Dr. Matt Opel co-authored a publication with A.J. Young, L. Pulido Suarez, & M. Kapralov entitled”Leaf epidermal structure in the dwarf succulent genus Conophytum N.E. Br. (Aizoaceae). The summary reads: The epidermal structure of 66 species and subspecies of the dwarf succulent genus Conophytum N.E. Br. was examined using scanning electron microscopy. Taxa within this genus possess a number of adaptations to their arid environment including sunken stomata, a prominent wax layer and trichomes. The range of epidermal morphologies present in this genus is described and the use of these to inform infrageneric classification in Conophytum is discussed. In many cases the epidermis of closely related species is similar but this is not always the case across the 16 sections that comprise the genus. Whilst this study confirms the assignment of several recently described taxa to existing sections it suggests that the infrageneric classification of Conophytum needs to be re-evaluated.

Young, A. J., L. Pulido Suarez, M. Kapralov, and M. R. Opel. 2017. Leaf epidermal structure in the dwarf succulent genus Conophytum NE Br.(Aizoaceae). Bradleya 35: 217–237. pdf