Complex tissues are specialized groups of cells in plants that work together to perform specific functions. They are primarily found in vascular plants and include two main types: xylem and phloem. Xylem is responsible for transporting water and minerals from the roots to the rest of the plant, while phloem distributes sugars and nutrients produced during photosynthesis. These tissues are made up of different cell types, each contributing to the overall function. For example, xylem contains vessel elements and tracheids, which help in water conduction, while phloem consists of sieve elements and companion cells that facilitate nutrient transport. Together, these complex tissues support plant growth and development.