Taraxacum leptoceras Dahlstedt (1926b: 5)

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 : 53-54

18. Taraxacum leptoceras Dahlstedt (1926b: 5)

Type:—[ RUSSIA] Kamchatka, Petropavlovsk [Petropavlovsk-Kamchatskiy], 1 Jun 1921, E. Hultén ( S 12-27582 !, syntype) . – V. Komarov, Iter Kamczaticum I., verkhnee ozero Petropavlovskogo ot. [upper Petropavlovsk Lake], 31 May 1908 [13 Jun 1908, modern calendar] V. P. Savich 15 ( LE, no. det. 6083, syntype) . – Kamchatka, g. Petropavlovsk [Petropavlovsk-Kamchatskiy], koshka verkhnego ozera, 31 May 1908 [13 Jun 1908, modern calendar] V. P. Savich ( LE!, isosyntype) . – Kamchatka, Avachinskaya guba, na peschano-galechnoi kos’e otdelyayushchei Verkhnee ozero Petropavlovska ot morya [on the sandy-gravelly spit dividing the Upper Petropavlovsk Lake from the sea], V. Komarov , Iter Kamczaticum I., 31 May 1908 [13 Jun 1908, modern calendar] V. P. Savich ( MW, no. det. 20475, isosyntype) .

Etymology:—From Greek words, leptós – thin, slender, and latinized Greek word kéras, horn.

Note:—We have examined the whole original material of the name T. leptoceras , and also studied an additional, very well developed authentic specimen ( Dahlstedt 1930, collected by R. Malaise in 1928). The main problem is that achenes are lacking from the above material, and it is therefore difficult to equate our material with the authentic specimens without doubts. The OM, moreover, may be heterogeneous. Our plants are extremely close to the R. Malaise gathering, and we therefore include them in T. leptoceras sensu lato. The description is compiled on the basis of our gatherings, taking the authentic specimens into account.

Plants medium-sized, 10–15 cm tall. Petiole deep purple, ± sparsely arachnoid, narrowly winged to ± unwinged, tunic absent. Leaves dark green, usually with dirty pinkish mid-vein, usually dark blotched and irregularly spotted on interlobes, ± oblanceolate in outline, usually 6–11 × 1.5–4.0 cm; terminal segment usually ± tripartite to trilobed, with distal part acute, narrowly triangular to lingulate, basal lobules ± patent, acuminate, narrowly triangular, distal margin concave, ± entire or with a single tooth (in the innermost leaves, terminal segment triangular, acute, often with asymmetrical incisions), proximal margin ± straight, entire; lateral segments in 3–5 pairs, usually patent, seldom subrecurved or pointing forward, linear-triangular to narrowly triangular, frequently narrowing from a broad base into a sublinear, acuminate distal part, distal margin subconcave or sigmoid, entire or with 1–2 perpedicular filiform teeth, proximal margin ± straight, entire; interlobes long, distinct, usually 2–7 × 2–3 mm, usually with sparse thin teeth, surface adaxially blotched dark brown-purple, often also with irregular elongated spots; inner leaves generally more conspicuously filiform dentate and lobulate. Scapes arachnoid to subglabrous, brownish green, usually ± equalling leaves. Capitulum yellow, 3–4 cm wide. Involucre dark or blackish olivaceous-green, 8–10 mm wide and ± rounded at base. Outer phyllaries 12–16, erect, erect-patent to arcuate-patent, linear-lanceolate to narrowly lanceolate, usually 8–10 × 2–3 mm, surface usually evenly dark olivaceous-green, but not rarely with a pale greenish border zone in proximal part of phyllary, otherwise border almost invisible, membranous, ca. 0.1 mm wide, margin sparsely ciliate distally, apex usually with a blackish cornicle or a short horn to ca. 1 mm long. Inner phyllaries dark olivaceous-green, usually 12–14 mm long, not coalescing, apex usually corniculate. Outer ligules flat, striped ± grey outside, teeth grey-yellow, inner ligule teeth yellow to dirty yellow. Stigmas ± light greenish with dark pubescence outside. Pollen present, pollen grains irregular in size. Achenes light greyish stramineous-brown (more greyish than in other taxa of this group), ca. 3.6–4.0 (–4.3) × 0.8–0.9 (–1.0) mm, body ± densely spinulose in upper 1/3, ± subabruptly narrowing into a cylindrical to subcylindrical cone 0.5–0.7 (–0.9) × 0.25–0.30 mm; beak ca. 9 mm long, pappus white, ca. 5.5 mm long. – Agamospermous. – Fig. 3F , 33 .

Diagnostic notes:— Taraxacum leptoceras is relatively close to T. perdecorum as they share most of the characters of outer phyllaries. The former is readily distinguished by a longer, subcylindrical cone, different leaf shape and colour (darker leaf blade colour, with spotted to blotched interlobes), and darker stigmas. Another similar taxon is T. acricorne . The latter has ± loosely appressed outer phyllaries with a paler border 0.3–0.4 mm wide, and its leaves are not so deep green and lack brown-purple spots. Both from T. perdecorum and from T. peracre , T. leptoceras can be distinguished on the basis of achene characters. The ± cylindrical, longer cone and a subabrupt cone/body transition are diagnostic. However, the heterogeneous or otherwise inadequate original material and the lack of achenes in it make it difficult to evaluate the whole material in a responsible way.

Distribution:— Taraxacum leptoceras was collected in the City of Novosibirsk, in the vicinity of Petropavlosk Kamchtskiy, and at two alluvial sandy sites in the Altai.

Specimens examined:— RUSSIA. Central Siberia, city of Novosibirsk, quarter of Akademgorodok, lawns in the vicinity of “Dom Uchonykh” hotel [Дом ученых], 21 Jun 1988, J. Kirschner, cultivated as T 83 ( PRA, no. det. 35988, 36725). – Southern Kamchatka, Savoiko, 12 Jun 1928, R. Malaise ( S 10-39688 !). – Gorno-Altaisk , Shebalino District , along the river Sema in the vicinity of Cherga , 24–25 Jun 1988, J. Kirschner , cultivated as JŠ 3321 ( PRA, no. det. 36729). – Shebalino District , sandy shores of Katun River near Usť-Sema village , 26 Jun 1988, J. Kirschner, cultivated as JŠ 3323 ( PRA, no. det. 36727) .

Figures

FIGURE 3. Details of involucres of Taraxacum species from the Altai, in alphabetic order. A, T. abhorrens (PRA, JŠ 2703); B, T. candicans (PRA, no. det. 35860); C, T. compitale (PRA, no. det. 35857); D, T. crassicarpum (PRA, no. det. 35858); E, T. sublateritium (PRA, no. det. 35859); F, T. leptoceras (PRA, T 83); G, T. mimosiflorum (PRA, no. det. 35853). Scale bars: A, E = 2 mm; B, C, D, F, G = 5 mm.

FIGURE 33. Taraxacum leptoceras. A, general habit (PRA, no. det. 35988); B, achenes (PRA, JŠ 3323/84); C, capitulum (R. Malaise, S 10-39688).