This botanical study meticulously documents the plant species and ecological communities found within the Lawther - Deer Park Prairie Preserve in Texas. Through field surveys conducted over several years, the researchers compiled an annotated checklist of 407 vascular plant species, noting both native and non-native occurrences. The report identifies six distinct plant community associations based on dominant vegetation, landscape features, and soil conditions. Comparisons with other coastal prairies in Texas reveal that while Deer Park Prairie has a higher percentage of non-native species, it exhibits remarkable species richness despite its smaller size, highlighting its conservation significance. The findings underscore the importance of preserving these rare coastal prairie ecosystems and continuing floristic research.