You know those perfect people who just look beautifully dewy in 90 degree heat, instead of rocking salt-bedraggled hair and sweat-streaked makeup? I used to suspect them of being part Veela, but now I think they are plants. It turns out plants can sort of sweat — it’s called “guttation” — and go figure, they look gorgeous doing it.
Guttation happens when plants take in excess water from the soil, but don’t evaporate it through their stomata (or pores) because those close up at night. (Technically this evaporation, called transpiration, is more analogous to how people sweat — but it’s not as photogenic.) Water pressure in the roots forces some of the plant’s sap out through openings in the leaf edge or tip, so that it looks like the leaf is wearing a tiara.
Now that I think about it, though, hmm … the plant is taking in moisture, and there’s more than it can sweat it out through its pores, so it causes a slightly different substance to come out through a specialized opening. Is guttation plant pee?? In that case, I’m even more impressed that they look so damn good doing it.
Hat tip: Steve Silberman