Labellum vasculature in some monocotyledonous taxa

The vasculature and structure of the labellum are diagnostic and highly significant across monocotyledonous taxa. This study examined the floral vasculature of seven taxa from Cannaceae, Marantaceae, Zingiberaceae (Zingiberales), and Orchidaceae (Asparagales) using light microscopy (LM) to elucidate and characterize the nature and structure of the labellum in selected monocot taxa. The obtained data indicated that the labellum vasculature of Dendrobium nobile (Orchidaceae) was significantly different from that of the other examined taxa. The labellum of Dendrobium nobile was supplied by three separate vascular bundles: one posterior inner bundle and two postero-lateral bundles, corresponding to the median and marginal regions of the labellum. In Canna × hybrida and C. indica (Cannaceae), the labellum vasculature incorporated two bundles: one derived from the carpellary dorsal trace and another from the antero-lateral carpellary septal trace. The floral vasculature of Maranta leuconeura (Marantaceae) showed that the labellum was supplied by a single carpellary septal trace, which subsequently divided to form median and marginal bundles. For Alpinia zerumbet and Hedychium coronarium (Zingiberaceae), the labellum was supplied by three distinct vascular bundles: two antero-lateral carpellary septal bundles and one anterior carpellary dorsal bundle.