A century of progress in grass systematics

Although the c. 10,000 species in the Poaceae places it as the fifth largest flowering plant family, a number of biological features raise it to a unique position. The family has contributed crop species that provide about 80% of the annual global food (FAOSTAT 1999). In fact, four of the top crops that feed the world are cereal crops: wheat, rice, corn, and barley. This economic significance is matched by an ecological dominance as grasses cover about one fifth of the earth (Shantz 1954). Grasslands are signature of the Poaceae. Because of this economic and ecological importance, grasses have attracted considerable attention in the biological and agricultural sciences. The past century showed enormous amounts of research conducted on various biological aspects of the family, including systematics, genetics, cytogenetics, breeding, physiology, anatomy, developmental biology, chemistry, chromosome structure, and, more recently, whole plastid and nuclear genome sequences. Results from these studies have provided a wealth of information on the biology of the family, which have become and remain valuable resources used in furthering our understanding of Poaceae systematics and in assessing the mode and tempo of grass evolution. Development of our views of grass systematics followed major trends in advancement in the sciences and engineering. Major discoveries come in spurts and are usually followed by periods of relative stagnation. Optical development associated with microscopes provided a closer look at various anatomical features; advancement in chemical techniques revealed information on a number of molecules such as flavonoids, proteins and alkaloids; development of computers and various analytical software programs enhanced the capability of handling large data sets and facilitated large-scale analyses of available grass data; and finally, the current advancement in molecular biology and biotechnology provided us with the tools to look at information derived from genes and genomes. Parallel to, or as a consequence of, these major developments, the field of grass systematics underwent a series of refinements that individually or collectively corresponded to the progressive stages cited above. 355 KEW BULLETIN 62: 355–373 (2007)