ANALYSIS OF FOLIAR MONOTERPENOID CONTENT IN THE CALIFORNIA BAY TREE, UMBELLULARIA-CALIFORNICA, AMONG POPULATIONS ACROSS THE DISTRIBUTION OFTHE SPECIES

Mature foliage of 110 trees from 11 populations of Umbellularia califo rnica across its geographic range including diverse habitats were anal yzed for monoterpenoid compositional variation by gas chromatography. Three previously unreported compounds for U. californica were identifi ed: thujene, cis-sabinene hydrate, and trans-sabinene hydrate, however , all being minor components (< 2.0% of the total composition). One-wa y ANOVA for each individual compound showed differing significant leve ls of variation among the 24 compounds analyzed, high (P = 0.001) for 14 compounds, moderate (0.001 < P < 0.01) for umbellulone, and no sign ificance for (P < 0.05) for seven compounds. Stepwise Discriminant Ana lysis of the variance in the entire data set reduced the number of var iables to 15 (significance associated with Wilks' Lambda P < 0.001). C anonical Discriminant Analysis by individual tree failed to completely separate any of the source populations. Average Linkage Cluster Analy sis demonstrated that U. californica monoterpenoid composition apparen tly is genetically controlled with little sig nificant geographic vari ation. Furthermore, the monoterpenoid compositional variation data did not support maintaining the subspecies designation for U. callifornic a fresnensis Eastw. The lack of monoterpenoid variation among populati ons across a wide geographic distribution and diverse habitats enables generalization of results from studies of mammalian herbivory on U. c alifornica.