut_LO_Guide.pdf