ИСТИНА

Recent molecular investigations strongly suggest that the genus Chenopodium sensu lato unites morphologically similar but phylogenetically distant taxa. The genera Blitum (tribe Anserineae) and Oxybasis (Chenopodieae) provide an example by virtue of homoplastic reduction in number of perianth segments. The exact definitions of these genera are still unclear, and the morphological characters do not play an important role in their diagnostics and delimitation. Some enigmatic taxa with pending taxonomy have not been included in the molecular analysis. Based on morphology, Chenopodium antarcticum has been recently transferred into Oxybasis (O. antarctica), and Monolepis is now considered to be a synonym of Blitum. We have investigated several species with pending taxonomy based on both molecular (using three markers: ITS, rbcL and trnH-psbA) and carpological methods. Chenopodium antarcticum (Oxybasis antarctica) does indeed belong to Blitum (B. antarcticum) as proposed by Hooker; the systematic placement of Monolepis asiatica or M. nuttallianua in the genus Blitum is confirmed. However, the third Monolepis species – M. spathulata transferred into Blitum (B. spathulatum) – is a sister group to all Chenopodieae. We note that all Blitum species in the re-defined genus have the seed-coat testa lacking “stalactites” in the cells, and the genus is distinguished by the easily visible protoplast; in contrast, all Oxybasis representatives and Monolepis spathulata possess vertical stalactites in the outer cell walls of the testa, and the protoplast is reduced to small strips (a feature of almost all Chenopodieae). This peculiarity in the seed-coat testa is a single useful trait separating Blitum and Oxybasis unambiguously.