Plasmodial tapetum and pollen wall development inButomus umbellatus (Butomaceae)

This report describes the ultrastructural development of plasmodial tapetum and pollen wall of Butomus umbellatus . The tapetum contains extensive arrays of rough endoplasmic reticulum, vesicles from which are responsible for the formation of sporopollenin‐like bodies. The tapetum is also involved in the formation of other forms of sporopollenin precursors. Development of pollen wall continues after microspores are released from their callosic walls; they are then enclosed by plasmodial tapetum. The activity and products of the plasmodial tapetum show substantial correlation with pollen wall development, particularly ektexine formation. In B. umbellatus , the tapetum intrudes into the anther locule at early microspore stage. This timing of plasmodial intrusion occurs at a later stage of pollen development as compared to those in the advanced monocotyledons. We report the rough endoplasmic reticulum origin of sporopollenin‐like bodies and their occurrence in the plasmodial tapeta of B. umbellatus.