泌水孔是一种位于叶的分泌组织，通常在被子植物被发现，由孔洞在表皮或叶边缘分泌水分，经常位于齿状或锯齿状边缘的尖端。泌水孔出现在沉水性水生植物(如:Ranunculus fluitans)与在干旱栖地的草本植物(如:圆叶风铃草 )。他们以维管束鞘与植物维管束系统链接，泌水孔通常在大薸、凤眼蓝、玫瑰、胶冷杉中被观察到。

泌水孔由一群具有充满水的大型胞外空间的活细胞组成，但没有或只有少量叶绿体，代表特化鞘体末端。这些细胞(称为披覆组织细胞)向外开口进入一个或多个表皮下腔室。他们轮流透过开水气孔(open water stoma)与开孔(open pore)与外界沟通。水气孔在结构上与正常气孔相似，但通常较大且失去运动的能力。

A hydathode is a type of secretory tissue in leaves, commonly found in Angiosperms, that secretes water through pores in the epidermis or leaf margin, typically at the tip of a marginal tooth or serration. Hydathodes occur in the leaves of submerged aquatic plants such as Ranunculus fluitans as well as herbaceous plants of drier habitats such as Campanula rotundifolia. They are connected to the plant vascular system by a vascular bundle. Hydathodes are commonly seen in water lettuce, water hyacinth, rose, balsam, and many other species.