Pollen morphology of Mourera (Podostemaceae)

The pollen morphology of Mourera (Podostemaceae) was analysed with the aim of providing detailed descriptions of pollen for all species of the genus. Pollen grains were obtained from anthers of flower buds, acetolysed, and examined using light and scanning electron microscopy. The pollen grains are monads, small or medium sized, prolate in shape, with a circular or subcircular amb. Pollen grains are tricolpate, and the colpus was variously ornate and has distinctive ornamentation between apertural and non-apertural regions. The exine is thin and microechinate with supratectal spines in all species. In M. fluviatilis, M. monadelpha and M. schwackeana the surface has inconspicuous spines without delimited basis; in M. alcicornis, M. aspera, M. elegans and M. weddelliana, the surface has spines at the apices of mamiloid elements', with a wide base of spines individualised and well defined. Hierarchical cluster analysis (HCA) was used to divide the main pollen taxa into three groups based on pollen morphology. Statistically distinctive taxa were identified using principal component analysis (PCA). Pollen analysis revealed a significant overall correspondence between pollen variations amongst species of Mourera and phylogenetic patterns.