A well-preserved Paleocene flora of 39 species from the Fort Union Formation near Baggs, Carbon County, Wyoming has been studied. This is the first study of the plant megafossils in this area. The most abundant species collected are: Carya antiquorum Platanus nobilis, Cercidiphyllum arcticum and Platanus raynoldsi. Together they represent 74% of the flora. The flora has been dated as Upper Middle Torrejonian. This report is also the first paleoecological study of any North American Paleocene flora. Two methods were used to determine the paleoclimatic conditions of the flora. The first was an analysis of leaf margin characteristics, comparing them to characteristics of modem floras. The second method was an analysis of leaf size comparing the average leaf length and leaf size profile to that of modern floras. Both of these studies suggest that this flora lived in a warm-temperate to subtropical, seasonably dry to moist climate. A correlation of the identified species to their nearest living relatives and their favored climates supports this conclusion.