Stomata are the key nodes linking photosynthesis and transpiration. By regulating the opening degree of stomata, plants successively achieve the balance between water loss and carbon dioxide acquisition. The dynamic behavior of stomata is an important cornerstone of plant adaptability. Though there have been miscellaneous experimental results on stomata and their constituent cells, the guard cells and the subsidiary cells, current theory of stomata regulation is far from clear and unified. In this work, we develop an integrated model to describe the stomatal dynamics of seed plants based on existing experimental results. The model includes three parts: 1) a passive mechanical model of the stomatal aperture as a bivariate function of the guard-cell and the subsidiary-cell turgor pressures; 2) an active regulation model with a targeted ion-content in guard cells as a function of their water potential; and 3) a dynamical model for the movement of potassium ions and water content. Our model has been used to reproduce different experimental phenomena semi and stomatal responses to environment conditions.