Taraxacum longicorne Dahlstedt (1906: 9)

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 : 116-117

49. Taraxacum longicorne Dahlstedt (1906: 9) Type:—[ RUSSIA, Sakha Republic] Ytyk-Chaja [Ytyk-khayya], 15 Jul 1901, A. K. Cajander (H, syntype, n. v., fide Hämet-Ahti 1970:

320). – Lena, Bulun, 5 Jul 1898, N. H . Nilsson 54 ( S 13-4415 !, syntype; S 13-4414 !, syntype). – “ad fluvios Olenek et Lenam inf. et inter Olenek et Lenam”, 1875, Czekanowski ( UPS, syntype, n. v.; LE, isosyntypes!). Etymology:—With long horns .

Plants medium-sized, ± robust, ca. 15–20 cm tall. Petioles broadly winged, ± purplish, glabrous. Leaves ± mid-green, glabrous, narrowly oblanceolate in outline, usually 6–12 (–17) × 1.2–2.0 (–2.5) cm, mostly undivided, with 1–3 pairs of remote, patent lobules, inner leaves often pinnatifid, with 3–4 (5) pairs of patent or subrecurved, ± triangular to deltoid-triangular, entire or denticulate lateral segments; terminal segment triangular, with patent basal lobules. Scapes brownish green, sparsely arachnoid distally, overtopping or ± equalling leaves. Capitulum yellow, ca. 4 cm wide. Involucre dark greyish olivaceous-green, ca. 8–9 mm wide and rounded at base. Outer phyllaries not numerous, ca. 10–12, appressed, subimbricate, ovate (often acuminate from a broadly ovate base) to ovate-lanceolate or ± lanceolate, 6–7 (–8) × 2.5–3.0 mm, middle part dark greyish olivaceous-green, with a ± abrupt transition into a distinct, whitish (distally suffused pink) border usually 0.6–1.0 mm wide, margin sparsely ciliate distally, apex with a very conspicuous, usually perpendicular horn ca. 2–3 mm long; inner phyllaries dark greyish olivaceous-green, 14–16 mm long, often coalescing. Outer ligules narrow, ± canaliculate, striped grey outside, teeth greyish. Stigmas light discoloured. Pollen present. Slightly unripe achenes light greyish stramineous-brown, ca. 4.5 mm long, cone subconical, ca. 0.8 mm long; beak 8–10 mm long, pappus ± white, ca. 5.5 mm long. – Fig. 80 .

Diagnostic notes:—Although fully ripe achenes are not available for comparison, there are several diagnostic features characterizing T. longicorne : not numerous, ovate to lanceolate, broadly and conspicuously whitish bordered outer phyllaries with very long horns, and leaves usually undivided, lobulate. The differences from T. hultenii are summarized above. The group of species around T. hjeltii and T. macroceras , in addition to the yellow stigmas, differs in the much narrower and very narrowly bordered outer phyllaries.

Distribution:—Known from the lower Lena River, Sakha Republic, and from Taimyr Peninsula.

Specimens examined:—[ RUSSIA] Siberia , Taymyr Peninsula , western shore of Lake Sobach’e , near the mouth of Nakhta River , gravelly shore, 69°03’8.25”N, 90°58’25.8”E, 51 m, 12 Jul 2018, I. N. Pospelov 18-0957 ( NSK, photo!). – Southeastern Taymyr , Khatanga River, Dzhon-Ary Island, 72°18’16.4”N, 103°10’52.2”E, 8 Aug 2014, I. N. Pospelov 14-0271 ( NSK, photo!) .

Figures

FIGURE 80. Taraxacum longicorne. Details of involucre. A, S 13-4415 (scale bar = 10 mm); B, S 13-4414 (scale bars: B, C, D = 5 mm).