Taraxacum subcompactum Kirschner & Štěpánek, 2023

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

22. Taraxacum subcompactum Kirschner & Štěpánek , sp. nov.

Type:—[ RUSSIA, Respublika Altay] Sibiria austro-occid., montes Altaj, distr. Usť-Ulagan, in locis siccis ad viam publicam haud procul a pago Aktaš , 2 Jul 1988, J. Kirschner, cultivated as JŠ 3367 ( PRA, no. det. 35842, holotype; isotype: PRA, no. det. 36688) .

Etymology:—Similar to T. compactum , or “almost compact”.

Exsiccates:— Taraxaca Exs., no. 1368.

Diagnosis:—Species in sectione Dissectorum marginalis, petiolis alatis vel late alatis, foliis arachnoideis, vena mediana brunneo-purpurea, phyllariis involucralibus exterioribus adpressis, plerumque ovatis, late scarioso-marginatis, acheniis brevibus cinnamomeis vel stramineo-brunneis rubescentibus, pyramide subconica et rostro ad 6.5 mm longo bene dignoscendae.

Plants small, rarely to medium-sized, usually 8–12 cm tall. Petioles narrowly winged to ± broadly winged, the innermost ones unwinged, often suffused brownish-purplish, arachnoid; plant base with dense whitish hairs, tunic ± developed. Leaves mid-green to reddish mid-green, arachnoid or sparsely arachnoid, linear-oblanceolate in outline, usually 5– 10 × 1–2.5 cm, pinnatilobed to pinnatipartite, sometimes pinnatisect or undivided, usually with 3–5 pairs of patent, triangular-deltoid to triangular lateral segments, distal margin usually subconcave, less often ± straight or subsigmoid, entire or with a single tooth, proximal margin usually straight, entire, often ± pointing forwards; terminal segment smaller, ± triangular or deltoid, distal margin subconvex to straight, often with 1–2 pairs of symmetrical incisions or small triangular teeth; interlobes short, broad, entire or with 1–2 little teeth; mid-vein often suffused brownishpurplish, sometimes green; usually some outer leaves undivided and densely irregularly dentate, similar to leaves developed after anthesis. Capitulum yellow, ca. 2.5 cm wide. Involucre grey-green, 0.9–1.0 cm wide and rounded at base. Outer phyllaries usually 12–15, appressed, subimbricate, broadly ovate to ovate-lanceolate, usually (5.5–) 6.5–8 (–9) × 2.3–3.6 mm, surface greyish olivaceous-green, deep mid-green or light green, border clearly visible, whitish-membranous, not sharply delimited, 0.4–0.7 (–0.9) mm wide, margin ciliate, apex callose to corniculate; inner phyllaries usually 12–14 mm long, flat to callose. Outer ligules flat, striped dark grey to grey-pink outside, inner ligule teeth dirty purplish. Stigmas light yellowish green. Pollen present, irregular in size. Achenes cinnamon or light reddish stramineous brown, ± robust, ca. 3.2–3.4 × 0.8–0.9 mm, body ± densely spinulose in upper 1/3 (spinules distinct, erectpatent, long), subabruptly narrowing into a thicker, subconical cone 0.6–0.7 mm long, 0.35 mm thick at base, ca. 0.3 mm distally; beak 6.5 mm long, pappus 5 mm long, ± yellowish. – Agamosperm. – Fig. 24 , 25 .

Diagnostic notes:—The arachnoid leaves with winged petioles, the broadly bordered ± ovate outer phyllaries, and the cinnamon achenes with a subconical cone are diagnostic. This taxon may be superficially similar to T. compactum , see also notes under the latter name. Taraxacum subcompactum is in many respects similar to T. ceratosectum ; its achene size and colour, cone shape and length, the character of achene spinulosity, beak length and petiole width are diagnostic. Taraxacum subcompactum may be considered as a marginal species of T. sect. Dissecta , with some features of T. sect. Borealia .

Distributon and ecology:— Taraxacum subcompactum is known from two districts of the Altai Republic (Ongudai and Ulagan Districts) and from the city of Irkutsk. It grows on dry, steppe to semisteppe sites, at ca. (450–) 1000–1800 m a.s.l.

Specimens examined:—[ RUSSIA, Respublika Altay] Altai Mts., Usť-Ulagan District, dry sites along the road in the vicinity of Aktash village , ca. 1800 m, 2 Jul 1988, J. Kirschner, cultivated as JŠ 3367 ( PRA, no. det. 36688, with duplicates) . – Altai Mts., Ongudai District, Khabarovka, between the road and the river Malyy Iľgumeň [ca. 50° 41’ N, 86° 17’ E], 29–30 jun 1988, J. Kirschner, cultivated as JŠ 3337 ( PRA, no. det. 36790) . – Irkutsk, dry grasslands between the Ushakovka River and the monastery in the periphery of the city, ca. 450 m, 25 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2695 ( PRA, no. det. 36952) .

Figures

FIGURE 24. Taraxacum subcompactum. A, General habit (a scan of plants from the holotype gathering, PRA); B, Achenes (PRA, JŠ 3337).

FIGURE 25. Taraxacum subcompactum. A SEM picture of an achene from the cultivation JŠ 3337. Scale bar = 1 mm.