Pneumatophores are found in the vegetation which is found in marshy and saline lakes.
Knees or Pneumatophores are specialized roots developing in mangrove plants.
These are found growing in saline marshes, roots growing vertically upwards.
They are negatively geotropic.
The air enters the roots via pneumatophores, small breathing pores found on the tips of the vertical roots. Some of these are Heritiera, Rhizophora, etc.