Anther diversity and function in Verticordia DC. (Myrtaceae)

Anther form and structure across the taxonomic groups in Verticordia were e xamined. The three anther types which were recognised rectangular, oblong a nd saccate, accord well with the three subgenera into which the genus has b een divided. The sporogenous part of the anther has a fairly typical angios perm anatomy. However in many species there is a small or large gland in th e upper filament/connective which contains lipidic contents. The anatomy of this structure is based on that of the oil glands which are ubiquitous in Myrtaceae primary tissues. However the gland is usually much larger than th ese and is schizolysigenous in origin. Evolutionary development of the anth ers in the genus is related to pollination systems and the development of s econdary pollen presentation from the upper style in some groups. Anther gl ands may have originally had a protective function for the sporogenous tiss ue. However in different groups the function has changed or the gland has d isappeared. In some species in subgenus Chrysoma (which does not have secon dary pollen presentation) the gland contents seem to be an additional food source for pollinators. In other groups, with the development of secondary pollen presentation the protective function has become redundant and anther glands have either disappeared or produce contents which have become part of the process of pollen dispersal.