Systematically diverse assemblages of fossil plants have been collected in late Miocene strata at seven sites in northern Antelope County, Nebraska. Fossils were found in several members of the Valentine and Ash Hollow Formations of late Barstovian to medial Clarendonian (13–10 MYBP) age and unnamed members of the Ash Hollow Formation of late Clarendonian to early Hemphillian (9.5–8.0 MYBP) age. Seeds, fruits, and leaf-sheath fragments of 18 species from the families Equisetaceae, Cyperaceae, Gramineae, Boraginaceae, Juglandaceae, and Ulmaceae are described. These occurrences represent a 200 mile (322 km) eastward extension of the known geographic range of all of the taxa during the Miocene. The occurrence of Juglandaceae is the first reported from widespread Miocene strata of the Ogallala Group in central North America.