ELEGANT ENGINEERING. “In some flowers, for example in Oenothera spp., the sepals are connected by a zipper‐like mechanism whereby cells at the sepal margins are tangled. Due to the force of the growing petals this entanglement is broken and the petals are suddenly released. In several other species the sepal margins are tightly held together by ridges, which also delay opening until the growing petals overcome their resistance. This also results in rapid opening.”
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