Taraxacum lenense Tzvelev

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 : 87-89

34. Taraxacum lenense Tzvelev in Tzvelev & Yurtzev (1984: 190)

Type:—[ RUSSIA, Sakha Republic] Yakutskaya ASSR, severnaya okonechnost’ Kharaulakhskogo khrebta, pravyy bereg Bykovskoi protoki r. Leny , okresnosti p. Sokol [Lower Lena, northern Kharaulakh Range, right bank of Bykov river branch of Lena river, vicinity of Sokol village, a hilly right bank of Lena 8 km south of Stolb Island, schist], 72°20’ N, 125°40’ E, goristyy pravyy bereg Leny v 8 km yuzhnee o. Stolb , slantsevaya osyp’, 23 Aug 1956, T. G. Polozova & B. A. Yurtzev ( LE, no. det. 6084, holotype; another seven plants as isotypes in LE: no. det. 17146, 17147, 17148, 17149, 17150, 17151) .

Etymology:—Named according to the Siberian Lena River, the longest river in Russia.

Plants relatively slender, ca. 12–14 (–20) cm tall. Petiole unwinged, often suffused purplish, tunic ± absent. Leaves deep green, subglabrous, linear-oblanceolate in outline, usually 5–8 × 0.7–1.3 cm, later longer, ± pinnatipartite, usually with 2–3 (4) pairs of triangular lateral segments, distal margin usually sigmoid (with broad base), entire or seldom with sparse minute teeth, proximal margin ± patent, entire; terminal segment large, triangular-subhastate, ca. 1.5 × 1.1 cm, entire or subentire, basal lobules short, patent, acute; interlobes 2–4 mm wide, usually entire. Scapes brownish green, often suffused purplish proximally, arachnoid, densely so below capitulum, overtopping leaves. Capitulum deep yellow, ca. 2 cm wide. Involucre blackish green, 7–8 mm wide and narrowly rounded at base. Outer phyllaries 13– 16, ± appressed, ± subimbricate, usually narrowly lanceolate (the innermost ones to linear-lanceolate, the outermost sometimes ovate-lanceolate), usually 4–6 (–7) × (1.5–) 2.0– 2.5 mm, surface black-green, distally often suffused purple, margin almost invisible, ± whitish, less than 0.1 mm wide, margin sparsely ciliate, apex with distinct horns to 1 mm long; inner phyllaries black-green, 11–13 mm long, later elongating, apex ± corniculate or ± flat. Outer ligules ± flat, striped grey-purple outside, teeth dark grey. Stigmas dark discoloured. Pollen present, pollen grains irregular in size. Achenes grey, sometimes deep grey-olivaceous, 5.0–5.3 × 1.0– 1.3 mm, body densely covered with coarse, relatively short, erect or curved spinules and squamules in upper 1/3–1/2, subgradually narrowing into a subcylindrical to subconical, relatively thick cone (0.5–) 0.6–0.7 × ca. 0.4 (–0.5) mm; beak ± thin, ca. 0.2–0.25 mm thick, ca. 5–6 mm long, pappus yellowish or yellowish white, ca. 6.5 mm long. – Agamospermous. – Fig. 57 , 58 .

Diagnostic notes:—The narrow, dark, indistinctly, narrowly bordered, conspicuously horned outer phyllaries, and pure grey or deep grey-olivaceous, densely spinulose achenes make a diagnostic character combination.

Distribution:—Known from a single macrolocality on the lowermost Lena River; the gathering is very rich and representative, however.

Comparison of the North Asiatic Taraxacum sect. Borealia with plants from North America

As regards the sectional and species diversity of Taraxacum , both regions are comparable. The most striking difference is the low species diversity of T. sect. Arctica in Alaska, Yukon and the NWT. This phenomenon, nevertheless may be a consequence of the lower level of exploration, or the problematic cultivation of Arcticoid plants ( Haglund 1946).

Taraxacum sect. Borealia , when compared between the above two main regions, also exhibits quite striking features. The American species very often do not develop pollen, which is an attribute seldom encountered in Asiatic Russia. The same asymmetry concerns the achene colour: the American plants frequently have achenes reddish, cinnamon, brown, ochraceous-reddish etc. while the Asiatic ones predominantly have light greyish straw-brown achenes. As regards the reproduction mode, in Russia the sexuality is extremely rare (see T. kolymense, Kirschner et al. 2022a , and T. leucocarpum ). In Alaska and Yukon, the sexuality in T. sect. Borealia remains unknown but it is getting more common towards the south (Montana, California).

There are several species groups with the greatest diversity in North America that are to be considered when studying Russian Asiatic plants.

group of T. lacerum ( T. sublacerum )

group of T. ceratophorum s. str. ( T. dumetorum , T. kodiakense , T. subtrigonum )

group of T. lateritium group of T. anadyrense – T. leucoglossum

Predominantly Alaskan and Aleutian species with outer phyllaries imbricate, short, of a broad shape and usually with a distinct but relatively narrow border

There is a distinctive group of species centred in the Aleutians, the Pribilof Islands and adjacent parts of continental Alaska, and confined to Kamchatka and islands in Bering Sea on the Russian side. It is characterized primarily by the numerous, ovate or even broadly ovate, conspicuously imbricate, variably but usually narrowly bordered outer phyllaries with blackish abaxial surface, relatively robust growth, presence of pollen and discoloured stigmas. The group includes T. ceratophorum s. str. (= T. trigonolobum ), a species widespread in the Aleutians, on Kodiak Isl., Commander Isl., the SE. Kamchatka (with sites in C. Kamchatka), distinct in having light greyish stramineous-brown achenes, conspicuous deltoid-triangular leaf lobes, densely hairy scapes etc. Other, similar species to be mentioned are T. callorhinorum (red achenes), T. chamissonis (sayal brown achenes), T. pribilofense (also sayal brown achenes but conspicuously dentate leaf lobes and purple petioles), and T. subtrigonum , a new species described from central Kamchatka below (narrow, pale petioles, sparse idumentum). There are similar, probably not closely related species in Alaska, T. kodiakense (lower number of outer phyllaries that are not clearly imbricate) or T. mitratum . In Kamchatka, there are two rather unclear species requiring a new material, marginally belonging to this group: T. latisquameum and T. malaisei . The former has outer phyllaries close to those of T. ceratophorum s. str., and is reported not to develop pollen (its achenes remain unknown), the latter is also believed not to have pollen, and its numerous, imbricate outer phyllaries are ± broadly bordered, and the type plant may be closer to T. hultenii .

Figures

FIGURE 57. Taraxacum lenense. A, a detail of involucre and florets (LE, no. det. 6084, holotype); B, achenes (LE, isotype). The achene colour is darker grey when viewed in daylight.

FIGURE 58. Taraxacum lenense. The holotype specimen (LE, no. det. 6084).