What is the main function of phellem, commonly known as cork?

Phellem, or cork, serves primarily as a protective layer for plants. Its structure is composed of a suberized cell wall that makes it highly impermeable to water and gases, which provides several benefits. The key function of cork includes protecting the underlying tissues from desiccation, preventing water loss and thereby helping the plant retain moisture. Additionally, it acts as a barrier against pathogens, injury, and physical damage.

While photosynthesis involves chlorophyll-rich tissues that are not found in cork, and water absorption is primarily facilitated by roots and other specialized tissues, cork does not store nutrients in the way that specialized tissues like parenchyma do. Thus, its main role in the plant is accurately described as protection against desiccation and injury.