Chemosystematic studies in the genus Picea (Pinaceae). IV. The introgression of white and Engelmann spruce as found along the Bow River

The leaf oil of the spruces found along the Bow River from the foothills to Bow Summit was analyzed by gas–liquid chromatography. The terpene distribution patterns obtained were compared with the morphological data derived from the cones and twigs of the same trees. The results obtained confirm that typical white spruce occurs at low elevation whereas active hybridization with Engelmann spruce occurs at levels above 5000 ft. Although the trees at the timberline (7200 ft) had predominantly Engelmann spruce characteristics, much variation from tree to tree was encountered. In the terpene composition the quantitative variation was too large to permit conclusions about a typical Engelmann spruce terpene distribution pattern.