ABSTRACT.  About 42% of the weedy sedges (Cyperaceae) are in the genus Cyperus.  An additional 43% are in Eleocharis, Fimbristylis, Isolepis, Schenoplectus, and Scirpus, while the remaining 15% are in Bulbostylis, Carex, Fuirena, Kyllinga, Rhynchospora, Scleria, and other genera.  Purple nutsedge (Cyperus rotundus L.) is considered the world’s worst weed infesting more than 52 crops in about 100 countries.  It is also troublesome in urban areas and natural plant communities following soil disturbance.  Yellow nutsedge (Cyperus esculentus L.), smallflower umbrellasedge (Cyperus difformis L.), and rice flatsedge (Cyperus iria L.) rank 16, 32 and 33 among the world’s worst agricultural weeds, respectively.  Sedges possess diverse ecological, biological, and reproductive traits and are able to survive a wide range of environmental conditions.  The most troublesome sedge weeds germinate, grow, reproduce, and disperse rapidly; maintain large reservoirs of seed, tubers, and/or rhizomes in the soil; and resist chemical, cultural, and mechanical control methods.