Epicuticular Wax Formation on Needles of Picea abies and Pinus Cembra
Needles (plucked from trees at the alpine timberline) still enclosed in the buds and after flushing were examined by scanning electron microscopy. First wax protrusions emerge from the cuticle on the rim of the subsidiary cells and cover the slightly sunken guard cell mother cells. The stomata are fully developed and covered by the first wax layer before bud break. Crystallization of chromatographically isolated wax components show the wax structure to vary with its composition. Wax secretions of different structure seem to follow each other (Günthardt-Goerg 1985). This presentation intends to show the wax composition during the first months after flushing and when the different wax components are formed. At the alpine timberline the wax layer has to build up in a short vegetation period (July – October) to protect the young needles in the coming winter. The wax layer is poorly developed and/or has another composition under unfavourable conditions. This fact constitutes one reason for the needles’ death through winter desiccation.
KeywordsSecondary Alcohol Picea Abies Subsidiary Cell Young Needle Alpine Timberline
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