CYCLIC INVASION OF TAPETAL CELLS INTO LOCULI DURING MICROSPORE DEVELOPMENT IN NYMPHAEA COLORATA (NYMPHACEAE)

Abstract

In work with Nymphaea colorata Peter three distinct intervals were recorded during which tapetal cells (protoplasts) protruded into anther locules either as bridges and partitions or as invasive cells between or around tetrads of microspores. Before these intervals and between and after them, tapetal cells, while variable in shape, were noninvasive. Observations were based on sections of over 60 fixed and epoxy‐embedded anthers covering the relatively brief interval from the end of meiosis through the vacuolate microspore stage. The progression of development, from early microspore stages through the microspore vacuolate period, is illustrated by transmission electron micrographs showing change in proexine and exine size and complexity. Our results indicate cycles of tapetal cell differentiation and dedifferentiation in this species.