Autofluorescence emission intensity from a thin section of corn grain tissue. Endogenous autofluorescence in plant tissues arises from a variety of biomolecules, including chlorophyll, carotene, and xanthophyll. In the violet region, chlorophyll has an absorption band with a high extinction coefficient and produces a significant amount of fluorescence when excited with wavelengths between 390 and 420 nanometers. Note the absence of spectral bleed-through from autofluorescence emission in the green and red spectral regions.