The phenomenon of water rising in plants against gravity is called capillary action. This process occurs primarily in small tubes or spaces within plant tissues, such as xylem vessels. Capillary action is driven by the cohesive forces of water molecules and adhesive forces between water and the plant's cell walls. As water evaporates from the leaves (transpiration), it creates a negative pressure that pulls water upward from the roots. This mechanism is essential for maintaining hydration and transporting nutrients throughout the plant.