Phelloderm is a layer of cells found in the bark of woody plants, specifically beneath the cork cambium. It is part of the plant's secondary growth and plays a role in protecting the inner tissues from damage and pathogens. The phelloderm consists of living cells that can contribute to the storage of nutrients and water. Unlike the outer layer of bark, which is primarily made up of dead cells, the phelloderm helps maintain the health of the plant by providing a barrier and supporting the overall structure of the bark.