Purple Nut Sedge
Cyperus rotundus
Bulrush
Scirpus acutus
Grass-like weed of wet soils such as lawns and irrigated agricultural fields in the Sonoran Desert. Occas. in riparian habitats. Photograph is hosted at Wikimedia where there are more photos of sedge species. Detailed Description
Robust pond and marsh plant with tall stems, trangular in cross section. Tip extended into sharp point. Detailed Description
Umbrella Plant
Cyperus involucratus
The inflorescence is subtended by a radial array of slightly ascending bracts forming an inverted cone. Detailed Description