The ultrastructure of mature Papaver dubium L. pollen grains

The mature pollen of Papaver dubium is bicellular. The exine is composed of a nexine, bacula and a perforated tectum. The vegetative cell contains numerous mitochondria, small vesicles and ribosomes. Spherosomes, plastids and larger vesicles are present in relatively smaller numbers. Plastids do not contain starch. Dictyosomes are very low in number. RER is extensively present and has a stacked configuration, while single RER cisterns are located along and close to the surface of the plasma membrane. The generative cell is spindle shaped with tail-like extensions, and it shows an undulating outline in transverse sections. Bundles of microtubules are present in the outward bends of the cell. The generative cell contains a reduced number of mitochondria, ribosomes, ER and vesicles, and it does not contain plastids.