Stigma structure and variation in Bromeliaceae—Neglected taxonomic characters

Abstract

Three distinct types of stigma architecture, designated as “simple-erect,” “conduplicate-spiral”, and “convolute-blade” were identified for Bromeliaceae. Structure of the conduplicate-spiral and convolute-blade stigma types is highly complex and previously unreported. Stigma morphology, largely neglected in Tillandsioideae until recently, promises to yield new characters valuable in interpreting systematic relationships in this subfamily. Data indicate that the putatively plesiomorphic state (simple-erect) is retained in some members of all three subfamilies. We found convolute-blade-type stigmas only in Tillandsioideae, though not in all members of the subfamily. Our sample indicates that Tillandsioideae stigmas are more like those of Pitcairnioideae than of Bromelioideae, which is consistent with Smith’s hypothesis of phylogenetic proximity of Tillandsioideae and Pitcairnioideae. Stigma architecture is proving to be a rich source of data for phylogenetic reconstruction and for classification at several infrafamilial levels.