Taraxacum subtrigonum 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 : 91-94

36. Taraxacum subtrigonum Kirschner & Štěpánek , sp. nov.

Type:—[ RUSSIA, Kamchatka] Kamchatskiy kray, Bystrinskiy raion, Bystrinskiy prirodnyy park, severo-zapadnaya chast’ parka, 56°28.548’ N, 157°55.945’ E, nizkotravnyy sklon SV ekspozicii [Kamchatka, NW. part of the Bystrinskiy Nature Park, a short-grass NE. slope], 1088 m, 26 Jul 2014, V. V. Buryy (herb. V. V. Buryy, no. det. 36858, holotype) .

Etymology:—With leaf segments of a nearly triangular shape.

Diagnosis:— Affinis Taraxaci trigonolobi sed differt statura gracilior, forma foliorum plus complicata, petiolis angustis, phyllariis exterioribus subimbricatis vel non imbricatis, angustissime marginatis, acheniis longioribus et pyramide subcylindrica, etiam scapis glabrescentibus vel sparsissime arachnoideis.

Plants small to medium-sized, of a relatively slender growth, usually 12–15 (–20) cm tall. Petiole light green, narrow and unwinged or narrowly winged in middle and later leaves, winged in the earliest leaves, often missing or decaying during flowering, glabrous, plant base without indumentum or tunic. Leaves light vivid green, glabrous, ± oblanceolate, usually 6–11 (–15) × 1.5–2.5 (–3.0) cm, usually pinnatifid to pinnatisect, with 2–3 (4) pairs of patent to subrecurved, deltoid-triangular to narrowly triangular lateral segments, distal margin ± convex and entire in earlier leaves, sigmoid or ± straight, entire or very sparsely denticulate in later middle leaves, proximal margin ± straight, entire, in later leaves often with a single tooth, apical part often elongated, acute to lingulate; terminal segment flat triangular or triangular-hastate; interlobes entire or with sparse short teeth; mid-vein usually suffused purplish, at least distally. Scapes brownish green, usually suffused purplish distally, subglabrous or with sparse arachnoid hairs, not more densely hairy below capitulum, overtopping leaves. Capitulum yellow, 3–4 cm wide. Involucre deep grey-green or black-green, sometimes ± pruinose, mostly not so, 7–8 mm wide and rounded at base. Outer phyllaries 11–14, appressed, subimbricate to ± not imbricate, (the lowermost ones) broadly ovate to (upper) ovate-lanceolate, usually (4–) 5–6 (–8) × 2.5–4 mm, surface ± evenly black-green, rarely olivaceous-green, paler border often not developed, sometimes membranous or whitish membranous, very narrow, usually 0.1–0.2 mm, rarely to 0.3 mm wide, margin sparsely ciliate, apex darker, flat or corniculate; inner phyllaries blackish olivaceous-green, flat or minutely corniculate. Outer ligules flat, striped grey or pinkish grey outside, sometimes faintly so, teeth blackish. Stigmas dark discoloured, almost black when dry. Pollen sparsely present, pollen grains irregular in size. Achenes light greyish stramineous-brown, 4.9–5.2 × ca. 1 mm, body with subdense short spinules and squamules in upper 1/3, subgradually narrowing in a subcylindrical cone 0.9–1.2 mm long, usually ca. 0.4 mm thick at base, ca. 0.3 mm distally; beak thin, ca. 9 mm long, pappus white, 6.5–7.5 mm long. – Agamospermous. – Fig. 60–62 .

Diagnostic notes:— Taraxacum subtrigonum is very close to T. ceratophorum s. str. (= T. trigonolobum ) but can be distinguished by scapes glabrous or very sparsely arachnoid (not densely arachnoid below capitulum), petioles of middle leaves narrow, unwinged, the ± slender growth (not robust as in T. ceratophorum s. str.), outer phyllaries unbordered or very narrowly bordered, subimbricate or ± not imbricate, and achenes longer, with a longer, subcylindrical cone.

Distribution:—According to the material available, T. subtrigonum seems to be relatively common in Central Kamchatka, in the Bystrinskiy and Mil’kovskiy Districts. It prefers tundra sites and various habitats along brooks, usually from 800 to 1200 m a.s.l.

