Apoplast vs. Symplast — What's the Difference?

Inside a plant, the apoplast is the space outside the plasma membrane within which material can diffuse freely. It is interrupted by the Casparian strip in roots, by air spaces between plant cells and by the plant cuticle.

The symplast of a plant is the inner side of the plasma membrane in which water and low-molecular-weight solutes can freely diffuse. Symplast cells have more than one nucleus.

(botany) The space outside of a plant's plasma membrane through which water and soluble nutrients are transported across a tissue or organ

(biology) The inner side of the plasma membrane of a plant in which water can freely diffuse.