Meristic characters proposed by Fernald (1945) to separate Ruellia humilis Nutt. from R. caroliniensis (Walt.) Steud. were shown by Long (1961) to break down under analysis without reference to sympatry and without evidence of cross-breeding. Essentially, these characters are: In R. humilis, leaves are mostly uniform, sessile or subsessile, stems much branched, often depressed-ascending, nodes many, subequal, several floriferous. In R. caroliniensis, upper leaves are markedly larger than lower (excepting terminal growth), plants remotely branched to simple, erect, with few nodes, the upper much shorter than the lower, and only the uppermost floriferous. While Ruellia students can generally recognize these species through familiarity, key characters generally offered by current manuals sometimes prove disconcerting in non-conforming specimens.