Several studies about inselberg specific bromeliads and orchids (e.g. Barbara et al. 2007, Hmeljevski et al. 2015) have shown that gene flow between geographically isolated populations is relatively low what underlines their character as terrestrial habitat islands. No detailed data are available yet about the population structure of inselberg specific Velloziaceae. Own studies in Brazil and Madagascar have demonstrated, however, that mat-forming Velloziaceae form extensive clonal populations making the delimitation of individuals difficult. We thus assume that populations of Velloziaceae species on individual inselbergs are genetically relatively uniform but are clearly distinct from those on other inselbergs. Based on preliminary observations about V. plicata in Brazil and X. dasylirioides in Madagascar it became clear that certain species show a broad range of morphological plasticity. We expect that mainly within widespread species the isolation of inselbergs throughout Gondwana has contributed to differentiation processes and thus to diversification.