Ferns are in the kingdom of Plants. They are classified as being vascular plants. The vascular system in a plant is what is responsible for transporting water and nutrients throughout the plant. Vascular tissue also makes the plant tissue stronger and more resilient. This vascular tissue contains xylem and phloem. Xylem brings water and nutrients into plants and phloem moves food into some plants. Ferns have roots, stems and leaves just like other plants except generally the stem of a fern is underground rather than above ground. Ferns can also vary widly in size from very small ferns to ferns several meters tall.