Several years ago Professor A. B. Noble of the English Department of Iowa State College called my attention to a peculiar walnut which he thought might be hybrid between the butternut (Juglans cinerea) and the black walnut (Juglans nigra). He again called my attention to the same tree last fall, in October, 1917.
Proceedings of the Iowa Academy of Science
©1918 Iowa Academy of Science, Inc.
Pammel, L. H. and King, Charlotte M.
"A Variation in the Black Walnut,"
Proceedings of the Iowa Academy of Science, 25(1), 241-247.
Available at: https://scholarworks.uni.edu/pias/vol25/iss1/26