We propose in this paper to use three regions of plastid DNA as a standard protocol for barcoding all land plants. We review the other markers that have been proposed and discuss their advantages and disadvantages. The low levels of variation in plastid DNA make three regions necessary; there are no plastid regions, coding or non-coding, that evolve as rapidly as mitochondrial DNA generally does in animals. We outline two, three-region options, (1) rpoC1, rpoB and matK or (2) rpoC1, matK andpsbA-trnH as viable markers for land plant barcoding.
