Cellulose and the Evolution of Plant Life

Abstract

he biosphere is dominated by land-plant biomass. An estimated, 99.9% of the 'lobal standing crop, the total quantity of biomass present in the biosphere, is classified as vegetation (Lieth and Whittaker 1975). Primary production, the yearly contribution of plant life to the standing crop, represents 97.7% of the total annual global production. Although marine plant life (including phytoplankton) makes up 32% of the total annual primary production, it represents only 0.2% of the global standing crop (Woodwell et al. 1978). Therefore, terrestrial vegetation constitutes almost all of the biomass on earth. Plant biomass is primarily comprised of cell wall materials, which therefore represent the vast majority of the dry weight of living tissues (Figure la). Between 40% and 60% of the total mass of the cell wall is comprised of cellulose, a polymer of 100-15,000 units of P-1,4 glucose (Figure Ib) (Cote 1977, Delmer 1987, Stamm 1964), depending on the plant tissue and species. The remainder of the cell wall includes hemicelluloses, lignin polymers, and pectic substances deposited differentially in the several cell wall layers (Cote 1977,