In Ky. this robust southeastern perennial is largely restricted to southern regions of the state, but it is locally abundant in wetlands there. C. entrerianus Boeckeler (C. luzulae var. e.) is a noxious weed similar to pseudovegetus. In recent decades, it has spread onto the Gulf Coastal Plain from South America (FNA 23, W and cited literature). It has been found in sw. Mo. (SE) and may be expected in far western Ky. C. entrerianus differs in its achenes, which are smaller and less elongated, and its heads do not have the "irregularly lobulate" character of pseudovegetatus (see above sources for keys).