noun. A water-excreting microscopic epidermal structure in many plants.

noun. A tissue, in the leaves of many plants, that contains microscopic pores through which water is excreted.

noun. a pore that exudes water on the surface or margin of a leaf of higher plants

"Even if the hydathode is treated with sublimate solution, all the conditions for mechanical filtration still remain: the earth has moisture which can be taken up by the roots so that root-pressure still exists."

pore  stoma  stomate