How do some grasses pollinate themselves without opening their flowers?

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wild rice — Poaceae Wild rice (*Zizania aquatica*).

In more than 300 grass species, some florets are cleistogamous, meaning they remain confined and do not open at flowering, which enforces self-pollination.1

This process typically occurs because the spikelets are retained within the leaf sheaths, preventing them from opening. In a few specific cases, such as Amphicarpum purshii (commonly known as peanutgrass), some spikelets are produced on stems that grow directly into the soil, where they are buried and pollinated before flowering even begins. This strategy serves as an extreme method for ensuring reproduction, particularly when environmental conditions might otherwise hinder cross-pollination.12