Taraxacum macilentum Dahlstedt (1906: 17)

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 : 70

26. Taraxacum macilentum Dahlstedt (1906: 17) .

Type:—[ RUSSIA, Sakha] Sib., Lena, Kisiljach (ca. 72°), 7 [Jul] 1898, N. H . Nilsson 58a ( S 13-4651 !, lectotype designated by Tzvelev 1987b: 285) [the label reads 7 Jun 1898, which is a mistake because, in the high Arctic, it is too early for Taraxacum to have flowers in the early June]; isolectotype: [ RUSSIA, Sakha] Plantae lenenses subarcticae, Sibiria , oblastia Jakutsk , Kissiljach , in declivibus arenosis ad flumine, 7 Jul 1898, N. H . Nilsson ( LE 01082216 , no. det. 6042). – Residual syntypes:—[ RUSSIA, Sakha] Sib. , Lena , Bulkur (nära 72°), 26 Aug 1898, N. H . Nilsson 93 ( S 13-4653 !). – [ RUSSIA, Sakha] Sib., Lena , Balaganasch (ca. 73°35’), 15 Jul 1898, N. H . Nilsson 62-4a ( S 13-4650 !) [all the previous labels were transcribed by Dahlstedt in 1905, on the basis of little field labels written by N. H. Nilsson]. – [ RUSSIA, Krasnoyarsk] Sibiria, Jenisei , Verschininskoje , 27 Jul 1876, M . Brenner ( H 1779873 !). – [ RUSSIA, Krasnoyarsk] Sibiria, ad flum. Jenisei , Kantsika , 19 Jul 1876, J. R . Sahlberg ( H 1742741 !) .

Etymology:—Meagre, thin.

Plants glabrous or subglabrous, slender, usually 8–20(–25) cm tall. Petiole greenish, sometimes purplish, winged,rarely almost unwinged basally. Leaves (linear) linear-oblanceolate in outline, 6–12 (–15) × 0.7–1.5 cm, typically dentate or pinnatilobed, occasionally pinnatipartite, with 3–4 (–5) pairs of ± patent, triangular, entire, acute lateral lobules or lobes; terminal lobe typically elongated, oblong, acute or obtuse; sometimes leaf almost undivided, with dentate margin. Scapes typically sparsely arachnoid below capitulum, rarely subglabrous, overtopping leaves, rarely subequalling them. Capitulum yellow, medium-sized, ca. 3.5 cm wide. Involucre dark, blackish green, sometimes medium green, ca. 8 mm wide and ± narrowly rounded at base. Outer phyllaries usually (8) 10–15 (17), ± appressed, subimbricate, ovate to lanceolate, 2.5–5.0 × (1.3–) 1.5–2 (–2.3) mm, surface typically evenly black-green, border absent, occasionally with inconspicuously developed or very narrow border ca. 0.1 mm wide, margin glabrous or sparsely ciliate, apex with a black or black-purple horn to 1.5 mm long; inner phyllaries ca. 9–15 mm long, corniculate. Outer ligules striped greenish grey. Stigmas dark discoloured. Pollen present. Achenes greyish or yellowish-brown, ca. 4.5 × 1.0 mm, body variably spinulose in upper 1/3, subabruptly to subgradually narrowing into a subcylindrical cone ca. 0.7–1.0 × 0.4 mm; beak thin, 8–10 mm long, pappus white, ca. 7 mm long. – Agamospermous. – Fig. 44 , 45 .

Notes on the variation and identity:— Taraxacum macilentum as understood here is a rather polymorphic species, with a substantial variation in leaf shape, outer bract shape and fruit color. This difficult group requires further study. It may consist of several taxa, or, vice versa, it may include variation as a consequence of (partial) sexuality. One of the superficially similar taxa is T. leucocarpum , a species with sexual reproduction (but see the diagnostic notes in the treatment of the latter). There is also a certain resemblance between T. macilentum and T. alaskanum .

Distribution and habitat:—According to the material available, T. macilentum has a rather wide distribution in the Russian Arctics from the Urals to the Bering Sea. However, it seems especially common in the middle part of its range, from Taimyr to West Chukotka. It grows in humid tundra habitats and in a grassland mosaic along rivers.

Specimens examined (a selection of individuals approaching most closely the type material):— Yakutskaya SSR, lower reaches of Lena River , right bank upstream of the Tit-Ary Island, downstream from Arangastakh River, loose substrate, 20 Aug 1957, B. A . Yurtsev ( LE 01229531 !). – Yakutskaya SSR, Bulunskiy District , lower reaches of Olenek River, right bank, mouth of Tas-Yuryakh River, sandy riverbank, 7 Aug 1960, B. A . Yurtsev ( LE 01229532 !). – Yakutskaya SSR, lower reaches of Lena River , Tuora-Sis Mt Range , basin of Naelaegaer River, its tributary Daldyn- Eznigi River, grassy gravel, 11 Aug 1957, B. N . Norin & B. A . Yurtsev ( LE 01229533 !). – Yakutskaya Region, Verkhoyansk District, Ust’yanskiy Ulus, Kazach’ye Village, mountain on the right bank of Kazach’ya River, 22 June 1903, A . D. Polyak ( LE!). – Yakutskaya SSR, Nizhnekolymskiy District, near the Lake yakutskoye, yodoma [a kind of hill], 18 Aug 1975, T. M . Koroleva & V. V . Petrovskiy ( LE!). – Yakutia, lower reaches of Lena River , Bykovskiy Peninsula , Neyolova Bay 2, 5 km south from Bykovo Village, landslide, 16 Aug 1955, E. V . Dorogostayskaya & B. A . Yurtsev ( LE!). – Yakutia, lower reaches of Lena River , Kharaulakhskiy Mt Range against Tit-Ary Island, steep bank of Lena River, 6 Aug 1956, O. V . Pigulevskaya ( LE!). – Yakutskaya SSR, Bulunskiy District , lower reaches of Olenek River, near the Taimylyr Village, riverbank baydzharakhs, alluvium substrate with turf, 4 Aug 1960, B. A . Yurtsev ( LE!). – Yakutskaya SSR, Nizhnekolymsk District , 15 km east of Votapkrytkin Lake , 2.5 km NE of Kyoni yodoma [hill], middle part of SE yodoma slope, 27 Jul 1957, Satalkina ( LE!). – Yakutia, coast of Laptev Straight, Svyatoy Nos Cape, western coast, 30 Jul 1961, L . Budantsev & I . Sveshnikova ( LE!). – Yakutskaya SSR, Svyatoy Nos Cape, south slope, tundra composed of grasses, lichens and mosses in the upper part of small valley, 13 Aug 1976, I. N . Safronova ( LE!). – Less certain identification:—[ RUSSIA, Arctic Siberia] SW. Taimyr, Putoran Plateau, S . vicinity of the Ayan Lake , near the mouth of Amnundakta R ., 69°03’50.4” N, 94°10’08.75” E, 10 Jul 2019, I. N . Pospelov 19-1131 ( NSK, photo!). – SW. Taimyr, Putoran Plateau, S . vicinity of the Ayan Lake , meadow on a rock in a canyon, 68°59’10.0” N, 94°16’38.3” E, 17 Jul 2019, I. N . Pospelov 19-1149 ( NSK, photo!) .

Figures

FIGURE 44. Taraxacum macilentum. A detail of flower heads (S 13-4651, lectotype).

FIGURE 45. Taraxacum macilentum. General habit (LE 1229531).