Taraxacum zermattense Dahlstedt (1907: 19)

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

30. Taraxacum zermattense Dahlstedt (1907: 19)

Type indication:—[ SWITZERLAND] “in Helvetia ad Zermatt (Cant. Wallis) in Gornergrat loco aprico in solo subdenudato, lapidoso, subsicco regionis alpinae inf. ubi anno 1893 medio mensis Julii plantas fructiferas inveni”

Type:— SWITZERLAND. Stockh. : Bergianska trädg. odl. af fr. från Schw.: Zermatt [Stockholm, Bergian Botanical Garden, cultivated from achenes from Zermatt, Switzerland], (1) 3 May 1902, (2) May 1904 [plants on the herbarium sheet not numbered], H. Dahlstedt (S 13-8378, no. det. 9262, syntype) ; Ibidem, 25 May 1896, H. Dahlstedt (S 13-8376, no. det. 9265, syntype); 29 May 1901, 1904 (achenes), H. Dahlstedt (S 13-8329, no. det. 9229, syntype); 20 May 1900, H. Dahlstedt (S 13-8379, no. det. 9263, syntype).

Etymology:—Zermatt, a township in Canton Valais ( Wallis), Switzerland.

Exsiccates:— Taraxaca Exs., no. 1098.

Plants relatively small, usually up to 12 cm tall. Petiole narrow, unwinged, usually pale green, sometimes ± brownish green; plant base with tunic, with yellowish hairs among petiole bases. Leaves subglabrous, relatively light greyish green, narrowly oblong to narrowly oblanceolate in outline, usually 5–10 × 1.5–2.5 cm, pinnatisect, with ca. 4–6 pairs of patent or hamate-subrecurved linear-triangular or linear-deltoid lateral segments, with distal and proximal margins usually ± straight (in subrecurved segments distal margin convex, proximal concave), most often with a few little acute teeth, sometimes entire; terminal segment usually trilobed, terminal part usually ± elongated, often denticulate, basal lobules narrowly triangular, patent; interlobes usually narrow, with patent, irregular teeth and lobules; midvein usually pale greenish, sometimes proximally brownish green. Scapes distally sparsely arachnoid to arachnoid, otherwise almost glabrous, green, often suffused purplish, ± overtopping inflorescence. Capitulum ± light yellow, ca. 2.5–3 cm wide. Involucre deep olivaceous-green, 7.5–8 mm wide and broadly rounded at base. Outer phyllaries 12–15 (17), ovate, ovate-lanceolate or lanceolate, subimbricate, usually 4.3–4.8 (–6) × 2.2–2.8 mm, with middle strip dark grey-olivaceous, ca. 1 mm wide, with a gradual transition in a paler membranous-green zone 0.5–0.8 mm wide and a distinct, whitish border 0.3–0.4 mm wide, surface often later darkening, margin distally ciliate, apex usually callose to corniculate, suffused blackish olivaceous-purple; inner phyllaries ca. 10–12 mm long, flat to corniculate. Outer ligules flat, striped deep grey-purple outside, ligule teeth usually deep grey. Stigmas discoloured. Pollen absent. Achenes greyish light brown, ca. 4.0–4.5 × 0.7–0.9 mm, body ± densely, shortly spinulose in upper 1/4–1/3, ± gradually narrowing into a ± cylindrical cone 0.7–1.0 mm long; beak 6.5–7.5 mm long, pappus ± white, ca. 5 mm long. – 2n=32, fide Krahulcová (1993: 293). –Agamosperm. – Fig. 35 .

Diagnostic notes:—In its general habit, T. zermattense approaches T. aquilonare and T. ledebourii . The following combination of characters seems to be diagnostic: Achenes greyish light brown, ± densely spinulose above, pollen absent, outer phyllaries ± appressed, with a variably broad but distinct pale border, achenes relatively thin, beak shorter than 8 mm, cone cylindrical, 0.7–1 mm long.

Distribution and habitat:— Taraxacum zermattense is known to occur in Switzerland and France, in relatively dry sites of inner Alpine valleys, usually on limestone rocky and gravelly slopes with shallow soils, most often between 1800 and 2500 m.

Selected specimens examined:— SWITZERLAND. Wallis, Zermatt, Sunnegga, 2285 m, 26 Jul 1972, J. L. van Soest 43 (L, no. det. 21364). – Zermatt, Blauherd, 2500 m, 26 Jul 1972, V. J. van Vossen & J. L. van Soest 60 (L, no. det. 21366). – Zermatt, Tuftern, 2350 m, 26 Jul 1972, J. L. van Soest 54 (L, no. det. 24016). – Switzerland, summit area of Mt. Seehorn, near Simplon Ridge, 2450 m, 29 Jul 1906, H. Handel-Mazzetti (W, no. det. 20854; WU, no. det. 21868). – Graubünden, Lukmanier Pass, S side, 18 Jul 1984, W. Trepp (ZT, no. det. 24934). – Wallis, Zermatt, Berghaus Trift, 2320 m, 6 Jul 1987, E. Albertshofer (PRA, no. det. 33590).

Figures

FIGURE 35. Taraxacum zermattense. A, general habit (ZT, no. det. 24934); B, C, D, details of capitulum (all S, no. det. 9263). Scale bars: A = 1 cm; B, C, D = 5 mm.