The Cyperaceae in Madagascar show increased species richness in upland forest and wetland habitats

Background and aims – Madagascar is a biodiversity hotspot with a high level of plant endemism. However, not all lineages of plants are equally represented and the highest diversity occurs in forest lineages. Cyperaceae frequently occur in grasslands and wetlands in Africa, and the tribe Hypolytreae and Carex subgenus Vigneastra are among the few predominantly forest lineages. We study the Cyperaceae of Madagascar to discover what lineages are represented (genera/tribes), to determine their unique habitats and key functional traits and to investigate patterns of species richness. Methods – The World Checklist of Monocotyledons was queried for Cyperaceae occurring in Madagascar. The global distribution of these species was investigated to identify endemic taxa and to evaluate other botanical countries where widespread species occur. Data on life form, habitat and photosynthetic type were scored from literature and personal observations. Key results – Madagascar has 321 species of Cyperaceae in 33 genera, representing all major clades of the family. The predominantly tropical Cypereae clade composes about half of the sedge flora, of which Cyperus represents about a third of the species in Madagascar. The Cariceae, a predominantly northern hemisphere temperate clade, is unusually highly represented and composes 10% of the sedge flora, occurring mostly in the highlands. In Madagascar, 55 species (17% of flora, mainly Carex and Cyperus) occur in forests and all are C 3 perennials. Bulbostylis and Pycreus, exclusively C 4 taxa with high proportion of annuals compared to C 3 genera in Madagascar, occur outside forests in seasonal or permanent wetlands. Endemism among the sedge flora is 37% (121 species), a third of which (42 species) occur in forests, mostly in the Central and Eastern highlands. Conclusion – Cyperaceae are among top ten species richest angiosperm families in Madagascar. When compared with other botanical countries, Madagascar has the second highest endemism level, second to the Cape Provinces. The sedge flora assembly has involved long distance dispersal(s) coupled with Neogene radiation in upland humid forests and open wetland habitats