Atriplex sect. Obione (Gaertn.) Reichenb., Uebers. Gew.-Reich.: 164 (1828); C.A.Mey. in Ledeb. et al., Fl. Altaic. 4: 315 (1833).

Sukhorukov, Alexander P., Kushunina, Maria & Sennikov, Alexander N., 2022, A new classification of C 4 - Atriplex species in Russia, with the first alien record of Atriplex flabellum (Chenopodiaceae, Amaranthaceae) from North Siberia, PhytoKeys 202, pp. 59-72 : 59

Atriplex sect. Obione (Gaertn.) Reichenb., Uebers. Gew.-Reich.: 164 (1828); C.A.Mey. in Ledeb. et al., Fl. Altaic. 4: 315 (1833).

Obione ≡ Obione Gaertn., De Fruct. 2: 198 (1791).

Obione Atriplicina ≡ Obione sect. Atriplicina Moq., Chenop. Monogr. Enum.: 70 (1840), nom. inval. (Art. 22.2).

Atriplex Obione ≡ Atriplex subgen. Obione (Gaertn.) Hook.f., Student Fl. Brit. Isl.: 320 (1870); Volkens in Engler & Harms, Nat. Pflanzenfam. 3: 66 (1893).

Atriplex Atriplicina ≡ Atriplex sect. Atriplicina Volkens in Engler & Harms, Nat. Pflanzenfam. 3: 66 (1893), nom. illeg. (Art. 52.1).

Obione Protobione ≡ Obione sect. Protobione Aellen, Verh. Naturf. Ges. Basel 49: 133 (1938), nom. inval. (Art. 22.2). Type species: Obione muricata Gaertn. (≡ Atriplex sibirica L.).

Atriplex = Atriplex [unranked] Sclerocalymma Asch., Fl. Prov. Brandenburg 1(2): 578 (1864), syn. nov.

Atriplex Sclerocalymma ≡ Atriplex sect. Sclerocalymma (Asch.) Asch. & Graebn., Syn. Mitteleur. Fl. 5(1): 139 (1919).

Atriplex Roseae ≡ Atriplex sect. Roseae Aellen, Bot. Jahrb. Syst. 70(1): 39 (1939), “Rosea”, nom. illeg. (Art. 52.1). Type species: Atriplex rosea L.

Atriplex = Atriplex [unranked] Argenteae Standl. in Britton, N. Amer. Fl. 21: 46 (1916), syn. nov.

Atriplex Argenteae ≡ Atriplex subsect. Argenteae (Standl.) S.L.Welsh, Rhodora 102: 420 (2001). Type species (Art. 10.8): Atriplex argentea Nutt.

Description.

Annuals; inflorescences leafy; glomerules loosely arranged.

Native distribution and species.

Members of the section occur in steppes, semi-deserts and mountains of Central Asia (e.g. A. altaica , A. centralasiatica , A. pamirica , A. sibirica ), in the Aralo-Caspian floristic region ( A. sphaeromorpha ), in the Mediterranean ( A. rosea ), and in North America ( A. argentea Nutt.). Five species are native to Russia ( A. altaica , A. centralasiatica , A. sibirica , A. sphaeromorpha , and A. rosea ). The Central Asian species ( A. altaica , A. centralasiatica , A. sibirica ) are mostly confined to mountain steppes and screes in South Siberia, but A. centralasiatica and A. sibirica can be found also in saline and ruderal habitats. Atriplex rosea and A. sphaeromorpha are typical lowland species with similar morphology but different distribution patterns. The first species, with predominantly Mediterranean distribution, was considered native in the southern part of Eastern Europe ( Medvedeva 1996), whereas we treat it as native only in Krasnodarsky Kray, where it occurs near the shore of the Black Sea and in ruderal places further inland ( Sukhorukov 2006; Zernov 2006). Atriplex sphaeromorpha is mainly distributed in steppes and semi-deserts of Kazakhstan, with very scattered records in Orenburg and Saratov Oblast, as well as in the North Caucasus ( Sukhorukov 1999, 2006). In these regions, A. sphaeromorpha could potentially require conservation action according to the IUCN guidelines ( IUCN 2022) because of a high level of anthropogenic disturbance to Eurasian grasslands. The native and alien ranges of all Russian species of A. sect. Obione are displayed in Fig. 1A-E .

Taxonomic notes.

The synonymisation of Atriplex sect. Obione with A. sect. Sclerocalymma and A. subsect. Argenteae is undertaken here for the first time. Atriplex powellii S.Watson, previously considered as a close relative of A. argentea ( Standley 1916; Welsh 2001), occupies a distant phylogenetic position ( Žerdoner Čalasan et al. 2022).

Nomenclatural notes.

The name A. sect. Obione has usually been credited to Meyer (1833), who accepted this subdivision in 'Flora Altaica’. However, the first author who segregated this section within Atriplex was Reichenbach (1828). He accepted the name and provided an indirect reference to the basionym as " Obione . G." The infrageneric taxa accepted by Reichenbach (1828) were explicitly ranked as sections, as evidenced by a footnote on page 184 in this work. Similarly, Hooker (1870) was the first to accept A. subgen. Obione , which was explicitly ranked by him. On the contrary, Ascherson (1864) developed complex infrageneric systems that included at least three ranks, with names at all of these ranks, and made no note of their ranking; such classifications are to be treated as unranked (Art. 37.3).

Figures

Figure 1. Schematic distribution areas of C 4 - species of Atriplex native to Russia A A. altaica B A. centralasiatica C A. rosea D A. sibirica E A. sphaeromorpha F A. tatarica. Green - native distribution range, yellow - alien distribution not confirmed after 1930 s, orange - alien distribution confirmed after 1930 s.