Taraxacum ovatum 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

5. Taraxacum ovatum Kirschner & Štěpánek , sp. nov.

Type:—[ RUSSIA, Irkutskaya oblast] Sibiria merid., urbs Irkutsk, locis graminosis inter fl. Ušakovka et monasterium, in peripheria urbis Irkutsk [City of Irkutsk, grasslands between the river Ushakovka and the Znamenskiy Monastery, in suburbs of Irkutsk, at 52°17’53” N, 104°17’41” E, 430 m], 25 Oct 1985, J. Kirschner & J. Štěpánek 1583/20, cultivated as JŠ 2696 ( PRA, no. det. 35839, holotype; isotype: PRA, no. det. 36682) .

Etymology:—Derived from the ovate shape of outer phyllaries.

Exsiccates:— Taraxaca Exs., no. 1376.

Diagnosis:—Differt a speciebus ceteris Sibiricis e sectione Dissectorum involucris obscure olivaceo-viridibus, basi 9–11 mm latis, phyllariis exterioribus adpressis, late ovatis usque ovato-lanceolatis, plerumque aequabiliter obscure viridibus marginibus inconspicuis membranaceis 0.4–0.8 mm latis, acheniis pallide fusco-stramineis corpore conspicue dense squamuloso, in pyramidem subcylindricam crassiusculam subabrupte transeunte.

Plants small to medium-sized, usually to 10–13 (–16) cm tall. Petiole usually narrowly winged, sometimes winged, often suffused purplish, sparsely arachnoid; plant base with whitish hairs, tunic not seen in the cultivated material. Leaves ± mid-green, sparsely arachnoid to subglabrous, narrowly oblong in outline, usually 7–11 (–16) × (2.0–) 2.5–3 (–4) cm, deeply pinnatisect, usually with (4) 5–6 (7) pairs of patent to ± recurved, triangular-deltoid to narrowly triangular lateral segments with distal margin usually sigmoid to concave, sometimes straight, usually with several little teeth or 1–2 linear lobules to the broader basal part of the segment, proximal margin straight to subconvex, usually entire; terminal segment triangular to triangular-sagittate, sometimes tripartite, with distal margin straight to concave, entire or with a single tooth; interlobes short, of variable width, usually with 1–3 lobules, or sparsely dentate, rarely entire; mid-vein frequently suffused light brownish purple. Scapes brownish green or purplish, arachnoid, subequalling inflorescence. Capitulum yellow, ca. 3.5–4 cm wide. Involucre dark olivaceous-green, 9–11 mm wide and broadly rounded at base. Outer phyllaries 10–15, appressed, ± not imbricate, broadly ovate to ovate-lanceolate, 6–9 × (2.5–) 3–4 (–5) mm, surface ± dark green, border not distinct, ± membranous, 0.4–0.8 mm wide, sometimes inconspicuously bordered by a paler zone inside, altogether to 1 mm wide, margin ciliate, apex ± flat; inner phyllaries 13–14 mm long, ± flat. Outer ligules flat, striped light grey to light pinkish grey, inner ligule teeth greyish-purplish. Stigmas yellow-green, usually with a dark pubescence outside. Pollen present, pollen grains irregular in size. Achenes light grey-stramineous, ca. 3.7–4.1 × 1.0– 1.1 mm, densely and conspicuously squamulose in upper 1/3, subabruptly narrowing into a relatively thick subcylindrical cone 0.6–0.8 (–1.0) × ca. 0.35 mm; beak 8–9 mm long, pappus ca. 5.5 mm long, ± white. – Agamosperm. – Fig. 6 .

Diagnostic notes:—A rather unusually robust plant among members of T. sect. Dissecta , it is characterized by light grey-stramineous, relatively thick achenes with a conspicuous squamulosity, numerous leaf lateral segment with distinct lobules and teeth, and the broad, ovate outer phyllaries with a relatively broad but not very distinct membranous border.

Distribution and habitat:— Taraxacum ovatum is known from a single locality in the suburbs of Irkutsk, where it grows in semiruderal grasslands, at about 430 m a.s.l.

Specimens examined:—[ RUSSIA, Irkutskaya oblast] City of Irkutsk, grasslands between the river Ushakovka and the [Znamenskiy] Monastery , in suburbs of Irkutsk [ca. 52° 17’ 53” N, 104° 17’ 41” E, 430 m a.s.l.], 25 Oct 1985, J. Kirschner & J. Štěpánek 1583/20, cultivated as JŠ 2696 ( PRA, no. det. 36682, with duplicates) .

Figures

FIGURE 6. Taraxacum ovatum. A, General habit; B, Achenes (both from PRA, no. det. 35839, holotype).