Secondary cell wall

The secondary cell wall is a structure in found in many plant cells, located between the primary cell wall and the plasma membrane. The cell starts producing the secondary cell wall only after the primary cell wall is complete and the cell has stopped growing.

The secondary cell wall consists mainly of cellulose, but also other polysaccharides, lignin, and proteins. It sometimes consists of three distinct layers - S1, S2 and S3 - where the direction of the cellulose differs between the layers.

Wood consists mostly of secondary cell wall, and holds the plant up against gravity.

Some secondary cell walls store nutrient, such as those in the cotyledons and the endosperm. These contain little cellulose, and mostly other polysaccharides.