The Cenchrus spinifex group (Poaceae: Panicoideae) in Texas and notes on reinstated Cenchrus S.S. in the United States

An account of the Cenchrus spinifex group for Texas is provided based on an examination of the type specimens, field work, and the examination of herbarium accessions and digital images. From this study several species previously synonymized under Cenchrus spinifex are reinstated: C. albertsonii, C. incertus, C. roseus, C. strictus (coastal S. Carolina to Florida), and C. bambusoides (Florida, coastal southern Mexico). The Mexican species Cenchrus roseus is reported new for Texas. A new species of Cenchrus from Texas is described: C. densiflorus Wipff, sp. nov. from southern Texas. Keys to the documented taxa in Texas and the United States, descriptions, images of the types for each taxa, and distribution maps are provided.