The outer layer of a branch of a tree typically undergoes changes as the plant ages, forming cork tissue to provide additional protection. In contrast, the outer layer of a young stem may consist of primary meristem and epidermal tissue.
How does the outer layer of a branch of a tree differ from the outer layer of a young stem?
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The outer layer of a tree branch, commonly known as the bark, is generally thicker and more complex than the outer layer of a young stem. Bark includes multiple tissue layers, such as the protective outer cork layer, secondary phloem for nutrient transport, and often layers of old, dead tissues. In contrast, the outer layer of a young stem, often referred to as the epidermis, is simpler and primarily consists of a single layer of cells. The epidermis provides protection and regulates gas exchange, but it lacks the complexity and diverse tissues found in the more mature bark of a tree branch.
The outer layer of a branch in a tree typically consists of cork tissue, formed by the activity of cork cambium, providing protection. In contrast, the outer layer of a young stem comprises living epidermal cells involved in growth and photosynthesis. Cork tissue is dead and lacks intercellular spaces, while epidermal cells are living and may contain chloroplasts. Cork tissue is thick, rough, and impermeable, serving as a barrier against physical damage and water loss, while the epidermis of a young stem is thinner, smoother, and flexible, supporting growth and photosynthesis.