Microsporogenesis variation in Codiaeum producing inaperturate pollen grain.

A study of microsporogenesis (the earliest stage of pollen ontogeny) was undertaken in seven cultivars of Codiaeum variegatum var. pictum, a eudicot species that produces inaperturate pollen grains. Microsporogenesis appears highly variable for the developmental events suspected to be implicated in the determination of aperture pattern. Most eudicots have tri-aperturate pollen grains and microsporogenesis is described as highly conserved in this clade. The observed burst of variation in C. variegatum therefore appears especially remarkable. A plausible hypothesis to explain the variation is that the pollen being inaperturate, the selective forces applying on the ontogeny of the aperture pattern are relaxed.