Taraxacum angarense Kirschner & Štěpánek, 2023

Kirschner, Jan & Štěpánek, Jan, 2023, A taxonomic revision of Taraxacum sect. Dissecta, a continental steppe group common in Siberia and adjacent regions of Central Asia, Phytotaxa 590 (1), pp. 1921-1935 : 1921-1935

23. Taraxacum angarense Kirschner & Štěpánek , sp. nov.

Type:—[ RUSSIA] Sibiria merid., urbs Irkutsk, graminosis in urbis centro, prope ecclesiam haud procul a deversorio Angara [Irkutsk, grasslands in the city centre, near the church, in the vicinity of the Angara Hotel], 25 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2692 ( PRA, no. det. 35981, holotype; isotype: PRA, no. det. 36704) .

Etymology:—The name is derived from the fact that this species occurs at three mutually remote localities situated along River Angara.

Exsiccates:— Taraxaca Exs., no. 1369–1371.

Diagnosis:—Plantae inter sectionum Dissectorum et Borealiorum intermediae, foliis profunde pinnatisectis, lobis lateralibus foliorum remotis patentibus angustis, phyllariis involucralibus exterioribus erectis usque patentibus, anguste lanceolatis vel lanceolatis, marginibus pallidis, luto-viridibus, 0.5–0.6 mm latis, apice atrocornutis, cornibus brevibus obtusis, acheniis pallide stramineobrunneis, corpore in pyramidem subcylindricam subabrupte transeunte bene dignoscendae.

Plants small to almost medium-sized, usually to 9–13 cm tall. Petiole narrow, unwinged, or narrowly winged in outer leaves, purple (rarely green), arachnoid; plant base with sparse yellowish hairs, tunic only slightly developed. Leaves deep green, sometimes dark green, sparsely arachnoid, mainly along the mid-vein, with interlobes bordered or blotched dark brown-purple, oblanceolate in outline, usually 6–11 × 1.5–3.5 cm, deeply pinnatisect, with lateral segments in (3) 4 (5) pairs, patent to ± forward-pointing, usually with broad base, on the distal margin abruptly narrowed in a linear to linear-lingulate distal part, entire or with 1–2 lobules or teeth on the broad basal part, concave, proximal margin straight to convex, entire or with a single subbasal tooth; terminal segment tripartite, with a linear-triangular distal part and patent to forward-pointing basal lobules, ± entire; interlobes often bordered or even blotched dark brown-purple, 2–3 mm wide, entire or sparsely lobulate and/or dentate; mid-vein usually purplish, sometimes pale green. Scapes brownish green, arachnoid, ± equalling leaves. Capitulum yellow or lighter yellow, 3–4 cm wide. Involucre dark green, 9–10 mm wide and rounded at base. Outer phyllaries quite numerous, usually 14–17, erect, erect-patent or almost patent, almost not imbricate, narrowly to broadly lanceolate, usually (5–) 6–7.5 (–8.5) × 1.8–2.6 mm, usually dark green to blackish green, marginal and distal parts usually suffused purplish, border sharply delimited, narrow, 0.1–0.2 (–0.3) mm wide, rarely, in the basal part of phyllaries, a yellow-green border to 0.5–0.6 mm wide, margin ± glabrous, apex almost blackish, usually suffused purple, with a black horn to ca. 0.5 mm high; inner phyllaries usually 14–15 mm long, flat to corniculate. Outer ligules flat, striped light grey-purple outside, inner ligule teeth faintly greyish-purplish. Stigmas darker discoloured, yellow-green, with dark pubescence outside. Pollen present, pollen grains irregular in size. Achenes light greyish stramineous-brown, 3.7–4.4 × 0.8–0.9 mm, body subsparsely but distinctly spinulose and squamulose (spinules erect-patent), subabruptly narrowing into a subcylindrical cone (0.7–) 0.8–1.0 (–1.1) mm, ca. 0.3 mm thick at base, 0.2–0.25 mm distally, often with 1–2 spinules on the proximal 1/3 of the cone; beak 9–10 mm, pappus 6–6.5 mm, white to yellowish white. – Agamosperm. – Fig. 26 .

Diagnostic notes:—The relatively narrow, lanceolate, dark and horned outer phyllaries may point to T. sect. Borealia but the horns are relatively short, obtuse, the cone is subcylindrical, and the leaves have a characteristic shape of T. sect. Dissecta . The character combination places this species in an intermediate position between the above two sections, closer to the latter.

Distribution and habitat:—At several sites between Lake Baikal and Bratsk on the Angara River, Siberia. Gravelly and sandy shore habitats and dry grasslands on adjacent slopes, between 400 and 500 m a.s.l.

Specimens examined:—[ RUSSIA, Irkutskaya oblast] S. Siberia, city of Irkutsk, grasslands in the centre, near the church, not far from Angara hotel, 25 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2692 ( PRA, no. det. 36704, with duplicates). – Irkutsk City, lawns between “Politekhnicheskiy Institut” and “Akademkniga” [ca. 52° 15’ N, 104°16’ E], 25 Oct 1985, J. Štěpánek & J. Kirschner, cultivated as JŠ 1584/6 ( PRA, no. det. 36705). – Irkutsk, Lake Baikal, pastures in the vicinity of the origin of River Angara, 26 Oct 1985, J. Štěpánek & J. Kirschner, cultivated as JŠ 1574/32 ( PRA, no. det. 36706). – S. Siberia, town of Bratsk, west shore of the “Bratskoe More” reservoir, about 2 km from the dam, 28 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2698 ( PRA, no. det. 36708). – Less certain identification:—City of Irkutsk, Baikal Lake, village of Listvyanka, shore of Lake Baikal , between the village and the origin of Angara River , 26 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2528 ( PRA, no. det. 36710) .

Figures

FIGURE 26. Taraxacum angarense. A, General habit; B, Achenes (both from PRA, no. det. 35981, holotype).