The Rotala ramosior post of a few days ago got me thinking. Scott mentioned that it has a C-value of 10 in the Chicago region. In Missouri, it has a C-value of 4. In Indiana it has a C-value of 2. Swink and Wilhelm say, as reiterated by Scott, that it occurs in ditches and areas of recent excavation. Unless ditches and recently excavated sites are pristine, pre-settlement natural community types, I don't see how it could possibly be a 10. Even Running Buffalo Clover, a disturbance dependant species, has a C-value of 3 in Indiana.
Because of this regional bias, I am increasingly convinced that C-values should not be regionally specific. In my opinion, a species’ behavior, as expressed by its fidelity to undisturbed habitat, does not vary from region to region. Rotala ramosior is as weedy in Missouri as it is in the Chicago region and Indiana. Therefore it should have the same C-value regardless of region. Am I missing something? Can anyone give me a reason to believe otherwise?