Fig. 1.

Raman imaging of native plant cuticles. a After sampling the needles are kept frozen, also during cutting of microsections with the cryo-microtome. Cross sections (20 µm thick) are scanned using a Confocal Raman microscope. The region of interest included the adaxial cuticle together with the underlying epidermal layer. b The resulting hyperspectral data cube is analysed using three different approaches: Univariate band integration, clustering spectra based on similarity and retrieving the most pure components based on Non-negative-matrix-factorizations