Specimens examined:—[ RUSSIA, Kamchatka] Bystrinskiy District, Bol’shoe Gol’tsovoe Lake, 56°28.251’ N, 157°57.065’ E, 867 m, a meadow near the lake, 24 Jul 1914, V. V. Buryy (herb. V. V. Buryy , no. det. 36847). – Kamchatskiy Kray , Bystrinskiy District , upper stream of the Tupikin Klyuch , along an unnamed drying-up brook, 55.90497° N, 158.78506° E, 1012 m, 23 Aug 2012, V. V. Buryy (herb. V. V. Buryy , no. det. 36849). – Kamchatskiy Kray , Bystrinskiy District , Bystrinskiy Nature Park, NW. part of the Park , 56°28.461’ N, 157°56.497’ E, 987 m, 25 Jul 2014, V. V. Buryy (herb. V. V. Buryy , no. det. 36851). – Kamchatskiy Kray , Bystrinskiy District , Opal’ka River , ca. 1.5 km E of 56°16.958’ N, 159°20.291’ E, ca. 1000 m, stony tundra, 30 Jul 2014, A. Lace (herb. V. V. Buryy , no. det. 36857). – Central Kamchatka, Mil’kovskiy District , Nikolka , ca. 1260 m, tundra slope near rocks, 20 Aug 1987, V. V. Yakubov ( KAM, no. det. 36859). – Bystrinskiy District , SW. of Ichinskaya Sopka volcano, near R. Galdavit , 55°46.467’ N, 157°45.368’ E, 1223 m, 31 Jul 2015, V. V. Buryy T076 (herb. V. V. Buryy, no. det. 36911). – Bystrinskiy District , Kozyrevskiy Khrebet range, vicinity of the village of Esso, 55°54.247’N, 158°47.467’E, 1095 m, 16 Aug 2015, V. V. Buryy T072 , T073 (herb. V. V. Buryy, no. det. 36913, 36914). – Bystrinskiy District , Kozyrevskiy Khrebet range, vicinity of Esso, mountain tundra, 55°55.090’N, 158°48.207’E, 1420 m, 28 Jul 2022, V. V. Buryy T003 (herb. V. V. Buryy, no. det. 36918). – Less certain identification:— Kamchatka, Bystrinskiy District , Bystrinskiy Nature Park, NW. part of the Park, Bol’shoe Gol’tsovoe Lake , 56°27.634’ N, 157°57.138’ E, 858 m, 26 Jul 2014, V. V. Buryy (herb. V. V. Buryy, no. det. 36850). – Kamchatskiy Kray, Bystrinskiy District , Sredinnyy Khrebet, sources of the Pravaya Nachiki River , zone of tundra, shore of a drying-up lake, 56°08.818’ N, 159°06.736’ E, 1196 m, 15 Aug 2014, K. G. Klimova ( KAM, no. det. 36853). – Bystrinskiy District , SW. of Ichinskaya Sopka volcano, Mt. Dva Brata , 55°35.369’ N, 157°29.603’ E, 1375 m, 8 Aug 2017, V. V. Buryy T051 (herb. V. V. Buryy, no. det. 36916). – Kamchatka, Bystrinskiy District , Bystrinskiy Nature Park, NW. part of the Park, 56°25.510’ N, 157°42.527’ E, turf among stones near a brook, 747 m, 18 Jul 2014, V. V. Buryy (herb. V. V. Buryy, no. det. 36848). – Bystrinskiy District , W. of Ichinskaya Sopka volcano, lake shore, 55°36.547’N, 157°34.220’E, 1163 m, 4 Aug 2015, V. V. Buryy T003 (herb. V. V. Buryy, no. det. 36931) .

Species with achenes light fulvous, red, red-brown or reddish brown

Figures

FIGURE 60. Taraxacum subtrigonum. General habit (A, KAM, no. det. 36858, a plant from the holotype sheet; B, KAM, no. det. 36847). Scale bar = 2 cm.

FIGURE 61. Taraxacum subtrigonum. A, slightly unripe achenes (KAM, no. det. 36858), scale bar = 1 mm; B, a detail of capitulum (photo V. V. Buryy, 31 Jul 2015, Ichinskaya Sopka region).

FIGURE 62. Taraxacum subtrigonum. The holotype. Photo M. Hladík.