What produces protective cork cells after a stem outgrows its original epidermis?

The production of protective cork cells after a stem outgrows its original epidermis is primarily the function of the cork cambium. The cork cambium is a lateral meristem that generates cork tissues, which serve as a protective barrier for the plant, helping to maintain water loss and protect against pests and diseases. As the stem grows, the original epidermis can become damaged or insufficient, leading to the need for new protective layers.

Cork cells created by the cork cambium are part of the periderm, which replaces the epidermis in mature plant stems and roots. This process is essential for the adaptability and survival of the plant as it increases in size.

Other options, such as the apical meristem, are involved in the growth of the plant but specifically contribute to lengthening the stem and creating leaf buds. Dormant buds are areas of the plant that can produce new growth but do not contribute to the protective function. The pith, located in the center of the stem, primarily serves as storage and does not produce protective cells. This context illustrates why the cork cambium is the correct answer for producing protective cork cells during stem growth.