1. Leaflets 5–9, the terminal one distinctly larger than those of lowest pair; pith of year-old twigs continuous; staminate aments peduncled in groups of 3.
1. Leaflets (9–) 11–19, the terminal one usually about equal to those of lowest pair, or smaller; pith of year-old twigs becoming chambered (separating into thin plates and cavities); staminate aments sessile or nearly so.
All species found in Juglandaceae
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. April 29, 2017. http://michiganflora.net/family.aspx?id=JUGLANDACEAE.