exine

These grains are monosulcate and have reticulate-columellar exine structure; Couper and other early authors (e.g., Brenner, 1963; Doyle, 1969) described the columellae as varying from free to fused at their heads to form a tectal reticulum, but SEM studies showed that they are typically reticulate (Doyle et al., 1975; Hughes et al., 1979).

Differences between the spores of the two species are found in the exine. In A.

Homologs in other plants of most of these genes have been associated with the process of pollen wall development, such as suberin biosynthesis [43, 44], cutin biosynthesis [45-47], pollen sporopollenin biosynthesis [48], and pollen exine formation [49-51].

Brassicaceae is a stenopalynous family, the pollen grains usually tricolpate, with a reticulate exine (Abdel-Khalik, 2002).

Pollen is surrounded by a complex protective outer membrane called exine, that is characterized for being resistant and firm, and composed of Sporopollenin, which are biopolymers as cutin (composed of fatty acids to protect the cell surface), suberin (polymer of long-chain fatty acids) and lignins (phenolic compounds) (Zuluaga et al., 2014).

Common size class was mediae, exine sculpture was reticulate and symmetry was bilateral.

Also, Mert (2009) investigated the pollen length pollen width intine and exine thickness of six cornelian cherry (Cornus mas L.) cultivars.

Exine architecture and function in some Lythraceae and Sonneratiaceae.