Structural conditions of mesophyll cells of Pinusponderosa var. scopulorum after SO2 fumigation

Ultracytopathological observations on Pinusponderosa var. scopulorum needles after long-term fumigation with SO2 showed several symptoms. These included lack of starch grains, vacuoles with darkly stained deposits, occurrence of large droplets of lipid-like material, and rounded shape of the chloroplasts (also associated with swelling of thylakoids).