Comment on drag and reconfiguration of macrophytes

Summary 1. The experimental approach of Sand‐Jensen (2003) , designed to examine quantitatively the response of freshwater macrophytes to physical forcing by moving water, is discussed. Specifically, it is emphasised that neglecting the principal difference between the wetted and the frontal area of the aquatic plants necessarily provides unacceptably large errors in estimates of drug coefficient. 2. The empirical methodology employed in the study to generalise the data ( Sand‐Jensen, 2003 ) suffers from a dimensional problem and can potentially lead to misleading conclusions. The methodology could be improved by using the relationship between dimensionless values of drag coefficient and dimensionless Reynolds number.