Morphology, anatomy and morphogenesis of seed cones of Cupressus vietnamensis (Cupressaceae) and the taxonomic and systematic implications

•Xanthocyparis seed cones show all features typical for Cupressus.•C. vietnamensis has a small Cupressus seed cone type.•C. vietnamensis is a true Cupressus species.•Xanthocyparis should be merged into the genus Cupressus.•No arguments for a separation of C. vietnamensis from Cupressus were found.

The morphology, anatomy and morphogenesis of seed cones in Cupressus vietnamensis are investigated at pollination time and maturity to fill the gaps in the knowledge of this taxon. The results clearly point out that the seed cones show all the features of a typical seed cone in Cupressus and do not show any pecular pattern. Unique features proposed to be exclusively developed in Cupressus vietnamensis and missing in seed cones of other species of Cupressus were not found. In fact, the seed cones of C. vietnamensis represent a small form of typical seed cones in Cupressus and are structurally identical to those of C. nootkatensis. The results clearly indicate that C. vietnamensis is a true Cupressus, although with conspicuously small seed cones. No reason was found to recognize of this taxon as being distinct from Cupressus.