Stems are the main support structures of plants, connecting the roots to the leaves and flowers. They play a crucial role in transporting water and nutrients from the roots to the rest of the plant. Stems can be thick and sturdy, like those of trees, or thin and flexible, like those of grasses. In addition to support and transport, stems also help plants grow taller to reach sunlight. Some stems can even store food, like the potato, which is actually a modified stem. Overall, stems are essential for a plant's survival and growth, making them a vital part of the plant's structure.