A botanical macroscope.

I n 2003 zoologists proposed a short, standardized DNA sequence from a uniform locality on the genome to serve as a DNA barcode to identify the species of tissue from almost all animals—reliably, quickly, and economically. In 2008 two New York City high school students, Kate Stoeckle and Louisa Strauss (1), used the accumulating barcode reference library to prove that about 1⁄4 of fish items they purchased in Manhattan were inaccurately labeled. Their ‘‘Sushigate’’ investigation earned front page coverage in the New York Times and attention from top managers at major food retailers and caterers. Equal curiosity would surely attach to revelations of the contents of jars of plant powders that herbalists sell. Or to seedlings in a garden, a regrowing forest, or an exotic jungle. ‘‘A DNA barcode for land plants,’’ by the Plant Working Group of the Consortium for the Barcode of Life (CBOL) in this issue of PNAS (2) hastens the prospect that many more people can speedily obtain good identifications. To extend barcoding to plants, 52 authors from 24 institutions in 9 nations, led by Peter Hollingsworth of the Royal Botanical Garden in Edinburgh, propose a pair of short sequences totaling about 1,450 base pairs from rbcL and matK as the foundation for a DNA barcode library for plants. Using rbcL matK in the sample of 907 specimens examined, the Plant Working Group discriminated species in 72% of cases, with the remaining species being matched to groups of congeneric species with complete success. The U.S. Food and Drug Administration and many other organizations around the world concerned with commerce in plants should take notice. Barcoding will ease their job to protect consumers, and justify a large societal investment in building a global reference library for plants as well as animals and fungi. Meanwhile, entrepreneurs are likely to make handy tools available not only for sushi eaters but for the millions of people who worry about food allergies and the tight group of investigators who worry about trade in endangered woods. DNA forensics for nature are a practical boon. The ability of a consortium to field a team promptly for an orderly examination of a new technique speaks volumes. Bravo. Instead of haphazard scouting, the Plant Working Group, building on a prior search cultivated by Robyn Cowan of the Royal Botanical Garden (Kew), marshaled knowledge of a wide geographic range without delay. They applied the crucial criteria of