The other parts constituting the wall of the grain are an inner layer, the intine, and an outer layer, the exine. |
Pollen grains possessing a much-reduced exine and elaborated intine are known to occur in 54 families of angiosperms and are nearly ubiquitous in Zingiberales. |
Acetolysis and treatment with NaOH are known to dissolve the exine of Xyridaceae pollen, thus only untreated grains were examined. |
For example, the top surface is analyzed to understand the ornamentation while the central images help to identify the cytoplasm or the exine thickness. |
Orbicules may be attached to the exine of the pollen grains. |
Clypeate grains are either functionally omniaperturate and have a thin exine and uniformly thickened intine or are porate with localized thickenings of intine. |