Sexual Dimorphism in the Flowers of Aegiphila odontophylla (Lamiaceae)

Little is known about the sexuality of the woody Neotropical genus Aegiphila. For a long time species of Aegiphila were thought to be heterostylous, but more recently it has been reported that a few species are dioecious and suggested that likely most Aegiphila are functionally dioedous. In this note, dioecy is confirmed in Aegiphila odontophylla from live plants in the Talamanca mountains in Costa Rica. Further, comparison of total flower size revealed that male and female reproductive structures are displayed at similar heights, likely resulting in accurate pollen uptake and delivery by pollinators. The length of the corolla tube as an estimate of flower showiness on the other hand was significantly different between male and female individuals. Male individuals had longer corolla tubes, suggesting a possible role for sexual selection in the evolution of floral dimorphism in this species.