Annotated Checklist of Texas Endemic Plants (2009)
There is a annotated list of Texas endemic plants on Guy Nesom's website, a draft made by botanist Bill Carr in 2009. It might be a bit dated, but I nonetheless found it interesting to read and it might prove useful to reference in the future.
Carr. W. R. (2009) "No place but Texas: An annotated list of plant taxa endemic to the Lone Star state." The Nature Conservancy of Texas. https://www.guynesom.com/Texendemicsweb.htm.
The list includes everything at the specific level and below.
