Abstract:The flowers of Zingiberaceae have higher degrees of organ fusion and specialization with one functional stamen and two lateral subsidiary structures, which result in controversial explanations on the derivation and nature of the floral organs. However, the origin and course of the floral vasculature may provide credible evidence to understand the nature of floral structures. This paper reported the floral anatomy of Hedychium forrestii Diels with paraffin method. The floral vasculature of H. forrestii is described and the nature of labellum and petaloid subsidiary structures is discussed. The labellum is supposed to represent one member of the outer androecial whorl by the median bundle and two members of the inner whorl by its two lateral traces. While the two petaloid structures, the petaloid staminodes, receive vascular traces of two adaxial sets of carpellary dorsals, representing two inner androecial members. Present evidence is in support of the Thompson and Gregory’s view that the labellum is a triple structure in Zingiberaceae. As in other species of Zingiberaceae, the epigynous glands on the prolongation of the flower in H. forrestii are vascularized emergences of the ovary, which are of modified gynoplural nectary but not androecial member. Comparison with other species studied, the origin and course of floral vasculature are consistent in the tribe Hedychium, which indicated that homeosis played an important role in the evolution of the flower in Zingiberaceae.
