Taraxacum platycranum Dahlstedt (1930: 225)

Kirschner, Jan, Štěpánek, Jan & Buryy, Vladimir V., 2025, Towards a revision of Taraxacum sect. Borealia (Compositae, Crepidinae) in Siberia and the continental Far East, with special reference to the dandelions of the Altai and Kamchatka, Phytotaxa 679 (1), pp. 1-147 : 26-30

5. Taraxacum platycranum Dahlstedt (1930: 225)

Type:—[ RUSSIA, Kamchatka] Kamtchatka, Petropavlovsk [Petropavlovsk-Kamchatskiy], in marshy tundra, 10 Jun 1928, W. Eyerdam ( S 10-40927 !, holotype; LE, no. det. 6038, isotype) .

Etymology:—Broadheaded (with a broad involucre).

Note:— The LE isotype, in addition to a standard transcribed label from the herbarium S, bears another, possibly an original Eyerdam’s field label with the date June 20, 1928 .

Plants robust, usually 15–25 cm tall. Petiole winged, ± purplish, subglabrous to sparsely arachnoid, tunic absent. Leaves ± mid-green, subglabrous, very sparsely arachnoid beneath, oblanceolate in outline, ca. (8–) 11–16 (–19) × 2.5–4.5 cm, pinnatipartite to pinnatisect, with 4–6 pairs of patent to recurved, triangular to deltoid-triangular, usually acuminate lateral segments, distal margin straight, convex or sigmoid, entire or with a few little teeth, proximal margin usually concave, entire; terminal segment broadly triangular to broadly helmet-shaped, usually entire; interlobed short; mid-vein usually purplish. Scapes brownish green, often slightly suffused purplish, sparsely arachnoid, overtopping leaves. Capitulum yellow, ca. 4 cm wide. Involucre deep olivaceous-green, 12–15 mm wide and truncate at base. Outer phyllaries ca. 12–15, erect-patent to arcuate-patent, subimbricate or not imbricate, ± ovate, ca. 8.5–10.0 × 3.0–4.5 (–6.0) mm, surface ± evenly olivaceous-green or dark so, with a relatively abrupt transition in a whitish-membranous border usually 0.5–1.0 mm wide, margin ± glabrous, apex with relatively small horns; inner phyllaries dark olivaceous-green, 12–16 mm, callose to corniculate, sometimes coalescing. Outer ligules ± flat, faintly striped greyish-pinkish outside, teeth dirty yellow. Stigmas ± yellow or dirty yellow. Pollen present, pollen grains irregular in size. Achenes unknown. – Agamospermous. – Fig. 12 .

Diagnostic notes:—The very robust growth of T. platycranum , the extremely broad, truncate involucre, erect-patent or arcuate patent large ovate outer phyllaries and ± yellow stigmas are diagnostic. The absence of pollen, reported in the protologue, is considered a mistake, as the LE isotype has anther tubes with irregular pollen grains.

Distribution:—This species is known from a single collection from the vicinity of Petropavlovsk-Kamchatskiy, Kamchatka.

Figures

FIGURE 12. Taraxacum platycranum. General habit and a detail of young flower head (both LE, no. det. 6038).