The concentrations of the glucoside picein and its aglucone piceol (4-hydroxy acetophenone) in the needles of Norway spruce (Picea abies (L.) Karsten) are considered indicators of plant stress. By use of two clones and a natural population of Norway spruce it was shown that the picein concentration was dependent on the site and the provenance of the trees. No effects were observed by normal treatment with the herbicides atrazine, glyphosate, and hexazinone, or by drought. The significance of different environmental factors is discussed.
