Evolutionary origin of a periodical mass-flowering plant.

The evolutionary origin of periodical mass-flowering plants (shortly periodical plants), exhibiting periodical mass flowering and death immediately after flowering, has not been demonstrated. Within the genus (Acanthaceae), which includes more than 50 periodical species, on Okinawa Island, Japan, flowers gregariously every 6 years. We investigated the life history of in other regions and that of closely related species together with their molecular phylogeny to reveal the evolutionary origin of periodical mass flowering.