Chemosystematic studies in the genus Pseudotsuga. I. Leaf oil analysis of the coastal and Rocky Mountain varieties of the Douglas fir

Abstract

The volatile leaf oils of the coastal and Rocky Mountain varieties of the Douglas fir were found to have distinctive terpene compositions. The relative amounts of l-β-pinene, sabinene, 3-carene, α- and γ-terpinene, terpinolene, l-terpinen-4-ol, citronellol, citronellyl and geranyl acetate (relatively large in the former variety); and santene, tricyclene, l-camphene, limonene, and l-bornyl acetate (relatively large in the latter variety) may serve as distinguishing features. n-Hexenal, l-α-pinene, α- and β-phellandrene, linalool, fenchyl alcohol, and l-α-terpineol were also isolated. The within-tree and within-population variation of the amounts of these terpenes as well as populational differences from Calgary through the foothills to Revelstoke were small. Intermediate compositions were encountered as far west as the Cascades and one may distinguish clearly between interior and coastal intermediate terpene patterns. Between Keremeos and Hedley the terpene pattern was essentially that of the Rocky Mountain variety whereas at Jasper intermediate patterns leaning towards coastal intermediates were recorded. Analysis of the leaf oils from five different provenances of coastal populations indicated that a north–south cline may exist. Provenance samples showed conclusively that the terpene patterns are genetically controlled and are not influenced by ecological factors. Hence these terpene patterns may serve as a genetic guide and provide a quantitative measure of coastal, intermediate, and Rocky Mountain types of populations.