Taraxacum jacuticum Tzvelev
Creators: name: Kirschner, Jan
name: Štěpánek, Jan
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Asterales
Asteraceae
Taraxacum
Taraxacum jacuticum

description: 28. Taraxacum jacuticum Tzvelev in Tzvelev & Jurtzev (1984: 195)   
 Type:—[RUSSIA, Sakha Republic] Jakutia, Yanskiy raion, dolina reki Sartang, u pos. Bala, zlakovo-osochkovaya step [district of Jana, Sartang River valley, near the village of Bala, a grass-sedge steppe], 29 Jun 1965, V. I. Perfil’eva (LE, no. det. 6050, holotype).   
 Etymology:—After Yakutia, the Sakha Republic.   
Plants small, usually 6–10 cm tall, later to 15 cm tall. Plant base with a slightly developed tunic, arachnoid among petiole bases. Petiole very narrow, unwinged, purple. Leaves subglabrous, slightly greyish green, outer and middle leaves 4.5–6 × 1–1.5 cm, oblanceolate, pinnatilobed to pinnatisect, terminal segment triangular to helmet shaped, usually ca. 1 × 0.8–1.0 cm, usually subobtuse, lateral segments in 2–3 pairs, narrowly lingulate-triangular, subrecurved, not very acute, ± entire or with sparse basal teeth, interlobes entire; inner leaves (prevailing in the type plants) up to 10 × 2 cm, with terminal segment elongated, acute to acuminate, 1.5–2 × ca. 1.0– 1.3 cm, basal lobules patent, acute, lateral segments 3–4 patent to subrecurved, acute, ± entire, interlobes entire. Scape green to purplish green, sparsely arachnoid, ± overtopping leaves. Capitulum yellow or pale yellow, ca. 2.5 cm wide. Involucre ca. 8 mm wide and rounded at base. Outer phyllaries ca. 11–13, slightly imbricate, appressed, ovate-lanceolate to lanceolate, 4.5–5.5 × 2–2.5 mm, not exceeding 1/2 of the inner phyllaries, surface light green to pale green, border well developed, whitish, 0.20–0.25 mm wide, margin ciliate, apex darker coloured, blackish corniculate; inner phyllaries 12–13 mm long, ± corniculate. Outer ligules probably flat, striped black-purple outside. Stigmas light greenish, with a dark pubescence outside. Pollen present, pollen grains irregular in size. Achenes deep red-brown, 3.2–3.5 × 0.6–0.75 mm, body subsparsely covered with broad short subpatent to erect-patent spinules and short squamules, gradually narrowing into a thin cylindrical cone 0.6–0.7 × 0.2–0.25 mm; beak 5.5–6.5 mm long, pappus yellowish white, ca. 5 mm long. – Agamosperm. – Fig. 31.  
 Note:—There is a paratype material that, in part, may be conspecific with T. jacuticum. On a specimen from the Indigirka River basin, P. G. Zhukova determined the chromosome number (2n=32).   
 Diagnostic notes:—According to the outer phyllaries, and partly also achenes, T. jacuticum belongs to T. sect. Dissecta; as an alternative, T. sect. Erythrosperma may be considered. It is characterized by small, slender achenes with a thin cylindrical cone, pale green outer phyllaries with a well visible whitish border ca. 0.2 mm wide and an apex with a dark corniculation, and discoloured stigmas. It is most similar to T. divulgatum (for differences, see the key to the identification of Dissecta species). Taraxacum jacuticum is accepted here rather tentatively because of a rather scanty material available.   
 Distribution and habitat:— Taraxacum jacuticum is known to occur in the northern region of the Sakha Republic near the Arctic Circle, in the basins of the rivers Yana, Indigirka and Kolyma, in the coldest territory in the world (Tzvelev & Yurtzev 1984). In the Sartang River site, it grows in steppe-tundra patches (Chytrý et al. 2019) with a common sedge, Carex duriuscula Meyer (1831: 214), on the elevated places of the floodplain, otherwise dominated by moist tundra.
description: Published as part of 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, pp. 1921-1935 in Phytotaxa 590 (1) on pages 1921-1935, DOI: 10.11646/phytotaxa.590.1.1, http://zenodo.org/record/7780271