Taraxacum vadosum 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

27. Taraxacum vadosum Kirschner & Štěpánek , sp. nov.

Type:—[ RUSSIA, Irkutskaya oblast] Sibiria merid., urbs Bratsk, ad ripam sinistram lacus structilis “Bratskoe More”, ca. 10 km situ a vallo, ad marg. partis centralis urbis Bratsk, haud procul a deversorio “Bratsk”, 27–28 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2575 ( PRA, no. det. 35850, holotype; isotypi: PRA, no. det. 36680) .

Etymology:—With shallows.

Diagnosis:—Species insignis foliis glaucescentibus, petiolis anguste alatis, phyllariis involucralibus exterioribus laxe adpressis usque erecto-patentibus, lanceolatis, marginibus latis sed inconspicuis, apice saepe corniculatis, acheniis pallide brunneis, pallide cinnamomeo-badiis vel pallide fulvo-brunneis, et pyramide brevi, subcylindrica.

Plants small to medium-sized, 7–13 cm tall. Petiole usually narrowly winged, green or purplish, arachnoid; plant base with dense yellowish hairs, tunic developed. Leaves greyish green to mid-green, sparsely arachnoid, narrowly oblong in outline, 6–11 × 1.5–2.8 cm, with heterophyly; some leaves undivided, dentate to sinuate-dentate, rarely some pinnatisect leaves with 4–6 pairs of dense, recurved narrowly triangular, acuminate to acute, denticulate lateral segments, most leaves pinnatisect to pinnatifid, with 3–4 pairs of ± patent or less often recurved, narrowly triangular to narrowly deltoid, distal margin straight to subconcave, sometimes sigmoid, most often with several little teeth, proximal margin usually ± straight, entire; terminal segment triangular to almost tripartite, usually ± entire, or with a deep incision, or with a single little tooth, basal lobules ± patent, sometimes subrecurved; interlobes often broad to 3–5 mm wide, entire or denticulate, often with a brown-purple patch on interlobe surface; mid-vein most often suffused purplish brown. Scapes brownish to purplish green, ± sparsely arachnoid, overtopping leaves. Capitulum yellow, 2.5–3.5 cm wide. Involucre ± olivaceous-green, usually 9–10 mm wide and broadly rounded at base. Outer phyllaries (12) 13–16 (17), loosely appressed, erect to erect-patent, not imbricate, ± lanceolate, 8–10 (–11) × (2.0–) 2.6–3.2 (–4.2) mm, border not conspicuous, ± membranous, sometimes whitish-membranous or greenish-membranous, 0.5–0.8 (– 1.0) mm wide, with a ± gradual transition into the greyish deep olivaceous-green middle part with apical part suffused pinkish, margin ciliate, apex ± corniculate to callose. Outer ligules flat, striped greyish outside, inner ligule teeth dirty yellow. Stigmas light greenish yellow to dirty yellow. Pollen present, pollen grains slightly irregular in size. Achenes light brown or light fulvous-brown to light cinnamon-brown, 3.7–4.1 × 0.8–0.9 mm, body densely spinulose in upper 1/3, subgradually to subabruptly narrowing into subcylindrical cone (0.5–) 0.6–0.8 (–0.9) × ca. 0.3 mm; beak 7–8 mm, pappus 5–6 mm, yellowish white. – Agamosperm. – Fig. 30 .

Diagnostic notes:— Taraxacum vadosum , although a member of T. sect. Dissecta , exhibits some features of T. sect. Borealia , for instance the leaf shape, and posture, shape and coloration of outer phyllaries. It is distinct in its peculiar achene colour, ± cylindrical cone shape, heterophyllous leaf shape pattern and subappressed to erect-patent, lanceolate outer phyllaries.

Distribution and habitat:— Taraxacum vadosum is known from a single macrolocality along the western shore of the Bratsk Reservoirs, growing in sparse grasslands and sandy to gravelly sites at about 400 m a.s.l.

Specimens examined:—[ RUSSIA, Irkutskaya oblast] S. Siberia, town of Bratsk , west shore of the “Bratskoe More” reservoir, about 10 km from the dam, not far from the “Bratsk” hotel, 27–28 Oct 1985, J. Kirschner & J. Štěpánek, cultivated as JŠ 2575 ( PRA, no. det. 36680, with numerous duplicates) .

Figures

FIGURE 30. Taraxacum vadosum. A, General habit; B, Achenes (both from PRA, no.det. 35850, holotype).