roots arising from roots or stems and having no connection to apical meristems.
adventitious roots (Wikipedia)
This article is missing information about details on function, root-environment/soil interactions.March 2016) ( |

Primary and secondary roots in a cotton plant
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. Roots can also be aerial or aerating, that is, growing up above the ground or especially above water. Furthermore, a stem normally occurring below ground is not exceptional either (see rhizome). Therefore, the root is best defined as the non-leaf, non-nodes bearing parts of the plant's body. However, important internal structural differences between stems and roots exist.