hydathode A pore found in the epidermis of the leaves of certain plants. Like stomata, hydathodes are surrounded by two crescent-shaped cells but these, unlike guard cells, do not regulate the size of the aperture. Hydathodes are used by the plant to secrete water under conditions in which transpiration is inhibited; for example, when the atmosphere is very humid. This process of water loss is called guttation.

hydathode A modified stoma, usually on a leaf, which remains open and secretes water during guttation.