The very resistant and refractory organic substance of which the exine and perine of pollen and spores are composed. Sporopollenin gives the palynomorph its extreme durability, being readily destroyed only by oxidation or prolonged high temperature. It is a probably a high-molecular-weight polymer of carotenoids.

an organic polymer that makes up the coat of a pollen grain or spore; sporopollenin is extremely resistant to degradation

Sporopollenin is a major component of the tough outer (exine) walls of spores and pollen grains. It is chemically very stable and is usually well preserved in soils and sediments. The exine layer is often intricately sculptured in species-specific patterns (see image at right), allowing material recovered from (for example) lake sediments to provide useful information about plant and fungal populations in the past.