Taraxacum pseudocompitale Kirschner & Štěpánek, 2025

Kirschner, Jan, Štěpánek, Jan & Buryy, Vladimir V., 2025, Towards a revision of Taraxacum sect. Borealia (Compositae, Crepidinae) in Siberia and the continental Far East, with special reference to the dandelions of the Altai and Kamchatka, Phytotaxa 679 (1), pp. 1-147 : 124-127

54. Taraxacum pseudocompitale Kirschner & Štěpánek , sp. nov.

Type:—[ RUSSIA] Sibiria merid., urbs Irkutsk, lacus Bajkal, pagus Listvjanka , in decl. stepposis supra portum in pago Listvjanka , 26 Oct 1985, J . Kirschner & J . Štěpánek , cultivated from achenes as JŠ 2549, collected in 1988 ( PRA, no. det. 37778; isotypi: PRA) .

Etymology:—Similar to Taraxacum compitale .

Diagnosis:—A Taraxaco compitali acheniis tenuibus corpore superne subsparse squamuloso, in pyramidem subcylindricam persensim transeunte, phyllariis exterioribus arcte adpressis, conspicue late marginatis, et foliis forma differt .

Plants medium-sized, usually 10–15 cm tall. Plant base without tunic, subglabrous; petiole winged to broadly winged, pale greenish or ± purplish along mid-vein. Leaves deep green to ± dark green, later often slightly suffused brownish-purplish, ± glabrous, oblong to narrowly oblong in outline, ca. (5–) 9–12 (–14) × (1.2–) 2.0–2.5 (–3.5) cm, with conspicuous heterophyly, leaves of side rosettes and some outer leaves often undivided, up to 2 cm wide, variably dentate to sinuate-lobulate, the other leaves pinnatipartite to pinnatisect; lateral segments ± patent to slightly subrecurved, in 4–6 pairs, triangular-deltoid, or with a broad triangular basal half and an elongated, linear to linear-lingulate distal part, distal margin usually ± concave, entire or with 1–2 (or several minute) teeth, proximal margin usually straight, entire, apex acute to subacute; terminal segment small, flat-triangular to ± tripartite, entire, apex acute, basal lobules small, patent, acute; interlobes short, usually ca. 5 mm wide, rarely entire, usually with 1–2 teeth; mid-vein green or suffused brownish-purplish. Scapes growing from outside the leaf rosette, ± arachnoid (but almost glabrous just below capitulum), ± brownish green, equalling or slightly overtopping leaves. Capitulum golden yellow, ca. 3.5–4.5 cm wide. Involucre dark (blackish) olivaceous-green, not pruinose, ca. 10–11 mm wide and rounded to broadly subobconical at base. Outer phyllaries usually 11–14, appressed, ± not imbricate (the outermost ones long, ± equalling the others, all reaching ca. 2/3 of the inner phyllaries), seldom ovate, usually ovate lanceolate, some of them lanceolate, usually (7–) 8–9 (–9.5) × (2.8–) 3.2–3.7 mm, abaxial surface with middle part dark blackish olivaceous (± black when dry), with a subabrupt transition into a pale border ca. 0.8–1.0 mm wide, pale border divided in the inner pale greenish part, with a gradual transition into a variably broad membranous border, distal part of phyllaries usually suffused dark purplish, margin initially long ciliate, later very sparsely ciliate, apex (at least in later capitula) with a thick blackish horn 0.3–1.0 mm long. Outer ligules flat, striped light grey outside, teeth grey, inner ligule teeth grey-yellow. Stigmas light greyish yellow (dirty yellow with sparse, mixed hyaline and grey pubescence outside). Pollen present, irregular in size. Achenes light greyish stramineous-brown, ± slender, ca. 4.4–4.7 × 0.8–1.0 mm, body with subsparse, medium long to short, erect-patent (rarely subpatent) acute squamules, very gradually narrowing into a subcylindrical cone usually 0.7–0.9 mm long (difficult to measure because of sparse short squamules ascending to lower 1/3–1/2 of the cone), beak 9–10 mm long, pappus dirty white to brownish white, ca. 6 mm long. – Agamospermous. – Fig. 86–88 .

Diagnostic notes:— Taraxacum pseudocompitale is seemingly intermediate between T. compitale and T. xanthellum . However, its outer phyllaries are distinctly, broadly bordered, distally suffused purple (and thus quite similar to those of T. tuvense (see Fig. 85 ). Another diagnostic feature of T. pseudocompitale is the shape of achenes: they are slender, very gradually narrowing into a subcylindrical cone. The size and shape of achenes also distinguish T. pseudocompitale from the other members of the core group around T. hjeltii .

Distribution and habitat:—Known from a series of gatherings from the western part of the shore of Lake Baikal.

Specimens examined:— RUSSIA. Irkutsk Region, Lake Baikal, village of Listvyanka, substeppe slopes above the port in Listvyanka , 26 Oct 1985, J. Kirschner & J. Štěpánek, cult. as JŠ 2537 ( PRA, no. det. 37780). – Less certain identification (a modification with longer cone and suberect achene spinulosity: Ibidem, cult. as JŠ 2550 ( PRA, no. det. 37782).

Figures

FIGURE 85. Taraxacum tuvense. A, general habit (LE, no. det. 6029, scale bar = 2 cm); B, a detail of an involucre from the same specimen (scale bar = 5 mm).

FIGURE 86. Taraxacum pseudocompitale. The holotype. Photo M. Hladík.

FIGURE 87. Taraxacum pseudocompitale. A, general habit of a young isotype plant; B, achenes (PRA, no. det. 37780). Scale bars: A = 2 cm, B = 1 mm.

FIGURE 88. Taraxacum pseudocompitale. General habit (one of the holotype plants, PRA, no. det. 37778).