Orchidaceae of the Grumari restinga: floristic and similarity among restingas in Rio de Janeiro state, Brazil

Orchidaceae is one of the largest and most diverse plant families in the world. The number of floristic studies of this family in Rio de Janeiro state, Brazil, has increased significantly in recent years. However, only a few such studies have been conducted in areas of restinga vegetation and none of those have examined the similarity, in terms of orchid diversity, among such areas. The present study sought to improve our knowledge of the Orchidaceae diversity occurring in Grumari restinga, as well to compare the diversity of orchids among Grumari and other restinga areas using cluster analysis. We found 15 genera and 19 species. Cluster analysis demonstrated that restingas located on islands are considerably different from those on the mainland, and no relationship was observed between floristic similarity and geographical proximity. As such, the present study shows that each area of restinga hosts different Orchidaceae species, demonstrating the importance of preserving this threatened ecosystem and this plant group