Scientific Name
Juglans ailantifolia v. cordiformis
The heartnut tree is a variety of Japanese walnut selected centuries ago in Japan for its distinctive heart-shaped nuts. The standard species produces less uniformly shaped nuts. The shells are relatively easy to crack, and the nutmeat can often be removed intact. It is considered very flavorful and is sometimes used for decorative purposes as well.
The compound leaves resemble those of butternut, reaching up to 24 inches long with 11 to 17 leaflets. Fall color is minimal, which helps distinguish heartnut and buartnut from the native North American butternut, which typically turns a brighter yellow. The species name ailantifolia reflects a resemblance of the leaves to those of tree of heaven (Ailanthus).
As it matures, the trunk remains a light gray and gradually develops ridges and furrows. Heartnut is rarely encountered in our region, and its ultimate size here is still uncertain, though it appears to be fully hardy. A Japanese walnut in Boulder, listed as a Colorado champion at 32 feet tall, gives some indication of potential size, though it is not known whether that tree is the heartnut variety.