Fig. 2

Raman imaging of the cuticle of Norway spruce based on band integration and extracted average spectra of the visualized chemically different regions a The outer lipidic layers are visualized by integrating the band at 1120 cm⁻¹ and 1440 cm⁻¹ and b the extracted average spectra confirm the lipidic character, but also include bands attributed to aromatics. c Integrating the band at 1490 cm⁻¹ visualizes a pointwise accumulation of Calcium oxalate d as confirmed by the bands at 1490, 1463 and 895 cm⁻¹. e Integrating different aromatic bands shows their distribution throughout the cuticle and epidermal layer and f extracted average spectra confirm that different aromatic components play a role g Integrating the characteristic cellulose band at 380 cm⁻¹ displays the lower cuticle and h the derived average spectrum confirms carbohydrates together with aromatics