A plant’s stem serves as the support structure for its above ground components and as a conduit through which water and nutrients can travel. When a stem is green due to the presence of chlorophyll, it also produces food. In some plant species, the stem stores energy or food for future use.
The stems of plants vary widely, depending on the lifestyle, growth habit and location of the plant. For example, sunflowers have long, thick stems that lift the flower heads up to 6 feet in the air. By contrast, the stems of some vines are long, flexible and feature extensions called tendrils that help them ascend trees. Some stems, such as stolons, lie horizontally, and this occurs when a plant undergoes vegetative propagation, which is a method of asexual reproduction.
Humans and other animals rely on the stems of plants as well. Humans use stems as food, a source of fibers for textiles and as a fuel for fires. Many plants have thorns, which are modified stems that provide nutrients and protect from herbivores. Humans use the stems of some plants, such as celery stalks and broccoli, as food. Animals also consume stems as food, and some species use the hollow interiors of plant stems as a habitat.