The distribution of lignin in the cell wall of conifer tracheids was determined by UV-VIS microspectro-photometer. Wood sections of one micron thickness were measured between the wavelength 240 and 700 nm. Spectral analyses revealed that the conifer lignin associated with the tracheid secondary wall and middle lamella is composed of guiacylpropane units which exhibit a characteristic UV absorption maximum at 280 nm. Therefore, in addition, ultrathin sections were exclusively scanned with this characteristic wavelength. Four examples of application are presented: (1) l the lignin contents of the different cell wall regions of fresh spruce wood, (2) the UV-characterization of highly lignified S2-layers in compression wood, (3) a specific pattern of lignin distribution and its derivatives during degradation by white-rot fungi and (4) the detection of accessory compounds (e.g. podocarpic acid) in the lumen and the cell walls of Podocarpaceae species. Finally, the prospects for actual research concerning detection of accessory compounds from hardwoods are given.

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