Definition
Heterosporous describes plants that produce two different types of spores: microspores and megaspores. Microspores develop into male gametophytes, which produce sperm cells. Megaspores develop into female gametophytes, which produce egg cells. This is an evolutionary step towards seed production. Heterospory is found in some ferns and all seed plants. It provides greater genetic diversity compared to homosporous plants. Think of it as plant reproduction having "male" and "female" versions.