In 1958, a single volume in the original series of this Encyclopedia adequately summarized the state of knowledge about plant carbohydrates. Expansion into two volumes in the New Series highlights the explosive increase in information and the heightened interest that attended this class of compounds in the interven­ ing years. Even now the search has just begun. Much remains to be accom­ plished; e.g., a full description of the plant cell wall in chemical terms. Why this growing fascination with plant carbohydrates? Clearly, much credit goes to those who pioneered the complex chemistry of polyhydroxylated compounds and to those who later sorted out the biochemical features of these molecules. But there is a second aspect, the role of carbohydrates in such biological func­ tions as host-parasite and pollen-pistil interactions, the mating reaction in fungi, symbiosis, and secretion to name a few. Here is ample reason for anyone concerned with the plant sciences to turn aside for a moment and consider how carbohydrates, so many years neglected in favor of the study of proteins and nucleic acids, contribute to the physiological processes of growth and devel­ opment in plants.