Taxonomic Confusion Permits the Unchecked Invasion of Vernal Pools in California by Low Mannagrass (Glyceria declinata)

Abstract

AbstractChloroplast DNA sequences and recently established morphological characters were used to confirm the widespread invasion of California's vernal pools by European low mannagrass. Morphological similarities between low mannagrass and western mannagrass have led to different taxonomic treatments, depending on the geographical extent of a particular flora. When California's flora was last revised, the two species were combined as western mannagrass, which was then considered to be a native species. Unfortunately, the revised flora was published just as low mannagrass began to rapidly expand its range within the state and, because it was considered to be a native species in the new flora, no actions were initiated to limit the invasion. Our data show that low mannagrass was present at all localities in the Central Valley of California that were investigated, indicating a widespread and undetected invasion. The invasion has led to a degradation of the vernal pool ecosystems, which are the habitat of many federal and state protected endangered and threatened species.