Here's why:

* Ground tissue system is one of the three main tissue systems in plants, along with vascular tissue and dermal tissue.

* Cortex lies between the epidermis (dermal tissue) and the vascular tissue (vascular bundles) in the stem and root.

* Ground tissue is responsible for functions like photosynthesis, storage, and support, which are all roles the cortex plays.

Common cell types found in the cortex:

* Parenchyma cells: These are the most common cells in the cortex. They are involved in storage, photosynthesis, and other metabolic activities.

* Collenchyma cells: These provide flexible support, especially in young stems.

* Sclerenchyma cells: These provide rigid support, often found in older stems and roots.

Important note: The exact composition of the cortex can vary depending on the plant species and the part of the plant being considered.