when do leaves give off excess water?

Answer 1

At night, transpiration usually does not occur because most plants have their stomata closed. When there is a high soil moisture level, water will enter plant roots, because the water potential of the roots is lower than in the soil solution. The water will accumulate in the plant creating a slight root pressure. The root pressure forces some water to exude through special leaf tip or edge structures, hydathodes, forming drops. Root pressure provides the impetus for this flow, rather than transpirational pull. THis is called Guttation.

Guttation fluid may contain a variety of organic compounds, mainly sugars, and mineral nutrients, and potassium.

On drying, a white crust remains on the leaf surface.

If high levels of nitrogen appear in the fluid, then that is a sign of fertilizer burn. Excess nitrogen must be leached from the soil by addition of large quantities of water. This may result in water pollution, but is the best way to restore soil fertility.

Guttation is not to be confused with dew, which condenses from the atmosphere onto the plant surface.

Answer 2

When cellular respiration is performed, glucose (C6H12O6) is combined with 6 molecules of O2 and energy is made, and from the leftovers, we get 6CO2, and 6H2O. This excess water drips out the stoma at the bottom of the leaves. Stoma are gaps between cells that allow water to drip out

Answer 3

Excess water is given off by guttation - forming a drip at the end of the leaf.