Q. Why are my plant leaves dripping water?
I think you are observing a phenomenon known as guttation, in which specialized leaf tip glands occasionally release water droplets.
Many small plants possess glands that can emit a clear liquid. Although sometimes called "sap," guttation fluid is made up of water and a variety of organic and inorganic compounds.
The word guttation is derived from the Latin word gutta, meaning droplet. Excess moisture in the leaf normally transpires through stoma (minute holes in the leaf) and evaporates. Heat, wind, and dry conditions accelerate this evaporation. Under conditions of cooler temperature, still air, high humidity, or night, this evaporation slows or halts. Excess water accumulates at the leaf's tip.
This accumulation happens most often when soil is very moist. The plant roots absorb moisture from the soil, pushing it up through the plant's xylem (water-carrying tissue) until it reaches the leaves. As evaporation is not "pulling" the water out of the plant, the water inside the leaf has no place to go. Water pressure builds to a point where the plant is simply forced to release the liquid, exuding it fluid through specialized glands.
Guttation frequently occurs in tropical plants when high humidity inhibits the natural transpiration, which is simply the loss of water vapor inside the plant to the outside air.
For an illustrated example of guttation, see Missouri State University's Grape Guttation page.
For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service