Atraphaxis

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 : 63-64

Key to the species of Atraphaxis growing in Mongolia, Altai, Southern Siberia and Russian Transbaikalia

1. Perianth with two inner and two outer segments, 6 stamens, lenticular fruit with two styles ...........................................................2

– Perianth with three inner and two outer segments, 8 stamens, trigonous fruit with 3 styles .............................................................4

2. Leaf blades shortly puberulent abaxially.......................................................................................... A. canescens Bunge (1839 : VII)

– Leaf blades glabrous...........................................................................................................................................................................3

3. Inner perianth segments reniform, 7–9 × 7–11 mm, 1.5–2 times longer than fruits ............................................................................ ........................................................................................................................................................ A. compacta Ledebour (1830: 55)

– Inner perianth segments rotundate, 5–6 × 7–8 mm, almost equal to fruits .................................... A. replicata Lamarck (1783: 329)

4. Outer perianth segments 1.5 times shorter than inner segments, outspread in fruiting. All perianth segments depart from a cupshaped extention of a filiform perianth tube 0.7–1.0 mm long joint to a pedicel 2.0–3.0 mm long .................................................... .................................................................................................................................... A. selengensis Yurtseva & Mavrodiev sp. nov.

– Outer perianth segments 2–3 times shorter than inner segments, reflected to a pedicel in fruiting. All the perianth segments depart from the top of a wedge-shaped extention of a filiform perianth tube 2.5–6.0 mm long, joint to a pedicel of equal length............... ...........................................................................................................................................................................................................5.

5. Subshrubs or shrubs with straight elongated annual shoots, never spiny, terminated with thyrses 5–15 cm long with 8–12 cymes of flowers. Styles 0.3 mm long..............................................................................................................................................................6.

– Shrubs with sturdy second-year shoots and lateral branches terminated with compact lateral thyrses 1.5–4 cm long with 4–6 cymes of flowers, sometimes spiny. Styles 0.3–0.8 mm long ......................................................................................................................7.

6. Subshrubs 20–70 mm tall. Leaf blades oblanceolate, pinnate-reticulate ................................................... A. frutescens (L.) K.Koch

– Schrubs 100 cm tall. Leaf blades have no net of veins, but bear longitudinal wrinkles on the upper side.......................................... ..................................................................................................................................................................... A. virgata (Regel) Krasn.

7. Annual shoots and leaf blades shortly papillose below. Leaf blades rotundate to broadly elliptical, 7–15 mm long, leaf ratio 1.5–3. Mature fruits brown, almost 2–3 times shorter than inner perianth segments ..................................................................................... ...................................................................................................................................................... A. laetevirens Ledebour (1830: 75)

– Annual shoots and leaf blades glabrous. Leaf blades broadly elliptical to linear-lanceolate, 15–60 mm long, leaf ratio 3–7. Mature fruits black, glossy, twice shorter or equal to inner perianth segments .............................................................................................8.

8. Ochreas at vegetative annual shoots 4–6 mm long. Fruits smooth and glossy, twice shorter than inner perianth segments. Styles 0.3–0.4 mm long, in flowering elongated and flattened, beveled out and bent to the ovary. Khakassia, Mongolia, Altai, Tuva ........ ................................................................................................................................................... A. pungens (M.Bieb.) Jaub. & Spach

– Ochreas at vegetative annual shoots 6–9(11) mm long. Fruits finely pitted or microtuberculate (× 4), glossy, almost equal to inner perianth segment. Styles 0.6–0.8 mm long, stigmas extended to ends, spread in flowering and congested in fruiting. Transbaikalia .................................................................................................................................................................................... 9.

9. Second-year shoots light-gray, spiny or not. Leaf blades glaucous to bright-green or yellowish-green, spatulate or oblanceolate, with maximum width near the top, long-petiolate.............................................................. A. davurica Jaub. & Spach var. davurica

– Second-year shoots dark-gray, unarmed. Leaf blades bright-green, broadly elliptical to narrowly oblong, with a maximum width near the middle, short-petiolate ............................................................ A. davurica var. chikoensis Yurtseva & Mavrodiev var. nov.