Inaperturate pollen in monocotyledons

Inaperturate pollen is widespread in the monocotyledons, includes a diverse range of forms, and has arisen independently numerous times. Evidence for this comes from the phylogenetic distribution of inaperturate pollen and al so from developmental and structural differences. There is no correlation b etween the production of inaperturate grains and either microsporogenesis t ype or tapetum type. Inaperturate pollen has phylogenetic significance with in some groups, e.g., in Zingiberales, Liliales, and some Asparagales. Char acter states for inaperturate pollen are presented. It can broadly be divid ed into two types, "omniaperturate" and "functionally monoaperturate," base d on the thickening of the intine. The characters of omniaperturate pollen are adaptations that potentially increase the germination efficiency of the pollen. Both types sometimes occur in environments where pollen is not sub ject to desiccation and, thus, may remain viable with reduced exines.