Many heartnut seedlings revert back to Juglans ailantifolia and not Juglans ailantifolia var. cordiformis. That is, their nuts will resemble the thick-shelled Japanese walnuts.

Some heartnut seedlings have a 70% chance of being just Juglans ailantifolia trees. Also those seedlings produced from the best heartnut parents will produce up to 90% heartnut offspring. Therefore we cannot 100% guarantee a true heartnut is produced.