The plant world is conveniently separated into two major groups: nonvascular plants and vascular plants. The nonvascular plants include the bryophytes, while the vascular plants include the ferns, gymnosperms, and angiosperms (see Chapter 19). The nonvascular plants have no internal transport system. The vascular plants do have such a system, and they are more structurally and functionally complex.
Highly specialized tissues occur in the vascular plants. (A tissue is a group of cells working together to carry out a specialized function.) The tissues are organized into specialized organs called roots, stems, and leaves. The internal vascular system, composed of xylem and phloem, is housed within these organs and connects the organs to one another.
Different combinations of tissues make up the organs of a vascular plant. The four types of tissues are as follows: vascular tissue, ground tissue, dermal tissue, and meristematic tissue.