Why do tiny water droplets appear on the tips of grass and leaves early in the morning?
At night transpiration nearly stops, but the roots keep actively absorbing water and minerals, building up root pressure.
At night transpiration nearly stops, but the roots keep actively absorbing water and minerals, building up root pressure. This gentle pressure forces excess water out through special pores at the leaf margins (hydathodes) as liquid droplets — a process called guttation. It's not dew (which is condensed atmospheric moisture); guttation water comes from inside the plant, pushed out by root pressure.
Key point
Root pressure at night forces water out through hydathodes as droplets (guttation).
Common mistake
confusing guttation droplets with dew from the air.
Memory tip
guttation = water pushed out from inside by root pressure (not condensed dew).
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