Aerial root

Aerial roots are usually in the form of epiphytic plants. They are used for water and nutrient uptake from the air and partly the fixation on the substrate. These roots surrounds eg orchids a velamen radicum called spongy cell layer. In case of rain or high humidity, these cells engorge with water. In the second image of the cross section of an aerial root Orchid is shown in about 400 - fold magnification. The red-colored cells are lignified and permeable and allow the nutrients and moisture to penetrate into the root.

An increased formation of aerial roots can be caused by the fact that the plant is not sufficient to supply the ground roots. Also insufficient climbing on a climbing plant can cause this effect.

Mangroves of the genus Rhizophora form (in addition to the root springing arcuate stilt roots ) on their branches often vertically hanging aerial roots, which can take over support function when reaching the substrate. Similar roots are also found in other species of trees, such as figs ( Moraceae ).

Individual air roots can be cut off if they interfere, but it can not all be cut off. In orchids maximum dead air roots should be removed.