Plants can have two types of cell walls, primary and secondary. Primary cell walls contain cellulose consisting of hydrogen-bonded chains of thousands of glucose molecules, (Containing β-1,4-linkages) in addition to hemicellulose and other materials all woven into a network. Certain types of cells, such as those in vascular tissues, develop secondary walls inside the primary wall after the cell has stopped growing. These cell-wall structures also contain lignin, which provides rigidity and resistance to compression. The area formed by two adjacent plant cells, the middle lamella, typically is enriched with pectin. Figure adapted from L. Taiz and E. Zeiger, Plant Physiology (1991).
[Some images taken from "Genomics:GTL Transforming Cellulosic Biomass," U.S. Department of Energy Office of Science and Office of Energy Efficiency and Renewable Energy, June 2006, genomicscience.energy.gov/biofuels/ and U.S. DOE. 2006. "Breaking the Biological Barriers to Cellulosic Ethanol: A Joint Research Agenda," DOE/SC/EE-0095, U.S. Department of Energy Office of Science and Office of Energy Efficiency and Renewable Energy, genomicscience.energy.gov/biofuels/.]
Credit or Source: Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science. science.energy.gov/ber/
US DOE. May 2007. Biofuels Primer Placemat: From Biomass to Cellulosic Ethanol and Understanding Biomass: Plant Cell Walls, US Department of Energy Office of Science. (website)