Two similar unpublished lists have been generated in the past by other persons or projects. The first, entitled Endemic Vascular Plants of Texas, probably dates from the mid 1970s. It came to the Texas Natural Heritage Program from the files of the long-defunct Rare Plant Study Center at the University of Texas at Austin. Its authorship is unknown, but legend has it that it was the work of a student of Dr. Chester Rowell. Legend has it that this student compiled this first list by painstakingly thumbing through the Manual of the Vascular Plants of Texas (Correll & Johnston, 1970) and writing down every taxon which, in comments about distribution, was described as endemic to Texas.
The second is a list of target species for a project entitled Phytogeographical Investigation of Texas Endemics (Amos, 1991). This list was compiled by Dr. Bonnie Amos of Angelo State University. Dr. Amos's list included those taxa endemic to the political entity of Texas, but also included taxa thought to be endemic to major natural biological regions contained mostly within the state. At this writing (1995), Dr. Amos's work is ongoing, and it promises to outline centers of endemism based on real biological factors rather than artificial political boundaries.
In compiling this current list, the distributions of all of the taxa mentioned in the two preceding lists were reviewed. To date, this review has been limited to published literature and unpublished notes in the files of the Texas Natural Heritage Program. Time has not yet permitted a perusal of herbarium specimens, not even a casual look at the outstanding collection of Mexican material assembled right here in Austin at the University of Texas (LL, TEX). The few amendments to the Texas endemics list that have come to light from published literature will undoubtedly be eclipsed by information gathered quietly during the last twenty years and awaiting rediscovery in various herbaria.
While some well-established taxa once thought to be endemic to Texas have proven to range beyond the state's political boundaries, other endemic taxa have been described since the first list was attempted twenty years ago. In compiling this list, the author has lazily relied upon Dr. Marshall Johnston's most recent "update to the manual" (Johnston, 1990) to call recent taxonomic splitting to his attention.
This is a work in progress. Review of literature published during the last twenty years is admittedly very incomplete, and herbarium research has not even been attempted. County distributions, when provided, are incomplete, as are literature citations and references to availability of illustrations. Treatment of Cactaceae is particularly unfinished; several endemic taxa cacti have probably been temporarily omitted...