Taraxacum sect. Wendelboa

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Taraxacum sect. Wendelboa

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Distribution

Asia-Tropical: Pakistan native

Description

"Plants small, to 4 cm tall; plant base ± densely (whitish, yellowish to pale brownish) arachnoid, tunic usually developed. Petiole pale green, glabrous, narrow, unwinged to narrowly winged. Leaves greyish green, broadly oblanceolate in outline, usually 3–4 × ca. 0.7 cm, pinnatisect, with 1–2 pairs of deltoid-triangular, ± patent lateral segments to ca. 2.5 mm long, entire; interlobes usually 1–1.5 mm wide, to 5 mm long; terminal lobe broadly obtuse, spatulate to helmetshaped, to ca. 1 × 0.7 cm, entire. Scapes brownish green, arachnoid, densely arachnoid below capitulum. Capitulum ± paler yellow, 1 (–1.5) cm wide, to ca. 25-flowered. Involucre light green, quite narrow, 3–4 mm wide and narrowly rounded at base. Outer phyllaries 9–10, ± mid-green, ± not imbricate, ovate, the outermost ones (shorter and narrower) often narrowly lanceolate to oblong, (3–) 4.0–4.5 × (1.0–) 1.8–2.1 mm, about 1/3 as long as inner ones, ± appressed, middle part pale green to deep green, with ± abrupt transition into a whitish or whitish-membranous border 0.1–) 0.3–0.5 mm wide, surface not arachnoid, margins distally often denticulate and ciliate, apex reddish or greenish, with a dark green horn to 0.3–0.4 mm high; inner phyllaries slightly pruinose light green, glabrous, 7–8, usually ca. 9 × 2 mm, corniculate to callose below apex. Ligules lighter yellow, outer ligules ± flat, striped pinkish or greyish pink outside. Stigmas pure yellow. Anthers polliniferous, polleng grains ± irregular in size. Receptacle medium densely arachnoid, with thin flexuous arachnoid hairs to 1 mm long. Achenes light greyish stramineous-brown, of ± turbinate shape, relatively slender, 5–5.6 × 0.9–1.0 mm, body with shallow longitudinal grooves, otherwise almost wholly smooth or, in upper 1/5, with sparsely scattered minute tubercles less than 0.1 mm high, cone ± indistinguishable or inconspicuously developed, the achene part above the tuberculate part may be ± narrower, ca. 1 mm long; beak only slightly thickened, ca. 0.2 mm at base, 0.15–0.2 mm in the middle, slightly dilated below the pappus disc (ca. 0.3 mm), 1.5–2 m long; pappus white, very short, ca. 2.5 mm long, easily breaking off. Probably agamospermous."

from Kirschner & al. (2020: 145-146)A

Systematics

The monotypic Taraxacum sect. Wendelboa is unique among the genus by its arachnoid receptacle and an extremly short pappus of only c. 2.5 mm. Otherwise the only species, T. obtusum, shares all relevant features with the other members of the genus, most importantly the absence of hairs other than arachnoid ones and the occasionally present short straight simple hairs on the corolla tube, hollow scapes, taprooted rosulate habit, glabrous achenes, usually many-flowered capitula, a differentiated involucre with the outer phyllaries usually reaching at least 1/3 of the inner ones and the pappus of scabrid bristles. Therefore its former segregation from Taraxacum as an own genus Wendelboa is inappropriate in view of the low level of structural differentiation (Kirschner & al. 2020: 146-147).

Taraxacum sect. Epyramidata is the section most similar to T. sect. Wendelboa. It shares the capitula with comparatively few florets, similar involucres, relatively smooth achenes with a short, ± thickened beak and a fragile pappus. The slender, turbinate achenes of T. obtusum are not close, however, to those of the core members of T. sect. Epyramidata. The species most similar to T. obtusum is T. rubidum with almost identical involucral features and rather similar achenes, but otherwise with pinkish to lilac florets, a very different leaf shape and a much longer pappus. Another species close to T. obtusum is T. erostre with a similar leaf shape but much thicker beak, longer pappus and different involucre. (Kirschner & al. 2020: 148).A

Bibliography

A. Kirschner J., Štěpánek J., Klimeš L. & al., The Taraxacum flora of Ladakh, with notes on the adjacent regions of the West Himalaya in Phytotaxa 457: 1-409. 2020