The genus Opuntia Miller is one of the most misunderstood and ignored genera of plants occurring in the southeastern United States. This study focused on the clarification of Opuntia stricta (Haw.) Haw., Opuntia macrarthra Gibbes, Opuntia pusilla (Haw.), Opuntia dillenii (Ker Gawl.) Haw. and Opuntia tunoidea Gibbes on the coast of South Carolina. A comprehensive literature review was completed to gather an understanding of Opuntia biology, species concepts and geographic range. The objectives of the morphological study were to determine if Opuntia taxa matching past descriptions of the five species chosen were present, what the morphological characteristics of the individuals collected were, if each could be differentiated into five morphologically distinct groups separate from Opuntia lindheimeri (Engelm.), Opuntia lata (Small) and Opuntia mesacantha (Raf.) ssp. mesacantha (Majure), and if eight species analyzed behaved on the level of a morphological species. The results from the statistical analysis revealed that there appears to be five morphologically distinct species on the coast of South Carolina that are different from Opuntia lindheimeri. Due to limited habitat O. dillenii had to be excluded from the ecological study. The objectives of the ecological and geographic range study were to get a better understanding of Opuntia presence of the coast of South Carolina. This involved analyzing ecological variables collected using the protocol developed by the Carolina Vegetation Survey. Correlation graphs revealed sites indicative of Opuntia in general. Partition analysis was used to build path maps of variables that have a direct impact on the cover value of Opuntia. When interpreted the path maps indicate that four of the chosen study species occupy a weak adaptive zone ecologically. As an addition to ecological study, distribution maps were constructed. They show the location of Opuntia species at the time of the study
