Field studies in the Gus Engeling Wildlife Management Area, which consists of approximately 4465.5 ha (11,034.1 acres) of the Post Oak Savannah of Anderson County, have resulted in an annotated checklist of the vascular flora corroborating its remarkable species richness. A total of 930 taxa (excluding family names), belonging to 485 genera and 145 families are recorded. Asteraceae (124 species), Poaceae (114 species), Fabaceae (67 species), and Cyperaceae (61 species) represented the largest families. Six Texas endemic taxa occur on the site: Brazoria truncata var. pulcherrima (B. pulcherrima), Hymenopappus carrizoanus, Palafoxia reverchonii, Rhododon ciliatus, Tradescantia humilis, and T. subacaulis. Within Texas, Zigadenus densus is known only from the study area. The area also has a large number of species that are endemic to the West Gulf Coastal Plain and Carrizo Sands phytogeographic distribution patterns. Eleven vegetation alliances occur on the property, with the most notable being sand post oak-bluejack oak, white oak-southern red oak-post oak, and beakrush-pitcher plant alliances.