an inert, tough polymer forming the resistant outer coat of a pollen grain or spore.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
An organic polymer that is extremely resistant to degradation. Pollen grains and many kinds of spores have a protective outer coating of sporopollenin, which is so durable that microfossils of sporopollenin are found in rocks over 500 million years old.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.