Geographic variability of monoterpenes from cortex of Pseudotsuga menziesii

Cortical oleoresin from over 300 trees of Pseudotsuga menziessii (Mirb.) Franeo has been collected in localities throughout the entire US-Canadian range of this species and analyzed for monoterpenoids. Striking chemical differences particularly in sabinene and rt-pinene percentages between the 'pure' coastal var. menziessii and the inland var. glauca (Beissn.) Franeo have been encountered. Intergradation betwcen the two varictics was extensive in Canada, spanning the area between coastal ranges and the Canadian Rockies, but was less pronounced in central Oregon, where only a few chemically intermediate trecs could be located. Less intensive, albeit definite, chemical differences were found between olearesins collected in the northern inland (var. caesia Aschers. and Graebn.) and the southern inland (var. glauca Schneider) localities. California populations from Sierra Nevada appeared to represent a separate chemical racc, closcr to inland than to coastal variety. The variations found are discussed on the basis of cvolutionary pressures exerted by Wisconsin glaciations.