Genetics of Alternating Sexes in Walnuts (IMAGE) University of California - Davis Caption UC Davis graduate student Jeffrey Groh has discovered how walnut trees are able to produce flowers of different sexes at different times in the same season. The genetic mechanism is similar to sex determination in many animals. Pictured, Groh with a California black walnut tree on the UC Davis campus Credit Sasha Bakhter, UC Davis College of Biological Sciences Usage Restrictions May be used with acknowledgment. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.