Taraxacum acricorne Dahlstedt (1930: 220)

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 : 47

15. Taraxacum acricorne Dahlstedt (1930: 220)

Type:—[ RUSSIA, Kamchatka] Kamtchatka, Petropavlovsk [Petropavlovsk-Kamchatskiy], “Signal Hill”, 25 Jun 1928, W. Eyerdam ( S 05-7559 !, holotype; LE, no. det. 6140, isotype) .

Etymology:—With horns at an apical position.

Plants small but of robust appearance, to ca. 12 cm tall. Petiole winged to narrowly winged, usually suffused pinkish, tunic absent. Leaves ± mid-green, subglabrous, narrowly oblong in outline, usually 6–10 × 1.4–2.3 cm, pinnatifid to pinnatisect, with 3–4 pairs of narrowly deltoid-triangular to linear-triangular, patent to ± recurved lateral segments, distal margin straight to ± concave, usually with a single little tooth or a shallow incision, or entire, proximal margin ± straight, entire; terminal segment triangular to trilobed, entire, with patent basal lobules; interlobes relatively long, entire or with a single thin tooth; mid-vein light green. Scapes brownish green, arachnoid, ± equalling leaves. Capitulum yellow, 3.0– 3.5 cm wide. Involucre dark olivaceous-green, 8–9 mm wide and rounded at base. Outer phyllaries (11) 13–15, some appressed, most of them loosely appressed to erect, ± not imbricate, narrowly lanceolate to linear-lanceolate, ca. 7.0–9.5 × (1.8–) 2.0– 2.7 mm, usually with a thin black-green middle line, deep olivaceous-green, with a very gradual transition into a paler (gradually to membranous) border 0.4–0.7 mm wide, margin sparsely ciliate distally, apex with purplish black-green, thin, perpendicular to suberect horns 1.0– 1.5 mm long; inner phyllaries 13–16 mm long, narrow, ± not coalescing, apex ± corniculate. Outer ligules ± canaliculate, striped grey or very faintly grey outside. Stigmas discoloured, green-yellow. Pollen present, pollen grains irregular in size. Achenes (no. det. 37798) light greyish stramineous-brown, 3.9–4.2 × ca. 0.9 mm, body subdensely to densely covered with erect-patent narrow squamules (up to ca. 0.3 mm long), subgradually to gradually narrowing into a subcylindrical cone ca. 0.5–0.7 × 0.3 mm, beak 9.5–11.0 mm, pappus white, ca. 5.0– 5.5 mm. – Agamospermous. – Fig. 28 , 29 .

Diagnostic notes:— Taraxacum acricorne is distinct in having narrow, loosely appressed to erect, relatively broadly but inconspicuously bordered outer phyllaries with thin, long horns. It is similar to T. leptoceras which has darker, spotted or blotched leaves, narrower border to outer phyllaries, and usually erect-patent to erect-arcuate outer phyllaries. However, in the absence of achenes, and with rather scanty material to be compared, the taxonomic identity of the names T. acricorne and T. leptoceras cannot be excluded. Taraxacum perdecorum differs from T. acricorne in blotched interlobes, usually yellow stigmas and a broadly conical cone.

There are another two gatherings tentatively included under the umbrella of T. acricorne . One comes from Kamchatka, the other from Ongudai District, the Altai Republic. The achene description is based on the latter, cultivated sample (no. det. 37798), and the achenes are ± close to those of T. leptoceras .

Distribution:—Known from a locality near Petropavlovsk-Kamchatskiy and from Bystrinskiy District, both Kamchatka. Krasnikov (1997) reported its occurrence from a number of regions but a revision of these records is needed. There is a gathering from the Altai that is close to T. acricorne , and we give it for further study.

Specimens examined:— RUSSIA. Kamchatka, Bystrinskiy District, SE. of Ichinskaya Sopka volcano, valley of Babav R., 55°38.959’N, 157°56.338’E, 881 m, 15 Jul 2015, V. V. Buryy T097 (herb. V. V. Buryy, no. det. 36928). – Less certain identification :— Altai Republic, Ongudai District, 13 km WSW of the village of Belyy Bom, Shirlak Waterfall , 50°20’38.4’ N, 87°13’16.1’ E, 950 m, 25 Jul 2011, J. Danihelka, cult. as JŠ 9683 ( PRA, no. det. 37798) .

Figures

FIGURE 28. Taraxacum acricorne. General habit (LE, no. det. 6140, isotype).

FIGURE 29. Taraxacum acricorne. A, General habit of a plant on the holotype herbarium sheet (S 05-7559); B, Achenes (PRA, no. det. 37798).