Plant macromolecular systematics in the past 50 years: one view

An overview of plant macromolecular systematics during the period 1950-2000 is presented. The general Vend during this period has been from secondary compounds (not included in this review) to proteins and then to DNA. Amino acid sequencing of proteins from the 1960s through the 1970s, while having very little lasting impact on plant phylogeny, raised a number of issues that continue to be discussed. Enzyme electrophoresis has provided data at the population and lowest taxonomic levels, and has stimulated discussions and studies on the tempo and mode of speciation. DNA data, initially from restriction sites and subsequently from sequencing, have been employed extensively in generating phylogenies for groups ranging from species and genera up to plants as a whole. Despite the potential, molecular data have been used infrequently to study evolutionary processes and speciation. Phylogenies generated from molecular data provide the necessary framework for such investigations. The incorporation of molecular data has had a positive stimulatory effect on plant systematics during the past five decades, but the results of molecular studies are of greatest value when they are part of more broadly-based investigations that include more traditional approaches such as field and chromosomal studies. However, one of the side effects of increased emphasis on molecular systematics has been less emphasis on traditional systematic studies. Hopefully, the next five decades will witness a melding of the old and new to continue the unending synthesis that makes systematics such a vital discipline in plant biology.