Final answer:
The plant structure in lower plants that produces gametes is called gametangia.
Step-by-step explanation:
The plant structure in lower plants that produces gametes is called gametangia. In nonvascular plants such as mosses, liverworts, and hornworts, the gametophyte plant produces archegonia, which produce eggs, and antheridia, which produce sperm. These structures are typically found in the midst of modified 'leaves' at the ends of stems or branches.