XVI International Botanical Congess

Under the phylogenetic species concept, the minimum condition of specific status is the presence of one or more fixed characters, since only these are capable of reliably inferring the historical genealogical relationships between the taxa bearing them. If species are recognized by ordinary morphological means (usually a practical necessity), then application of the PSC generally will decease the number of species recognized, since many currently recognized species are phenetic entities lacking fixed characters. Since phenetic variation can be pronounced and is often genetically based, the recognition of infrapsecific taxa remains desirable. Following this rationale, a recent monograph of Leptochloa reduced several phenetic species to the rank of subspecies.