Here's why:
* Lack of vascular tissue: Nonvascular plants, like mosses and liverworts, don't have specialized vascular tissue (xylem and phloem) for transporting water and nutrients. This means they rely on other mechanisms for support.
* Cell wall structure: The cell walls of nonvascular plants are composed of cellulose and other complex carbohydrates, providing rigidity and structural support. This allows them to maintain their upright form.
* Water absorption: Nonvascular plants absorb water directly from their surroundings, and their cell walls help retain this moisture. This turgor pressure, created by water filling the cells, further contributes to their structural support.
While they may not have a rigid, woody structure like vascular plants, the cell walls of nonvascular plants are crucial for providing the necessary support to maintain their shape and allow them to grow upright.
