What is meant by modification of root?

What is meant by modification of root? What type of modification of roots is found in the
(a) Banyan tree, (b) Turnip, © Mangroove trees ?

Modifications are the morphological changes (in shape, form or structure) in roots to perform certain special functions other than or in addition to the normal functions.
(a) Banyan tree : Prop roots are found in Banyan tree
(b) Turnip : It is a napiform root which is almost globular or top shaped and tapers abruptly towards the apex.
© Mangroove Tree : The roots found in mangroove trees are pneumatophores.