A generalized conceptual model of oscillatory transpiration in a cotton plant growing in a nutrient solution under constant environmental conditions is presented. The model is based upon the results and observations of an experimental study and the contemporary literature. It incorporates the values of parameters, of initial and boundary conditions, and of significant variables in the transpiration stream. A non-linear coupling consisting of a hysteresis loop with a time-variant constraint acting between the guard cell potential and stomatal resistance is proposed. Mathematical equations based upon the network variables were solved via a simulation language (CSMP—IBM/360). The model showed gradually damped oscillations early in the light period and sustained oscillations later in the light period. The resulting simulation output agrees satisfactorily with pattern of oscillations observed in vivo. Root resistance changes through the day caused minimal effect on oscillation. The principal causal effect for oscillatory behaviour appeared to be due to stomatal effects.