Plants use photosensitive internal cellular clocks to detect the length of days. When they sense the shorter days of autumn, the clocks activate genes that signal the plant to produce seeds and drop its leaves. When the clocks sense longer days in the spring, the plants grow back their leaves, along with flowers or fruit. Biological clocks help plants prepare for sunrise by raising their leaves, tilting them toward the sun, and preparing their internal factories to perform photosynthesis, converting sunlight into nutrients. At night, clocks orchestrate the opening and closing of leaf pores and
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