The roots of some plants are not directly or indirectly formed by radicles, but grow from stems, leaves or other parts, and there is no fixed growth site, so they are called adventitious roots. It has the functions of expanding the absorption area of plants and strengthening the fixation or support of plants. In tissue culture, the roots from callus are also called adventitious roots. In forestry and horticulture, the vegetative propagation of willow, grape, rose and begonia can produce a large number of adventitious roots. Adventitious roots of Gramineae plants often grow from tillering nodes and form early, which constitutes the main part of the root system.

Generally speaking, adventitious roots are also roots, but they grow in the same way as ordinary roots. In other words, it can grow roots from branches, stems and leaves by other means, such as cutting. Although the form is different, it is still a root.