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A new conifer genus was recently discovered in northern Vietnam and named Xanthocyparis with two species: X. vietnamensis in Vietnam and X. nootkatensis (= Chamaecyparis nootkatensis) in western North America. This is the first analysis of the leaf essential oil of X. vietnamensis. The oil of X. vietnamensis is dominated by sesquiterpenes and diterpenes. The major components are hedycaryol (1.4-34.4%), phyllocladene (0.9-37.8%), sandaracopimara-8 (14),15-diene (0.7-8.9%), germacrene D (3.7-7.9%), and α-pinene (0.8-14.9%). The oil of Xanthocyparis nootkatensis (Chamaecyparis nootkatensis) is dominated by monoterpenes. The major constituents of X. nootkatensis are limonene (35.4-42.4%), δ-3-carene (11.5-23.4%), α-pinene (8.7-16.3%) and nezukol (3.3-4.8%). The oils differ in many components but share many of the unusual diterpenes. This seems to indicate a rather distant relationship and a long period of divergence. The oil samples of X. vietnamensis were extremely variable (e.g. hedycaryol 1.4-34.4%; phyllocladene 0.9-37.8%) suggesting chemical races or botanical varieties may be present. [ABSTRACT FROM AUTHOR]

Farjon (1) considers the genus Calocedrus as containing just three species, C. decurrens (w. N. America), C. macrolepis (S.W. China, N. Vietnam, N. Thailand) and C. formosana (Taiwan). The leaf oils were analyzed and compared to the oil of the closely related species, Platycladus orientalis (E., N.E. China, Korea, far eastern Russia). The oils of C. macrolepis and C. formosana were very similar, being high in α-pinene (57.2% and 67.1%, respectively) and myrcene (11.2% and 6.2%), but they differed in several smaller components. The oils of C. decurrens from two populations in Oregon and one disjunct population in southern California were high in δ-3-carene (15.2-20.2%), limonene (18.2-23.6%), α-pinene (8.7-15.8%), terpinolene (5.7-8.0%), α-fenchyl acetate (3.5-9.7%), with some cedrol (0.8-1.2%). No large differences in oil compositions were seen between the three C. decurrens populations. Platycladus orientalis (= Thuja orientalis, = Biota orientalis) was found to contain considerable amounts of δ-3-carene (29.8%), cedrol (22.2%), α-pinene (15.1%) and terpinolene (4.9%). Overall, the oil of C. decurrens is as different from C. macrolepis and C. formosana as it is from P. orientalis, suggesting considerable divergence between Calocedrus species, but not between C. macrolepis and C. formosana. These leaf oil analyses support the recognition of C. macrolepis var. formosana in Taiwan as treated in the Flora of China. [ABSTRACT FROM AUTHOR]

The composition of the leaf oils from seven populations of J. sabina L., one population of Juniperus sabina var. arenaria (E. H. Wilson) Farjon were examined for their geographic variation. In addition, the leaf oils of J. chinensis L. and J. davurica Pall. were compared to J. sabina. Juniperus sabina var. arenaria, the sand loving juniper, oil was found to be very similar to that of J. davurica, Mongolia, and J. sabina, on sand dunes in Mongolia. This suggests that J. sabina var. arenaria might be conspecific with J. davurica. Farjon's move (2001) of J. sabina var. arenaria out of J. chinensis is supported. Considerable differentiation was found in populations of J. sabina from the Iberian peninsula. Cedrol, citronellol, safrole, trans-sabinyl acetate, terpinen-4-ol and β-thujone were found to be polymorphic in several populations. [ABSTRACT FROM AUTHOR]