Atraphaxis davurica Jaubert & Spach (1844: 15)

Yurtseva, Olga V., Badmaeva, N. K. & Mavrodiev, Evgeny V., 2021, A broadly sampled 3 - loci plastid phylogeny of Atraphaxis (Polygoneae, Polygonoideae, Polygonaceae) reveals new taxa: II. Atraphaxis selengensis spec. nov., and A. davurica Jaub. & Spach from Russian Transbaikalia, Phytotaxa 484 (1), pp. 44-74 : 65-66

2. Atraphaxis davurica Jaubert & Spach (1844: 15) ( Fig. 2A ).

– Tragopyrum lanceolatum auct. non M.Bieb.: Turczaninow (1856: 57), quoad pl. ex Transbaikalia.

– Atraphaxis pungens auct. non (M.Bieb.) Jaub. & Spach, nec (Ledeb.) Jaub. & Spach, quoad pl. ex Transbaikalia: Krylov (1930: 841); Lovelius (1979: 124), Ivanova (1979: 281), Kashina (1992: 109).

Divaricately branched shrub 50–100 cm tall with straight, erect, stout woody shoots 15–55 cm long, 3–4 mm in diam., covered with light-gray bark fibrously splitting and exfoliating, hiding reddish-brown wood. Annual shoots 5–25(50) cm long, mainly lateral, straight, slender, 1–2 mm in diam., rounded, glabrous, creamy or reddish-brown, leafy, with internodes 1–2 cm shorter than leaves, next year lignified and a bit spiny, but easily break off.

Generative shoots 4–6 cm long in lateral positions on short spiny shoots, or 10–20 cm long in lateral positions at long second-year shoots. In both cases the generative shoots are terminated with thyrses 1.5–4(7) cm long with 4–6(10) cymes of 2–3 flowers. Bottom leaf blades are 30–60 × 5–7(10) mm (leaf ratio is 4–6), narrowly elliptical, oblanceolate or spatulate, at base cuneate, gradually narrowed into a petiole 1.0– 1.5 mm long, or almost sessile, glabrous, grayish-green or yellowish-green, abaxially with prominent light green mid vein and oblique laterals. Apex shortly pointed, acuminate, or obtuse; margin flat, slightly revolute, smooth or finely crenulate. Upper leaf blades 4–10 × 0.3–2 mm, linear-lanceolate or subulate, gradually acuminate, margin flat, smooth and slightly revolute. Ochreas 7– 9(12) mm long, equal to internodes or twice shorter, lanceolate-tubular, acute, filmy, brownish at base, whitish-silvery or transparent above, cleft into 2 subulate lacinulas 6–8 mm long, connected with serrate-incised middle portion; each lacinula with a single light-brown vein, deeply serrate-incised at margin, later thorn in threads. Ochreolas 4–7 × 3–4 mm funnel-shaped, filmy, transparent or whitish-silvery, with two subulate lacinulas, each with a light-brown vein, finely serrate-incised at margin. Thyrses bracteose, bracts herbaceous, 4–10 mm long, linear-lanceolate, acuminate. In fruiting, perianth is 8 mm long, with filiform tube 2.5–5 mm long, shortly wedge-shaped at the top, joint to a pedicel 2–4 mm. Outer segments 3,5–4.0 × 2.5–4.0 mm, rotundate to broadly-elliptical, outspread in flowering and reflected to a pedicel in fruiting. Inner segments 5.0–7.0 × 5.0–6.0 mm, rotundate to broadly elliptical, obtuse, green at the middle and white or pinkish at margin, with prominent net of veins. Stamens 8, filaments 2.0 mm long, lanceolate-subulate, suddenly broaden at base. Styles 0.6–0.8 mm long, connated at base to 1/2–2/5, forming a stub, above outspread in flowering and folded together in fruiting, stigmas 0.4–0.6 mm in diam. Mature fruit 2.8–4.5 × 1.5–2.2 mm, almost equal to inner tepals, trigonous, with distinct ribs and lanceolate acuminate faces, black, smooth, glossy, finely micro tuberculate.

Fl.— May–June. Fr.— June–Aug.

Distribution:— RUSSIA,Seleginskaya Buriatia (Zaigraevsky,Selenginsky,Ivolginsky,Dzhidinsky,Tarbagataisky, Kyakhtinsky, Mukhorshibirsky, Kudarinsky districts) and Transbaikal Region (southern part of Chita region). Also continues to neighbouring regions of Mongolia and China, including Lake Dalai (Hulun-Nur) in Inner Mongolia (China).

Ecology:— Mountain stony and rocky steppe slopes, rocks, gravelly ridges. Forms thickets in communities of Caragana , in desert association with Teresken, Ephedra at elevations 500–600 m a.s.l.

Chromosome number:— 2n=48, Buryatia, Selenginsky distr., Selenduma; Novoselenginsk (Selenginsk); right bank of the Chikoy river, sub Atraphaxis pungens (М.Bieb.) Jaub. & Spach ( Ekimova et al. 2009, Muratova et al. 2011, Chepinoga 2014).

Etymology:—Named after Dauria (Dahuria), a mountainous region east of Lake Baikal.

Taxonomic relationships: — Atraphaxis davurica was consistently mistaken for Atraphaxis frutescens (L.) K. Koch and A. pungens Jaub. & Spach , which are not related to A. davurica and absent from Russian Transbaikalia. Atraphaxis davurica resembles A. pungens in the shrubby habit, spiny second-year shoots, bluish-gray leaf blades, compact thyrses, perianth shape and size, black glossy fruits. Atraphaxis davurica differs from A. pungens by longer ochreas, longer lanceolate fruits, micro tuberculate fruit surface, longer styles and spongy stigmas. Atraphaxis pungens has styles 0.4–0.5 mm long terminated with stigmas 0.3–0.4 mm long, bent or beveled outwards. Atraphaxis pungens is distributed in Altai, Tuva, Krasnoyarsk Region, Khakassia, Mongolia, and China. Some specimens of A. davurica resemble A. frutescens in lanceolate leaf blades and rather long thyrses. Atraphaxis frutescens differs by longer thyrses with 10–20 cymes of flowers, lanceolate dark-brown fruits 3–4 mm long, styles 0.3–0.4 mm long and globular stigmas 0.3–0.4 mm in diam.

Figures

FIGURE 2. Atraphaxis davurica (A), A. davurica var. chikoensis (B), A. pungens (C), A. selengensis (D–E) from RUSSIA, and A. frutescens from MONGOLIA (F). A—Buryatia, Mukhorshibirsky d., Podlopatki, Abramova et al. (MW). B—Buryatia, Khentei-Chikoy Highlands, Anagustay, Maximova (LE). C—Khakassia, Askiz d., Kazanovka, Skvortsov (MW). D—Buryatia, Selenginsk, Schukin (LE). E—Buryatia, Selenginsk, Daeva (MHA, Holotype). F—Khovd aimag, Bulgan, Gubanov 7503 (MW).