Topic
Plants
5 articles
Biology
Why does a cut apple turn brown?
A whole apple sits in the fruit bowl all week and looks the same on Sunday as it did on Monday. Cut one at breakfast and it is the color of weak tea by lunchtime. Nothing was added to it.
Biology
How does a young sunflower follow the sun?
A sunflower has no muscles and nothing inside it that moves. A young one still swings its head halfway across the sky each day — and swings back overnight, in the dark.
Biology
How does a tree lift water to its highest leaf?
The tallest tree alive is taller than a thirty-story building, and the leaves at the very top stay wet all day. No pump ever built can raise water a tenth of that far.
Biology
Why do some leaves turn red before they fall?
The yellow in an autumn leaf was hiding under the green all summer long. The red was never there at all. A tree builds that color from scratch, in the last two weeks of a leaf it has already decided to drop.
Chemistry
Why do onions make you cry?
A whole onion can sit in the kitchen for a month without bothering anybody. Cut it, and within seconds something invisible has crossed the room to your eyes. It was not inside the onion a moment earlier.