What causes marcescence?
The reasons for marcescence are not clear, but theories abound. The presence of dead leaves might protect leaf buds during the harsh, dry conditions of winter. Marcescent trees may also benefit from the shed leaves that arrive and decompose in the spring, just when they’re needed for new roots and leaves. The evolutionary reasons for marcescence are not clear, theories include: protection of leaf buds from winter desiccation, and as a delayed source of nutrients or moisture-conserving mulch when the leaves finally fall and decompose in spring.