Taraxacum calens 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 : 43-44

13. Taraxacum calens Kirschner & Štěpánek , sp. nov.

Type:— KAZAKHSTAN. East Kazakhstan, Altai Mts. , alpine grasslands near timberline, W of the valley of “Kurta” brook, ca. 17.5 km SSE of the village of Arshaty , ca. 1950 m, 49.1513°N, 86.6847°E, 7 Jul 2006, P . Koutecký , cultivated as JŠ 8184, collected in 2008 ( PRA, no. det. 37800, holotype; numerous isotypes in PRA) .

Etymology:—Derived from caleo, to burn, to flame.

Diagnosis:—Plantae heterophyllae, foliis saturate obscure viridibus, interlobiis conspicue maculatis, petiolis late alatis, phyllariis exterioribus atro-cornutis, membranaceo-marginatis, acheniis breviter squamulosis crassis, corpore in pyramidem conicam subabrupte abeunte, rostro longissimo, pappo brevi notabiles.

Plants medium sized, of subrobust appearance and a compact growth, usually 7–14 cm tall. Plant base without tunic, sparsely arachnoid among petiole bases; petioles winged to broadly winged, often suffused purplish along mid-vein. Leaves with a conspicuous heterophyly, ± dark green, initially arachnoid, later sparsely arachnoid at least along mid-vein, outer and middle leaves (those with well developed interlobes) conspicuously blotched brown-purple, oblong-lanceolate in outline (often distally narrower than in the middle), 6–12 × (1–) 2–2.5 (–3.5) cm, outer and most of middle leaves pinnatilobed to pinnatipartite, with 5–7 pairs of ± patent, deltoid lateral segments, distal margin usually straight to subconcave, entire or with 1–2 teeth, proximal margin ± straight, entire, apex acute to acuminate; terminal segment small, trilobed to tripartite, lobes acute, margin entire; interlobes broad, conspicuously irregularly blotched deep brown-purple, entire or with a few minute teeth; mid-vein usually slightly suffused brown-purple; inner leaves or leaves of side rosettes dentate or lobulate, lobules usually subrecurved, acute, surface not spotted. Scapes often growing outside the main rosette, arachnoid, brownish green or suffused bronze, subequalling leaves. Capitulum yellow, usually 3–4 cm wide. Involucre usually blackish green, 9–12 mm wide and broadly rounded at base. Outer phyllaries 10–14, reaching ca. 2/3 of the inner, usually erect, some subappressed, some erect-patent, ± lanceolate, usually 9.0–10.5 × 2.8–4.2 mm, surface dark (blackish) olivaceous-green, with an almost black middle strip ca. 0.5 mm wide, bordered olivaceous, with a gradual transition into a membranous border 0.2–0.6 mm wide, margin ± not ciliate, apex dark, with a thick or thin horn usually 1–2 mm long; inner phyllaries of ± invariable width, 14–15 mm long, corniculate. Outer ligules flat, striped light grey to grey-olivaceous outside, teeth greyish, inner ligule teeth dirty yellow. Stigmas greenish, with a darker pubescence outside. Pollen present, pollen grains irregular in size. Achenes light greyish stramineous-brown, usually (3.8–) 4.1–4.5 × (1.0–) 1.1–1.4 (–1.5) mm, body subsparsely to subdensely covered with short, sometimes subrobust squamules in upper 1/3, with a subabrupt transition into a subconical to conical cone 0.4–0.7 mm long, usually 0.5–0.6 mm thick at base, ca. 0.45–0.5 mm distally, beak thin, (10–) 12–14 mm long, pappus ± white, ca. 5.5 mm long. – Agamospermous. – Fig. 25 , 26 .

Diagnostic notes:— Taraxacum calens is geographically and morphologically close to T. pingue , particularly in having similar outer phyllaries and achenes. The comparison is difficult because the latter name is based on rather scanty material with imperfectly ripe achenes. However, T. calens has less numerous, erect outer phyllaries, less dark stigmas, a shorter cone, a very long beak and a shorter pappus. We should mention a very different leaf shape, but the scanty material of T. pingue does not suffice to consider this feature as fully reliable. The conspicuous difference in flower colour (whitish in T. pingue ) may be important, provided that it is confirmed by new collections in the Saur Mts.

Distribution and habitat:—It is known from a series of gatherings in the Kazakhstan part of the Altai Mts., growing there around 2000 m in subalpine meadows.

Specimens examined:— KAZAKHSTAN. East Kazakhstan, Altai Mts., alpine grasslands near timberline, W of the valley of “Kurta” brook, ca. 17.5 km SSE of the village of Arshaty , ca. 1950 m, 49.1513°N, 86.6847°E, 7 Jul 2006, P. Koutecký, cult. as JŠ 8186 ( PRA, no. det. 37804). – Ibidem, cult. as JŠ 8202 ( PRA, no. det. 37802). – Ibidem, cult. as JŠ 8185 ( PRA, no. det. 37806) .

Figures

FIGURE 25. Taraxacum calens. The holotype. Photo M. Hladík.

FIGURE 26. Taraxacum calens. A, general habit; B, achenes (both PRA, no. det. 37800, holotype). Scale bars:A = 2 cm, B = 1 mm.