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Abstract:In order to get better knowledge about the volatiles produced by Xanthocyparis vietnamensis, a species recently discovered in Vietnam, its wood oil has been analyzed by a combination of chromatographic (GC, CC) and spectroscopic (GC-MS, 13 C-NMR) techniques. Forty components that accounted for 87.9% of the oil composition have been identified. The composition is dominated by nootkatene (20.7%), 11,12,13-tri-nor-eremophil-1(10)-en-7-one (17.2%), γ-eudesmol (5.1%), nootkatone (4.7%), valencene (3.5%) and 13-nor-eremophil-1(10)-en-11-one (2.6%). The structure of two new compounds-10-epi-nor-γ-eudesmen-11-one and 12-hydroxy-isodihydroagarofuran-has been elucidated, while 11,12,13-tri-nor-eremophil-1(10)-en-7-ol is reported as a natural product for the first time. The composition of X. vietnamensis wood oil varied drastically from those of leaf oils, dominated by hedycaryol (34.4%), phyllocladene (37.8%) or by pimara-6(14)-15-diene (19.4%).

Three species, Bulbophyllum layae, B. metallica and B. papilligerum (all from sect. Cirrhopetalum) are described as new for science. All of these novelties are local endemics of limestone areas of northern Vietnam. Additionally, three species, B. alcicorne (sect. Brachystachya), B. psittacoglossum and B. yunnanense (both from sect. Sestochilus) are recorded for the flora of Vietnam for the first time. These species have wide distribution in mainland Asia. Data on ecology, phenology, distribution, brief relevant taxonomic notes, as well as color photographs, analytical plates of the type and voucher specimens are provided for all reported taxa. Lectotypification is provided for B. yunnanense.