exocarp

Exocarp, also referred to as epicarp in some botanical texts, is the outermost layer of a fruit’s pericarp. It develops from the outer wall of the ovary and forms the fruit’s skin or rind. The exocarp is typically composed of epidermal tissue with a cuticle and protective waxy coatings, contributing to rigidity and reducing water loss. The color and texture of the exocarp vary widely among species and are often due to pigments such as carotenoids or, in some fruits, anthocyanins.

The pericarp is conventionally divided into three layers: exocarp (outer), mesocarp (middle), and endocarp (inner). The exocarp may be very thin or thick and, in some fruits, it forms a distinct rind; in others it blends with the mesocarp. In citrus, the outer rind is sometimes described as the flavedo (the colored exocarp) with the white albedo as part of the mesocarp. In many fleshy fruits, the exocarp is the part that is eaten as the skin.

Functions include protection of the developing ovule, moisture retention, and defense against herbivores and pathogens. It also can bear pigments and oils that contribute to the aroma and appearance of the fruit.

In summary, the exocarp is the protective, outermost layer of the fruit, forming the visible skin that interfaces with the external environment.