Xyridaceae – the Yellow-eyed grass family

by Lisa M. Campbell

These pages are being developed to present information on the evolutionary history, nomenclature, biogeography, natural history, distribution, and phenology of Xyridaceae. A list of herbarium specimens will also be provided.

Introduction—Xyridaceae (five genera/415 species) are a monophyletic, morphologically diverse group of petaloid monocots included in the order Poales. Species occur in oligotrophic, seasonally or permanently wet habitats, such as savannas, heath- and pinelands, low- and highland scrub, or sandstone or granitic outcrops. The geographic distribution of Xyridaceae is tropical to subtropical (in the Americas, Africa including Madagascar, southeast Asia, and Australia), with a small number of species occupying ecologically similar habitats in adjacent temperate areas. Almost 95 percent of the species are included in the genus Xyris Gronov. ex L. Xyris is most species-rich in the Neotropics, with centers of diversity on the Brazilian Shield (160 spp., 103 endemic) and the Guiana Shield (90 spp., 69 endemic). Other areas of diversity are tropical Africa (78 spp., 77 endemic), eastern U.S.A. (26 spp./17 endemic), and Australia (25 spp., 21 endemic). Four other genera are endemic to northern South America (extending to 23° S): Abolboda (23 spp.), Achlyphila (one sp.), Aratitiyopea (one sp.), and Orectanthe (two spp.). Many of the species in these four genera are endemic to the Guiana Shield, especially the isolated table-top mountains (tepuis) of the Precambrian marine sandstone Roraima Formation.


Example Species Page

Species descriptions and living plant images will be made available over the course of the project.