NOTES: Polygamodioecious: predominantly dioecious (male and female flowers on separate plants [i.e., unisexual flowers]), but with individual plants producing bisexual flowers. Inner bark turns blue when exposed to air and was used to make dye. Square stems. MAD BUCK mnemonic (Maple, Ash, Dogwood, and Buckeye) useful for remembering Ohio's four native trees with opposite leaves/branching.