The periderm is the protective outer tissue of woody roots and stems, replacing the delicate epidermis as plants undergo secondary growth. Composed of cork (phellem), cork cambium, and phelloderm, it forms the bark that shields the plant from water loss, pathogens, and physical damage. In food plants, the periderm is the familiar skin of potatoes, carrots, and other root vegetables: the corky layer that must be intact for good storage, since wounds invite rot, and whose damage triggers wound-healing that consumers see as skinning or scuffing. Cork itself, harvested from the periderm of cork oaks, seals wine bottles. For the cook, the periderm is simply peel, removed or scrubbed according to recipe, though much of a root vegetable’s fibre and phytochemicals concentrate in and just beneath it.