The botanical exploration of Mexico and Central America has advanced over the past forty years, yet regions like the interior of Chiapas and parts of Tabasco remain underexplored. While Yucatan has been more extensively studied, its xerophytic coastal zone and relict forests require further research. Every significant plant collection continues to reveal new species, necessitating additional material for reevaluation of known species. This volume, supported by the Horace H. Rackham School of Graduate Studies and the Carnegie Institution of Washington, describes fifty-six new species from these areas. Critical specimens were borrowed from major herbaria, and thanks are extended to several botanists for their assistance with these loans.