Sentence:  In plants, the ability to recognize self from nonself plays an important role in fertilization, because self-fertilization will result in less diverse offspring than fertilization with <WSD>pollen</WSD> from another individual. 
Meaning of the word marked with <WSD> tags:  A fine granular substance produced in flowers. Technically a collective term for pollen grains (microspores) produced in the anthers of flowering plants. (This specific usage dating from mid 18th century.)