Guttation is the secretion of xylem sap on the edges or tips of leaves of certain vascular plants, such as grasses. Because leaves can only soak up a finite amount of water, excess water is secreted from the roots, through the xylem and out through the hydathodes, or water glands. These structures are found on the edges of a plant’s leaves.
During dry conditions, excess water evaporates into the atmosphere. In cooler and more humid climates, however, the excess water cannot evaporate. Instead, guttation occurs and the excess moisture is observable on the leaf. Guttation is common with high moisture levels in soil. Water can flood a plant’s root system when the water potential of the root system is lower than the soil’s moisture level. The excess water accumulates in the plant and puts pressure on the roots. Under pressure, the root cells push water-carrying xylem upwards and out of the leaves through the hydathodes.
Similar to all living organisms, plants must transport moisture and nutrients throughout their cells. Plants utilize phloem and xylem as the primary mediums for transport. Roots soak up water and pull in nutrients from the soil, then transport the nutrients into the plant’s stems and leaves through xylem. The leaves consume light energy to create food and chemical energy for the plant system. The energy then travels downward into the roots via the phloem.