Thymelaea hirsuta in Liguria: survival, reproduction and conservation problems

Thymelaea hirsuta (L.) End. is a circum-Mediterranean, subdioecious, evergreen shrub supposed to be an evolutionary example of the pathway from heterodichogamy to dioecy. However, discordant data concerning the pollination mechanism of the plant have been reported in different zones of the species range (France, Egypt and Italy). The present study, concerning three populations from the North Tyrrhenian Area, carries on anatomical alalysis of flowers, sex organ development, and unisexual flower differentiation. At the stage of pilose primordium all flowers are hermaphrodite and the future of these primordia then varies according to the sexual pathway followed by both the individual plant and flower. The embryo development often results in a degenerative process, whose causes are still unclear, justifying the very low percentage in seed germination recorded all over the species range. By considering also the difficulties in vegetative reproduction of the plant , it is very difficult to define conservation strategies in the North Tyrrhenian populations which show demographic decrease.