Velloziaceae on inselbergs
On tropical inselbergs a typical set of habitat types and plant communities occurs (Porembski 2007). Very common on open slopes are mats formed by monocotyledons. The carpet-like monocot-mats are literally glued to the underlying rock. Dominant mat-formers on both neotropical and paleotropical inselbergs are desiccation-tolerant, partly shrubby species of Cyperaceae (e.g. Afrotrilepis), Poaceae (e.g. Tripogon) and Velloziaceae (e.g. Vellozia, Xerophyta). It can be estimated that in total c. 300 desiccation-tolerant vascular plant species occur on tropical inselbergs. Amongst these so-called “resurrection plants”, Velloziaceae form the largest family. Most Velloziaceae prefer open rocky slopes of various degrees of inclination where they form mats of different sizes. All species of Velloziaceae that grow on inselbergs are desiccation-tolerant and are able to survive several weeks or months in a desiccated state. Brazilian inselbergs are mainly characterized by species of Vellozia as mat-formers whereas in Africa and Madagascar Xerophyta species occur. Both genera are notorious for difficulties in the delimitation of taxonomic units.