Xyris, the yelloweyed grasses, is a genus of flowering plants in the Yellow-eyed-grass family. The genus counts over two hundred fifty species, widespread over much of the world, with the center of distribution in the Guianas. Stand of mostly Xyris complanata in a small wetland The leaves are mostly distichous, linear, flat and thin or round with a conspicuous sheath at the base. They are arranged in a basal aggregation. The small, yellow flowers are dioecious, borne on a spherical or cylindrical spike or head (inflorescence). Each flower grows from the axil of a leathery bract. The fruit is a non-fleshy, dehiscent capsule. In Xyris complanata a single flower bud on the spike appears in the morning, and expands into a conspicuous flower during the afternoon hours.