Sporopollenin

Sporopollenin is a biological polymer found as a major component of the tough outer (exine) walls of plant spores and pollen grains.

The exine layer is often intricately sculptured in species-specific patterns, allowing material recovered from (for example) lake sediments to provide useful information to palynologists about plant and fungal populations in the past.

[5] Analyses have revealed a complex biopolymer, containing mainly long-chain fatty acids, phenylpropanoids, phenolics and traces of carotenoids in a random co-polymer.

[5] In 2019, thioacidolysis degradation and solid-state NMR was used to determine the molecular structure of pitch pine sporopollenin, finding it primarily composed of polyvinyl alcohol units alongside other aliphatic monomers, all crosslinked through a series of acetal linkages.

[7] Electron microscopy shows that the tapetal cells that surround the developing pollen grain in the anther have a highly active secretory system containing lipophilic globules.