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How does the protoderm develop into the plant epidermis?

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fern life cycle — plant development The life cycle of the fern. (1) Clusters (sori) of sporangia (spore cases) grow on the undersurface of mature fern leaves. (2) Released from its spore case, the haploid spore is carried to the ground, where it germinates into a tiny, usually heart-shaped, gametophyte (gamete-producing structure), anchored to the ground by rhizoids (rootlike projections). (3) Under moist conditions, mature sperm are released from the antheridia and swim to the egg-producing archegonia that have formed on the gametophyte's lower surface. (4) When fertilization occurs, a zygote forms and develops into an embryo within the archegonium. (5) The embryo eventually grows larger than the gametophyte and becomes a sporophyte.

In plant development, the protoderm is one of three primary meristems that form in concentric regions immediately behind the apical meristem. As the plant grows, these undifferentiated cells undergo a process of differentiation—a change in structure and physiology—to become the epidermis, which serves as the outermost protective layer of the primary plant body.12

Once differentiated, the epidermis functions as a complex tissue system that regulates the exchange of gases and water vapor through specialized structures like stomata and guard cells. Additionally, epidermal cells can undergo further divisions to produce trichomes, which provide protection against herbivores, reduce water loss, or assist in nutrient absorption. Because the protoderm is a primary meristem, the resulting epidermis is considered a primary tissue, distinct from the secondary protective tissues, such as the periderm, that arise from lateral meristems like the cork cambium during secondary growth.32