Taraxacum amgense Kuvaev (1987: 203)

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

3. Taraxacum amgense Kuvaev (1987: 203)

Type:—[ RUSSIA, Sakha Republic] Centr. Yakutia, Megino-Ka[n]galasskiy r-n., oduvanchikovo-osokovaya step na okraine alasa Chue sprava ot trakta na Amgu 20 km za r. p. Maiya [Sakha Republic, Megino-Kangalassky District, Mayya, ca. 61° 38’ N, 130° 07’ E], 8 Jun 1960, V. Kuvaev 15-1 ( LE, no. det. 6054, holotype; isotype: MW, no. det. 20482).

Etymology:— Named after the Amga River , Central Sakha Republic.

Plants small, usually to 8–10 cm tall. Petiole narrow, usually narrowly winged, purplish, almost glabrous; plant base almost glabrous, with a well developed tunic. Leaves ± glaucous-green to greyish green, subglabrous, narrowly oblanceolate in outline, usually 3–6 (–9) × 1–2 cm, pinnatilobed to pinnatifid, lateral segments usually 2–3 (4), recurved, triangular-deltoid, ± subobtuse, distal margin subsigmoid or straight, usually entire, sometimes with a single short triangular tooth, proximal margin ± straight, entire; terminal segment usually triangular to helmet-shaped, obtuse to subobtuse, distal margin convex, usually entire, proximal margin straight, entire; interlobes broad, entire or with a single little tooth, not blotched; mid-vein suffused purple, at least proximally. Scapes usually brownish green, at least distally arachnoid, overtopping leaves. Capitulum [bright] yellow, ca. 2–3 cm wide. Involucre usually light olivaceousgreen, ca. 10 mm wide and rounded at base. Outer phyllaries not numerous, usually 10–11, appressed, not imbricate, ovate to ovate-lanceolate, usually 5–6 × 2–2.5 mm, surface olivaceous-green, distally darker and suffused purplish, border distinct, whitish-membranous, usually 0.2–0.4 mm wide, margin probably not ciliate, apex ± flat to callose. Outer ligules striped deep grey purplish outside. Stigmas yellow. Pollen absent. Achenes light red to light brownish red, ca. 3.0 [–3.5] mm long, body spinulose in upper 1/3, subgradually narrowing into a subconical cone ca. 0.4–0.5 [–1.0] mm long; beak ca. 4 mm long, pappus ca. 4 mm long, ± white. – Agamosperm. – Fig. 4 .

Note:—Along with the characters recorded on the plant material available, we occasionally also give features from the protologue (in square brackets) when they deviate from our observations or when they complete the description.

Diagnostic notes:— Taraxacum amgense is a distinctive taxon characterized by glaucous-green, usually pinnatilobed to pinnatifid leaves with a low number of lateral segments, low number of appressed outer phyllaries, yellow stigmas and absence of pollen, and small achenes with a short, subconical cone. The outer phyllary characters and the little, reddish achenes with a short subconical cone make it possible to place T. amgense in T. sect. Dissecta . However, further study is needed because of a rather limited material avauilable.

Distribution and habitat:— Taraxacum amgense is known from several sites in the Yakutsk vicinity, and grows on steppe habitats along rivers.

Specimens examined:—[ RUSSIA] Vicinity of Yakutsk , a semisteppe ... meadow in the alluvium of Lena River on the island of Khatystaakh [the centre of the town of Yakutsk], 5 Jun 1960, V. Kuvaev 8–1 ( LE, no. det. 6137) .

Figures

FIGURE 4. Taraxacum amgense. A, Achene (LE, no. det. 6054, holotype). B, C, Details of flower heads and involucre (B, MW, no. det. 20482, scale bar = 1 mm; C, LE, no. det. 6137).