The Leaf has evolved to:

The root system usually grows below ground

Plant organs are composed of three tissue systems:

Vascular Tissue Dermal TissueGround Tissue

The vascular tissue distributes water and solutes through the plant body

The dermal tissue system covers and protects the plants surfaces

The epidermis covers the primary plant body

The periderm replaces the epidermis when roots and stems increase in diameter and

become woody