Taraxacum spadiceum Kirschner & Štěpánek

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

15. Taraxacum spadiceum Kirschner & Štěpánek in Ge et al. (2011: 323)

Type:— CHINA. Xinjiang, “Tian Shan: praeruptus alveus fluminis Houxia dictus” [a canyon of Houxia River ], May 1999, P. Sekerka, D. Y. Zhan & V. Huml s.n., cultivated as JŠ 7381 ( PRA, no. det. 36148, holotype; isotype: PRA, no. det. 36150) .

Etymology:—The name is derived from the deep brown to dark castaneous-brown colour of achenes.

Plants small, 8–11 cm tall. Petiole green or purplish brown, narrow, sparsely arachnoid, plant base with tunic; leaf blade mid-green, linear-oblanceolate in outline, 3.5–8 × 0.7–1.3 cm, sparsely arachnoid, deeply pinnatisect, midvein green to pinkish and ± glabrous; lateral lobes 4 or 5 pairs, narrowly triangular to linear-triangular, ca. 5 × 2 mm, patent to subrecurved, distal margin convex or straight and entire or sparsely dentate; interlobes narrow, margin usually denticulate; terminal lobe narrowly triangular to 3-partite, margin entire. Scapes brownish or purplish green, overtopping leaves, sparsely arachnoid. Capitulum yellow, to 2.5 cm wide. Involucre 7–8 mm wide, base rounded. Outer phyllaries 10–13, subimbricate, ovate to broadly ovate, outermost ones (3–) 5–6 × 2.2–4 mm and 1/3–1/2 as long as inner ones, appressed, border distinct, narrow, whitish, ca. 0.1–0.2 mm, margin ciliate, apex ± flat; inner phyllaries 1–1.4 cm, apex blackish callose or flat. Ligules yellow; outer ligules flat, striped purplish grey outside; inner ligules with yellow or grey apical teeth. Stigmas light greyish green. Anthers without pollen. Achenes pure brown or castaneous brown, 3.2–3.8 × 0.7–0.8 mm; body subdensely spinulose in upper ca. 1/4, ± subgradually narrowing into a thin, ± cylindrical cone 0.6–0.8 mm; beak ca. 6 mm; pappus white, 4–5 mm. – Agamosperm. – Fig. 17 .

Diagnostic notes:— Taraxacum pubescens differs from T. spadiceum in fruit colour and in having broadly bordered outer phyllaries. Moreover, most of the other members of T. sect. Dissecta are polliniferous. Taraxacum (Macrocornuta) pawlodarskum from Kazakhstan has a very different leaf shape and fruit colour (see notes on the unclear taxa at the end of the text). Taraxacum obscurum has entire leaf segments and interlobes.

Distribution and habitat:—Known from the eastern Tian Shan, Xinjiang, China. Dry gravelly slopes, dry grasslands, 500–1000 m.

Figures

FIGURE 17. Taraxacum spadiceum. A, general habit (PRA, no. det. 36150). B, capitulum with involucre (PRA, no. det.36148, holotype). C, achenes (PRA, no. det. 36148, holotype). Scale bars: A = 2 cm; B = 5 mm; C = 1 mm.