Complex tissues are specialized groups of cells in plants that work together to perform specific functions. They are primarily composed of two main types: xylem, which transports water and nutrients from the roots to the rest of the plant, and phloem, which distributes sugars produced during photosynthesis. These tissues are essential for the plant's growth and overall health. In addition to xylem and phloem, complex tissues also include vascular tissue, which is responsible for the movement of fluids and nutrients. These tissues are crucial for maintaining the plant's structure and enabling it to adapt to its environment, ensuring efficient resource distribution throughout the organism.