The Butternut or White Walnut (Juglans cinerea) is a hardwood tree that ranges from eastern Canada west to Minnesota and as far south as Mississippi. Unfortunately, this tree is being killed throughout its growth range by Sirococcus claviginenti-juglandacearum, a fungus most likely introduced from outside of North America. The sapwood ranges from white to light grayish brown in color and is rarely more than a single inch wide. In contrast, the heartwood is a lustrous light chestnut-brown and frequently variegated with pigment.

More than 90 percent of all butternut trees in Ontario and western Quebec are now infected with the deadly canker. This disease has led to the butternut tree being placed on the endangered plant listing in the United States. Although use of lumber from this tree is restricted, wood from the butternut has been used for furniture, cabinets, instrument cases, interior trim, paneling, woodenware, toys, and novelties.

Microscopic examination of iron-alum hematoxylin and safranin stained thin sections (see the digital images presented above) reveal a semi-ring porous wood having simple perforation plates. Tyloses are fairly abundant in the sections and unstoried rays are one to four seriate and homocellular. Vessels are large, but few in number, with inter-vessel pits being 8 to 16 micrometers in diameter and orbicular to oval or angular (through crowding) in shape. Fiber tracheids are thin-walled with a medium to very coarse texture.

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