Taraxacum (sect. Crocea) Christiansen 1942
Creators: name: Štěpánek, Jan
name: Kirschner, Jan
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Asterales
Asteraceae
Taraxacum

description: B.  Taraxacum sect. Crocea  Christiansen (1942: 255)   
 ≡ Taraxacum subsect. Crocea (M. P. Christ.) Richards (1972: 38)   
 Type:— Taraxacum croceum Dahlstedt (1901: 12)   
 Type:— Sweden [Hälsingland], Vänsjö, Vänsjöhammaren, 12. Jul 1898 M. Östman (S 05-7995!, lectotype, designated by Lundevall & Øllgaard 1999: 74)   
 = Taraxacum sect. Fontana van Soest (1959: 103)   
 ≡ Taraxacum subsect. Fontana (van Soest) Doll (1982: 538)   
 Type:— Taraxacum fontanum Handel-Mazzetti (1907: 100)   
 Type:— Austria, an feuchten Stellen zwischen Steinen in der Rinne ober dem Kaserl im Sendersthal bei Innsbruck gegen das Pleisenjoch, ca. 1800 m, 23 Jul 1903, H. Handel-Mazzetti (WU, no. det. 8943, lectotype, designated by Kirschner & Štěpánek 1997: 92).    Introduction   
 The Arctic-Alpidic group characterized by a large disjunction between the northernmost Europe and the Alps, was first recorded from the Balkans by Handel-Mazzetti (1907, as T. fontanum), then by Hayek (1931, as T. officinale var. fontanum, and finally by Doll (1978). A detailed comparison of the northern species of T. sect. Crocea revealed their sectional identity with the Alpine species referred to as T. sect. Fontana. The first formal synonymization of these two sectional names is published in the present paper, in accordance with the opinion of other experts in Taraxacum (C. I. Sahlin, pers. comm. 1984; I. Uhlemann, a paper in prep.).   
 There are more than 120 northern species and up to 20 distributed in south-central and southern Europe; it should be added that T. sect. Crocea is known to occur in Greenland, Alaska and Canada. With a single, notable exception, all the species are agamospermous. In Bulgaria, there are four agamosperms, and the single sexual diploid species, T. paludosiforme Doll.   
 The most conspicuous features of T. sect. Crocea are leaves with a low number of short and broad lateral segments, broadly winged petioles of outer leaves, outer phyllaries usually appressed to loosely appressed, sometimes their distal part arcuate recurved to arcuate-patent, deep yellow to golden yellow (almost orange-yellow) capitula, and achenes with a subabrupt transition between achene body and ± conical to subcylindrical cone.    Description   
Plants (10–) 15–25 (–30) cm tall but usually ± slender, not robust; plant base without tunic, usually glabrous to sparsely arachnoid.Petioles broadly winged (mostly,and most conspicuously,in outer leaves), usually pale green, seldom suffused purplish, mainly on mid-vein. Leaves usually remotely and shallowly pinnatilobed, sometimes almost undivided, or pinnatisect, glabrous, subglabrous or sparsely arachnoid. Scapes most often glabrous to sparsely arachnoid (mainly just below capitulum), usually overtopping leaves. Capitulum usually deep yellow or deep golden yellow, outer ligules ± flat. Involucre most often olivaceous-green to dark so, often pruinose; outer phyllaries appressed to loosely appressed, less often erect, sometimes with arcuate-patent distal part, most often ovate-lanceolate to lanceolate, not imbricate or slightly so, surface ± evenly dark olivaceous green to grey-green, rarely darker or lighter, usually with a very narrow, inconspicuous paler, membranous or whitish border, sometimes unbordered, apex flat, margins subglabrous. Achenes light greyish stramineous-brown, stramineous-brown or light beige, usually 4–5 mm long, body subdensely to densely spinulose above, subabruptly narrowing into a short, subconical, conical, less often subcylindrical cone; beak thin, usually 6–10 mm long; pappus white, usually 5.5–7.5 mm long.   An identification key to the Bulgarian members of Taraxacum sect. Crocea   
 1 Pollen grains regular, of ± uniform size..................................................................................................... 5. T. paludosiforme Doll   
– Pollen grains irregular, of conspicuously variable size.................................................................................................................... 2  
 2 Achenes light rusty-brown; outer phyllaries very pale green, almost translucent, with a distinct, broad paler border, usually narrowly lanceolate, most of them arcuate to arcuate-patent at and after full anthesis; involucre narrow, 7–8 mm wide near the base............................................................................................................................................................................ 10. T. amoenulum, sp. nov.   
– Achenes light brownish, light greyish stramineous-brown, light beige or deep stramineous-brown; outer phyllaries deep olivaceousgreen to dark blackish green, or light to pale green, very narrowly bordered, usually lanceolate to ovate-lanceolate, most of them loosely appressed, sometimes apically arcuate at and after anthesis; involucre medium broad, 8–10 mm wide near the base...... 3  
 3 Achene cone conical to subconical, 0.3–0.5 mm long; outer phyllaries dark green to black-green; stigmas dark discoloured............................................................................................................................................................................. 9. T. fornicatum, sp. nov.   
– Achene cone cylindrical, subcylindrical or subconical, 0.5–0.9 mm long; outer phyllaries light green to deep olivaceous-green; stigmas light discoloured.................................................................................................................................................................. 4  
 4 Outer ligules mostly not striped or some faintly striped outside; achenes 4.7–5.1 mm long........... 8. T. pseudosplendens, sp. nov.   
– Outer ligules distinctly striped outside; achenes 3.5–4.8 mm long.................................................................................................. 5  
 5 Petioles usually pale greenish; achene body thick, 1.1–1.4 mm wide........................................................ 7. T. splendens, sp. nov.   
 – Petioles usually suffused purple; achene body slender, 0.9–1.0 mm wide............................................................. 6. T. vile, sp. nov.
description: Published as part of Štěpánek, Jan & Kirschner, Jan, 2022, A hotspot of endemism: Oreophytic Taraxacum species (Compositae, Crepidinae) in the mountains of Bulgaria, pp. 1-139 in Phytotaxa 569 (1) on pages 30-31, DOI: 10.11646/phytotaxa.569.1.1, http://zenodo.org/record/7235182