Question

What is the role of large bundle shealth cells found around the vascular bundles in $C_4$ plants?

Answer 1

In C4 plants, the bundle sheath cells found around the vascular bundles increases number of chloroplasts and are the site of the Calvin cycle.

C4 plants are able to tolerate high temperature due to photorespiration is minimal compared to C3 plants, and CO2 is actively concentrated in these bundle sheath cells.

Bundle sheath extensions appear to be an adaptation to saving water and to protecting the mesophyll against water stress not vascular tissue from high light intensity.

C4 plants avoid photorespiration by using another enzyme called PEP during the first step of carbon fixation. Therefore, they do not provide site for photorespiratory pathway.