Pollen Ontogeny inVictoria(Nymphaeales)

Abstract

Premise of research. Water lilies (Nymphaeales) make up one of the oldest independent lineages of angiosperms. The giant water lily, Victoria, exhibits pollination and floral traits that are derived within Nymphaeales. Specialization in pollination and floral biology is often reflected in pollen traits, and in Victoria, this is evidenced by the production of permanent tetrads. Compound pollen has evolved many times across the angiosperm phylogeny, but compound pollen development has been investigated in only a few taxa, and the degree of developmental variation in microspore cohesion is unknown. This article comprehensively characterizes the pollen ontogenetic sequence in Victoria for the first time.Methodology. Floral buds of Victoria amazonica, Victoria cruziana, and Longwood hybrid were field collected. Anthers at the sporogenous, microspore mother cell, tetrad, “free” microspore, and mature pollen grain stages were studied using combined LM/SEM/TEM.Pivotal results. Microspore cohesion in Victoria diff...