Abstract Accurate measurement of the hydroperiod in isolated wetlands currently relies upon the installation and frequent monitoring of devices such as piezometers and staff gauges. Observations of biological indicators of the hydroperiod may be able to supplement data collected from these devices and could potentially replace them as a means of accurately determining this hydrologic interval. The study objective was to determine whether adventitious root formation and maturation on buttonbush (Cephalanthus occidentalis) could be used as a viable indicator of the hydroperiod in isolated wetlands. Buttonbush seedlings were flooded in a controlled environment over a three month period in the summer of 2011. During this time, the length and complexity of adventitious roots observed were recorded. When average lengths of primary roots were regressed against time of inundation, a linear regression (r2) of 0.94 was calculated. The structure of these roots was then compared to adventitious roots observed in a natural wetland with a hydroperiod of 12 months. This was undertaken to allow a comparison of the observed lengths and complexity of adventitious roots in the controlled experiment with roots in the natural environment. The regression of both sets of observations yielded an r2 value of 0.99. Consequently, the results of this study found that the length of adventitious roots on buttonbush can help determine the hydroperiods of isolated wetland systems.