Floral anatomy of Thomandersia (Lamiales), with particular reference to the nature of the retinaculum and extranuptial nectaries

摘要: Thomandersia is an isolated genus that currently unplaced in Lamiales. In the past it has been classified Acanthaceae or Pedaliaceae, on basis of intuitive assessments a limited number morphological characters. Recent molecular sequenced-based phylogenies have suggested relationship to Bignoniaceae, Schlegeliaceae Verbenaceae. Here we present new observations floral anatomy Thomandersia, with particular emphasis structure retinaculum, character shared Acanthaceae, and calyx nectaries, which may be other families The anatomical characters are discussed context recent phylogenetic hypotheses for Lamiales, aim identifying potential primary secondary homologies between related We find shares range each might sister-group, some these must therefore homoplastic. particular, if topology based sequence data correct, retinacula homoplastic represent example parallel evolution. © 2005 Linnean Society London, Botanical Journal Society, 2005, 149, 469–482.