In $Rhizophora$,roots are modified to form

The edible part of the turnip ($Brassica$ $rapa$) is a ........

Photosynthetic roots are recorded from

The calyptrogen of the root apex forms

The layer which separates velamen (a spongy tissue in epiphytic roots of some orchids for absorption of atmospheric moisture) from the cortex is called:

Velamen takes part in