The rocky outcrops are indeed islands amidst a “sea” of soil and thus their floristic composition and species diversity are influenced by stochasticity. Our discovery was settled to regional level, mainly from the Mantel tests (rM = 0.41, p = 0.01) and partial Mantel (rM = 0.41, p = 0.03), significant when contrasting the floristic x geographical distances and floristic x geographical distances with environment distance weighted, respectively. At the local level, clustering by Group mean (UPGMA) did not show a general pattern for the geographical distance, suggesting that in outcrops stochastic processes are the major actors at the regional scale while the local level need to be more intensely studied in order to reach better conclusions.