Why do dandelions close up at night?
Think of a sunny morning in the park, with bright yellow dandelions dotting the grass. Run your fingers over one and feel its soft petals tickle your skin. It looks like a little sun sitting in the green.
Now picture the same grass in the evening, just before bedtime. Every dandelion has folded into a tight green bud, as if it had never bloomed at all. So why do dandelions close up at night?
All day long, a dandelion holds its petals wide open to the sun. Its bright yellow face lets bees spot it from far away. Bees zoom down and land right in the middle of it.
As a bee wiggles around, it gets dusted with pollen, the soft yellow powder that a flower makes. Bees eat some of it and carry some along to the next flower, and that helps flowers make seeds. So a dandelion keeps its pollen fresh for its visitors.
In the evening, the sun sinks low and the light grows dim. The air turns cooler, and the bees fly home to rest. Now no visitors will come for the pollen until morning.
Later in the night, dew will settle on everything in the park. Grass blades and leaves will end up covered in drops of water. What do you think the dew would do to the pollen if a dandelion stayed wide open?
The dew would soak the pollen and turn it into wet, sticky clumps. Wet pollen spoils, and the bees could not use it the next day. A dandelion has a clever way to stop that from happening.
A dandelion has no eyes, yet its petals can feel the light fading and the air cooling. That change is its signal to get ready for the night. So, long before the dew comes, the flower begins to close.
The outer side of each petal grows just a bit, and that bends the petal up and inward. Then the green leaves underneath fold around the petals like a snug sleeping bag. Inside, the pollen stays dry and safe all night.
Here is our key word: pollen. When the light fades and the air cools, a dandelion folds its petals shut to keep the night dew off its pollen.
Sleep tight, and may you feel as cozy as a dandelion tucked in for the night.
