Root: Metamorphosis of the roots
In some cases the shape of the root, and also its function, differ from the common type now described.
In fact, there are some roots, called aerial roots which have a large surface area, but are free of absorbent hairs.
They never reach the ground and therefore absorb moisture from the atmosphere.
Roots of this type develop only in hot-humid environments such as, for example, the equatorial forest (eg epiphytic orchids).
There are also roots that descend from the branches of trees up to the ground and perform a function of support towards them: they are called columnar roots (eg Ficus religiosa).
Some plants, typical of wetlands, have particular roots that, rising from the ground, grow upwards; they are called respiratory roots because their function is to provide oxygen for the partially submerged plant's respiration (eg Taxodium). In the roots of aquatic plants we note the lack of root hairs, since all the immersed parts can perform the function of absorption.