The cell wall in plants is triple layered. The sequence of cell wall layers from outside to inside is
 

primary cell wall$\to$ secondary cell wall$\to$ middle lamella
 

primary cell wall$\to$ middle lamella $\to$secondary cell  wall

secondary cell wall $\to$ primary cell wall$\to$ middle  lamella

middle lamella$\to$ primary cell wall$\to$ secondary cell  wall