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Why do some Faboideae plants produce both open and closed flowers?
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Fabales
A flowering stalk of yellow partridge pea (Chamaecrista fasciculata) in the eastern United States.
Some plants within the subfamily Faboideae (also known as Papilionoideae) produce two distinct types of flowers to balance different reproductive strategies.1
- Chasmogamous flowers: These are typical, conspicuous flowers with petals that open, allowing for cross-pollination by insects or other pollinators. This outbreeding provides evolutionary diversity, which can help a species adapt to environmental changes or expand its range.21
- Cleistogamous flowers: These flowers do not open, and their parts are reduced, which enforces self-pollination by preventing the entry of insects. This mechanism of enforced inbreeding serves to fix and maintain successful genetic strains.21
By producing both types of flowers—often on the same plant—these legumes benefit from the flexibility of outbreeding while ensuring reproductive success through the reliability of self-pollination.1