Plant Species List Lower Rio Grande Valley and Santa Ana National Wildlife Refuges Update: September 12, 1997 This table contains all plant species that have been reported on tracts of Lower Rio Grande Valley NWR, or on other conservation lands in the Area of Ecological Concern. A total of 776 entries are included in the table; approximately 1,200 are believed to occur in the Area of Ecological Concern. Some species have not been independantly verified. Furthermore, in cases where more than one valid taxonomic treatment exists, all synonyms are included. This is especially true in the Cactaceae, due to the taxonomic problems in that family. This table includes 31 entries in Cactaceae, which represent only 23 taxa.