How do cleistogamous legume flowers pollinate without opening?

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Yellow partridge pea — Fabales A flowering stalk of yellow partridge pea (*Chamaecrista fasciculata*) in the eastern United States.

In the context of the plant order Fabales, cleistogamous flowers are a specialized reproductive adaptation where the flower remains closed, thereby preventing the entry of external pollinators such as insects.123

Because these flowers do not open, they enforce self-pollination within the closed floral structure. In many legumes, this process serves as an effective mechanism for obligate self-fertilization, allowing the plant to fix and maintain successful genetic strains. While many legumes also produce chasmogamous (open) flowers to facilitate cross-pollination and promote evolutionary diversity, the cleistogamous flowers ensure seed production even when environmental conditions are not conducive to outbreeding or when pollinators are scarce.123