imageDew on a Equisetum fluviatile Luc Viatourjpg size rowsize titleGuttation texttitleGuttation captionAn example of guttation the appearance of drops of xylem sap on the tips or edges of leaves of some vascular plants on an Equisetum 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 Guttation is not to be confused with dew which condenses from the atmosphere onto the plant surface creditPhoto credit