Explain Protoderm in primary growth in shoot?
The protoderm is one of the so-called "primary tissues" because it is formed first during germination and subsequent bud growth and development. The protoderm produces new cells on the surface of the apical meristem, and these surface cells migrate downward and mature into the epidermis of the shoot and leaves.
The epidermal layer provides physical protection for the other internal tissues, and most importantly, guards against drying out. The epidermis produces an outer waxy coating from a substance known as cutin. This cuticle layer prevents evaporative water loss. However, leaves need carbon dioxide and they need to get rid of oxygen, so they provide openings for this gas exchange through special cells called guard cells. Two guard cells make up a functional unit, whose scientific name is stomata, or stomate.