Taraxacum scalariferum 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

19. Taraxacum scalariferum Kirschner & Štěpánek , sp. nov.

Type:—[ RUSSIA, Irkutsk Region] Urbs Irkutsk, lacus Bajkal, pagus Listvjanka , in decl. stepposis supra portum in pago Listvjanka , 26 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2547 ( PRA, no. det. 35852, holotype; isotype: PRA, no. det. 36677) .

Etymology:—Bearing leaves with a shape of a ladder.

Diagnosis:—Species distincta, notis sequentibus dignoscenda, praesertim phyllariis exterioribus numerosis adpressis, plerumque anguste lanceolatis vel lanceolatis, marginibus invisibilibus, ad 0.1 mm latis, dense ciliatis, stigmatibus pallidis, acheniis brevibus necnon pyramide brevi, 0.5–0.7 mm longa.

Plants small, usually to 10 cm tall. Petiole narrow, unwinged, suffused brownish purple, usually sparsely arachnoid; plant base with ± dense whitish hairs, tunic ± developed. Leaves mid-green, not spotted nor blotched, often very narrowly bordered dark purplish, middle ones subglabrous, inner ones ± sparsely arachnoid, ± linear-oblong in outline, usually 5–8.5 × 1.2–1.9 cm, ± regularly pinnatisect, with 4–5 (6) pairs of linear, linear-triangular, or narrowly triangular, ± patent short lateral segments, with distal margin straight to concave (in segments with a dilated base), entire or with remote minute teeth, proximal margin straight, usually entire; interlobes distinct, narrow, entire or with 1 (–2) teeth; terminal segment ± tripartite, entire, basal lobules patent; mid-vein usually suffused purplish. Scape usually suffused brownish purple, arachnoid, ± overtopping leaves. Capitulum yellow, 2.5–3.5 cm wide. Involucre ± dark olivaceousgreen, usually 8–9 mm wide and broadly rounded at base. Outer phyllaries 14–17, appressed, ± not imbricate, narrowly lanceolate, lanceolate, rarely linear-lanceolate or ovate-lanceolate, 6–7.5 × 2.1–3.2 mm, surface evenly olivaceousgreen, distally darker and suffused dirty purplish, border almost invisible, membranous, to ca. 0.1 mm wide, margin densely ciliate, apex flat to ± callose. Outer ligules flat, striped faintly greyish outside, inner ligule teeth deep yellow or dirty yellow. Stigmas very light discoloured, slightly greyish yellow to almost yellow, usually almost without pubescence, or with a very short hyaline to light greyish pubescence outside. Pollen present, pollen grains irregular in size. Achenes light greyish stramineous-brown, 2.8–3.3 × 0.7–0.8 mm, body subsparsely spinulose and squamulose in upper 1/4–1/3, spinules and squamules ± short, erect-patent, body subgradually narrowing into subcylindrical cone 0.5–0.7 mm long, 0.25–0.30 mm thick at the base, 0.20–0.25 mm distally; beak 6–7 mm long, pappus yellowish white, ca. 6 mm long. – Agamosperm. – Fig. 21 .

Diagnostic notes:— Taraxacum scalariferum is in some respects quite close to T. sect. Borealia Handel-Mazzetti (1907 : xi), particularly in the general habit, the shape, number and coloration of outer phyllaries, and in achene colour. Taraxacum scalariferum has flat, not horned outer phyllaries, short achenes with a short beak, pale stigmas, and densely ciliate outer phyllaries.

Distribution and habitat:— Taraxacum scalariferum is known from a single macrolocality in the vicinity of the village of Listvyanka, near the origin of Angara R., above Lake Baikal. It grows on substeppe slopes.

Specimens examined:—[ Irkutskaya oblast] City of Irkutsk, Baikal Lake, village of Listvyanka , steppe slopes above the port in the village [ca. 51° 51’ N, 104° 52’ E, ca. 500 m a.s.l.], 26 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2547 ( PRA, no. det. 36677, with duplicates) .

Figures

FIGURE 21. Taraxacum scalariferum. A, General habit; B, Achenes (both from PRA, no. det. 35856).