Plant cell walls are typically considered as complex structural matrices that surround all plant cells. They consist mostly of polysaccharides, but also contain components such as lignin, structural lipids and proteins in specialized cell types.

Plant cell wall model

However, the term "plant cell wall" is also used more broadly to refer to the entire compartment outside the plasma membrane that forms a continuum throughout the plant, also termed the "apoplast", or apoplastic compartment.

Green fluorescent protein that has diffused throughout the cell wall and apoplastic compartment surrounding an onion epidermal cell. Scale bar represents 50 micrometers.