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the exudation of water droplets by plant leaves, occurring when more water is absorbed by the roots than is evaporated by the leaves. It is observed mainly at night, in the early morning, or when plants are placed in a humid atmosphere; it is often observed in young sprouts, such as those of grains, whose root-system development overtakes the development of the evaporative surfaces of their leaves. The drops of water are secreted through water stomata under the action of root pressure, by the force of water pressing into the stems and leaves. Guttation is a physiological process connected with the life processes of the plant; if wheat sprouts are placed under a cone inside of which there is chloroform vapor, guttation ceases. Secretions of guttation always contain a number of mineral substances. Evidently guttation rids the plant of excess salts, mainly calcium.