Sentence:  In <WSD>plants</WSD>, 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 pollen from another individual. Many genes with reproductive roles also have antibacterial and immune functions, which indicate that the threat of microbial attack on the sperm or egg may be a major influence on rapid evolution during reproduction. 
Meaning of the word marked with <WSD> tags:  An organism that is not an animal, especially an organism capable of photosynthesis. Typically a small or herbaceous organism of this kind, rather than a tree.