Chenopodium acerifolium

Mosyakin, Sergei L., 2017, Notes on taxonomy and nomenclature of Chenopodium acerifolium and C. betaceum (C. strictum auct.) (Chenopodiaceae), Phytotaxa 324 (2), pp. 139-154 : 140-141

Chenopodium acerifolium : remaining problems with taxonomy and distribution

Chenopodium acerifolium is a psammophytic species that occurs mainly in sandy alluvial habitats along large rivers of Eastern Europe and adjacent parts of Asia ( Iljin 1952, Mosyakin 1996, 2012, Uotila & Lomonosova 2016 etc.), while it is less common in sandy ruderal habitats. However, Uotila & Lomonosova (2016) treated C. acerifolium in a rather wide sense. My opinion is that in central and northeastern parts of Europe and in Siberia C. acerifolium sensu stricto is probably replaced, at least partly, by other similar and related species or subspecies. In particular, the plants from the Baltic Sea area [ C. klinggraeffii Aellen (1929b: 159) sensu stricto] seem to differ from the typical Ukrainian plants of C. acerifolium in having fruits slightly different in size, as well as in some other characters ( Mosyakin 1996), but the taxonomic value of these minor morphological differences remains obscure at present. Uotila & Lomonosova (2016) also included in C. acerifolium the northern Siberian plants that were sometimes accepted (at least in part) by earlier authors under the name C. jenissejense Aellen & Iljin (in Iljin & Aellen 1936: 873). However, Uotila & Lomonosova (2016) lectotypified the latter name with a specimen of C. karoi (Murr 1923: 97) Aellen (1929b: 149) , thus making C. jenissejense its synonym (Arts. 7.2 and 7.10 of ICN, McNeill et al. 2012). Consequently, if the Siberian plants evidently related to C. acerifolium sensu stricto are recognized as an infraspecific entity of C. acerifolium or as a separate species, there is no name currently available for them.

The records of C. acerifolium from North America ( Weber 1966, Weber & Wittmann 1992; see also discussion in Clemants & Mosyakin 2003) and Saudi Arabia ( Al-Turki & Ghafoor 1996) are clear misidentifications. The description and drawings by Al-Turki & Ghafoor (1996: 201–203, Fig. 5 A–E) leave no doubt that the plant reported from Saudi Arabia does not belong to C. acerifolium . On the basis of the acute-serrate margins of triangular leaves in the depicted plant and the keeled seeds mentioned in the description, it might be some form of Chenopodiastrum murale ( Linnaeus 1753: 219) S. Fuentes, Uotila & Borsch (in Fuentes-Bazan et al. 2012b: 14). The description in Weber (1966: 6), who reported for his plants from Colorado the presence of “strongly pitted seed-coat”, rather indicates C. berlandieri Moquin-Tandon (1840: 23) . Indeed, some forms of C. berlandieri can be superficially similar to C. acerifolium in their leaf shape and general appearance.A field photograph (made by Matt Lavin, Montana State University, Bozeman, Montana, USA) of one of such North American forms was even used to illustrate “ C. album ” in Wikipedia (https://en.wikipedia. org/wiki/ Chenopodium #/media/File: Chenopodium_album _(4032134406).jpg). Additional images made by Lavin in the same locality (available from Flickr: https://www.flickr.com/photos/plant_diversity/4032135322/; https://www. flickr.com/photos/plant_diversity/4032134406/; https://www.flickr.com/photos/plant_diversity/4032133918/ etc.) also suggest that these plants are probably to be identified as C. berlandieri . However, a few specimens of plants similar to the Siberian “ C. acerifolium ” ( C. jenissejense auct .) are known from Alaska ( Clemants & Mosyakin 2003: 298), but their real identity cannot be positively confirmed from the available scarce material.

Dvořák (1987: 562) concluded that C. acerifolium is “a taxon of hybrid origin”. He further stated that “[a]ccording to the morphological characters and to the frequency polygon of the p. g. [pollen grains—S.M.] …there participate in the development of this species: Chenopodium album L., C. diversifolium (Aellen) Dvořák , C. pedunculare Bertol. , C. striatiforme J. Murr , C. suecicum J. Murr. A crossing of a fairly frequent in nature Chenopodium suecicum × subhastatum with Chenopodium striatiforme J. Murr (or rather with Chenopodium × striatialbum Dvořák ) probably takes place”. These assumptions contradict our present knowledge of C. acerifolium (see Feodorova et al. 2015, 2017). This species was reported as a tetraploid with 2n = 36 (see Dvořák 1987, Uotila & Lomonosova 2016 and references therein). However, there are preliminary indications that other chromosome races might be also present within the species group of C. acerifolium (see Feodorova et al. 2015, 2017). Thus, an ancient hybridization event (or events?) probably indeed contributed to the formation of the tetraploid C. acerifolium sensu stricto, but now it represents a lineage phylogenetically rather distinct from the typical C. album and other taxa mentioned by Dvořák (1987). Moreover, judging from the available images ( Dvořák 1987) and a few duplicate specimens at KW, most probably some specimens reported by Dvořák (l.c.) as C. acerifolium from ruderal non-sandy habitats in former Czechoslovakia in fact represent only superficially similar forms of C. album sensu latissimo. The ruderal habitats reported by Dvořák (l.c.) for C. acerifolium in Brno, the Czech Republic (“on the margin of roads and by the fences in plant communities of Polygonion avicularis Br. Bl. 1931”: Dvořák 1987: 571), definitely do not correspond to typical habitats of C. acerifolium sensu stricto in Ukraine and the European part of Russia.

Recently the species group of C. acerifolium and related taxa attracted much attention of taxonomists because of still remaining nomenclatural and taxonomic problems (see e.g., Uotila & Lomonosova 2016) and also because of recent hybridization events observed in nature with participation of this species ( Mosyakin 1996, 2012, Feodorova et al. 2017).