Structure and systematics of Hanguana, a monocotyledon of uncertain affinity

Abstract

Floral anatomy and some aspects of leaf and root anatomy of Hanguana are described for the first time and reviewed with respect to its systematic position in monocotyledons. Several characters support its placement in the commelinoid clade, including cell wall ferulates, silica bodies and tetracytic stomata with non-oblique cell divisions. Analysis of morphological data indicates that Hanguana is the sister taxon to Zingiberales. Characters supporting this association include spinulate inaperturate pollen, plasmodial tapetum type, mucilage-secreting intra-ovarian trichomes and modified septal nectaries. Gynoecial nectaries were present in male flowers (probably modified septal nectaries, as in some Zingiberales) and staminodial nectaries in female flowers examined.