"The Bahía Magdalena region of the Baja California Peninsula is floristically part of the southern Sonoran Desert. It has several particular geographical features, of particular importance the influence of the cold California Current. We present a floristic study of the higher plants on a land area covering 5,158 km2. The flora has 506 taxa: five ferns, two gymnosperms, 438 magnoliopsida (dicotyledons), and 60 liliopsida (monocotyledons), representing 85 families and 280 genera. The plant families with major species diversity are: Asteraceae, Poaceae, Euphorbiaceae, and Fabaceae. The flora was categorized into nine life forms: perennial herbs (127) and annuals (143) represent 54 % of all species. The flora occupies eight plant communities, which are described; the most extensive community is the fog sarcocaulescent scrubland. From a biological perspective, Margarita and Magdalena islands are important areas to preserve as core zones in a future management plan because they support 19 endemic species. Mangroves and sea grass marshes are important areas serving as nursery habitats for marine fauna. Mexican environmental authorities are considering establishing a reserve to protect biodiversity in the region."