In Texas, about 5400 species are currently known to grow outside of cultivation, a 12% increase from the 4839 species accounted for in the Manual of the Vascular Plants of Texas (Correll & Johnston 1970).
The increase has resulted from continued field exploration of the state as well as from herbarium-based studies that refine species definitions and identifications. Many non-native species are migrating into the state, but many "new" native species have been here all along, though often represented by few individuals in restricted localities. Native and non-native species present different challenges for conservation, and it is significant to track both categories.
