Pollen morphology in the trimeniaceae

Abstract

Piptocalyx macrurus Gilg & Schlechter, P. moorei Oliver and Trimenia neocaledonica Baker f. have disulculate, globose-elliptic or globose-spherical to globose-elliptic grains, with finely reticulate or rugulose (T. neocaledonica) structure. T. papuana Ridley has dimorphic pollen, with only one type on an individual plant, consisting of either globose-elliptic inaperturate grains, or globose-spherical polyforate grains. Both types have weakly rugulate structure. T. weinmanniifolia Seeman has globose-spherical polyforate pollen, with similar structure. Exine is tectate-columellate. In T. papuana and T. weinmanniifolia the innermost tectum, columellae and foot layer have a partly granular form. Whether this condition is primitive or derived, is not clear. All taxa have a lamellate endexine in non-apertural regions. It is suggested that either disulculate and polyforate pollen has evolved from inaperturate, or that there is a series disulculate → inaperturate → polyforate. Pollen morphology confirms the comparatively isolated position of the Trimeniaceae within the Laurales.