What is the piliferous layer?

In roots, absorption of water and minerals mostly occurs in the :

Roots have thorny branches in

Which one is the largest root parasite?

Roots obtain oxygen from air in the soil for respiration. In the absence or deficiency of $O_{2}$,root growth is restricted or completely stopped. How do the plants growing in marsh lands or swamps obtain their $O_{2}$ required for respiration?

'Pneumatophores' are present/common in