Tragopogon dubius Scop. (Euras.) – A rare but locally much increasing, naturalized alien. First recorded in 1939 (Verloove 2014) and 1954 (Verloove 2006), respectively in coastal dunes in Koksijde and on a railway bank in Sint-Kathelijne-Waver. These first appearances probably were merely ephemeral. The first naturalized populations were found in the port of Gent (Robbrecht & Jongepier 1986, 1989), mostly since 1985 but one collection dates back to 1971 (initially taken for Scorzonera hispanica). By now, Tragopogon dubius is abundantly naturalized in this area. Since 1997 it is increasingly recorded in coastal dunes (often more or less ruderalized), especially between Adinkerke and Nieuwpoort and around Zeebrugge (possibly introduced via the port there). Also since the 1990’s much extending in the port of Antwerpen and now widely naturalized (see Van Landuyt 2006 for its actual distribution pattern in Flanders). In Wallonia known from some coal mining spoil heaps around Charleroi since 2008, where it now locally occurs in abundance. Elsewhere in Belgium only occasionally found and often ephemeral but likely to become more widespread in a near future.
Unlike native Tragopogon pratensis, T. dubius usually occupies dry and sunny man-made habitats (waste land, sandy road verges, sand raised sites, railway tracks, coal mining spoil heaps, etc.). However, it is also found in coastal dunes, even in un- or only slightly disturbed places (similar behavior has been noticed for Erigeron sumatrensis).
Most Belgian populations of Tragopogon dubius are very typical (wide leaves, distinctly inflated peduncle, more numerous involucral bracts, etc.; see Richardson 1976) and apparently represent subsp. major (Jacq.) Vollm. (syn.: T. major Jacq.). Some populations are less typical and more closely resemble Tragopogon pratensis or are more or less intermediate. However, the occurrence of hybrid populations (T. xcrantzii Dichtl.) is rather unlikely since hybrids are believed to be (nearly) sterile (Soltis 2006). Tragopogon dubius, as traditionally understood, includes all plants with yellow flowers and swollen peduncles under capitula. However, it may well be that two or more cryptic additional species are accommodated in what now is called T. dubius (e.g. Suárez-Santiago & al. 2011, Mavrodiev & al. 2012).
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Selected literature:
Bobowicz M.A. (1984) Species variability in Tragopogon L. genus (Asteraceae) in Poland. 1. Interspecific variability of Tragopogon dubius Scop., Tragopogon pratensis L., Tragopogon orientalis L., Tragopogon heterospermus (Schweigg.) C. Rgl. and Tragopogon porrifolius L. Bull. Soc. Amis Sci. Lett. Poznań, ser. D – biol. 24: 109-121.
Clements D.R., Upadhyaya M.K. & Bos S.J. (1999) The biology of Canadian weeds: 110. Tragopogon dubius Scop., Tragopogon pratensis L. and Tragopogon porrifolius L. Canad. J. Pl. Sci. 79: 153-163. [available online at: http://pubs.aic.ca/doi/pdf/10.4141/P98-007]
Feder J. (2003) Zur Verbreitung von Tragopogon dubius Scop. in Niedersachsen und Bremen (Nordwest-Deutschland). Braunschweiger Naturkdl. Schr. 6(4): 775-788.
Geyer H.J., Loos G.H. & Büscher D. (2008)Rezentvorkommen von Adventivpflanzen und Apophyten auf Bahnhöfen im mittleren Westfalen und ihre Ausbreitungstendenzen. Braunschweiger Geobotanische Arbeiten 9: 177-188. [available online at: http://rzbl04.biblio.etc.tu-bs.de:8080/docportal/servlets/MCRFileNodeServlet/DocPortal_derivate_00012669/GeyerLoosBues_BahnhofPflanzen.pdf]
Jogan N. (2013) Yellow goatsbeard Tragopogon dubius Scop. (Asteraceae): confirmation of its dubious occurrence in Central Slovenia. Natura Sloveniae 15(2): 5-11. [available online at: http://web.bf.uni-lj.si/bi/NATURA-SLOVENIAE/pdf/NatSlo_15_2_1.pdf]
Kern J.H. (1957) Tragopogon dubius Scop. in Nederland. Correspondentiebl. Dienst Florist. Veg.-Onderz. Ned. 2: 17.
Macaya J. (2010) Tragopogon dubius Scopoli (Asteraceae), un nuevo registro para la flora advena de Chile. Chloris Chilensis 13(2). [available online at: http://www.chlorischile.cl]
Richardson I.B.K. (1976) Tragopogon. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 4. Cambridge University Press, Cambridge: 322-325.
Robbrecht E. & Jongepier J.-W. (1986) Floristische waarnemingen in de kanaalzone Gent-Terneuzen (België, Oost-Vlaanderen & Nederland, Zeeuws-Vlaanderen), vooral van 1981 tot 1985. Dumortiera 36: 6-21. [available online at: http://alienplantsbelgium.be/sites/alienplantsbelgium.be/files/dum36p6.pdf]
Robbrecht E. & Jongepier J.-W. (1989) De synantrope flora van het havengebied van Gent (België, Oost-Vlaanderen), waarnemingen van 1986 tot 1988. Dumortiera 44: 1-12. [available online at: http://alienplantsbelgium.be/sites/alienplantsbelgium.be/files/dum44p1.pdf]
Soltis P.S. (2006) Tragopogon. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 19. Oxford University Press, New York-Oxford: 303-306. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=133279]
Suárez-Santiago V.N., Díaz de la Guardia C., Soltis D.E., Soltis P.S. & Blanca G. (2011) Tragopogon lainzii, a New Species of Tragopogon (Asteraceae) Segregated from T. dubius: Evidence from Morphological and Molecular Data. Systematic Botany 36(2): 470-480.
Van der Meijden R. (1984) Tragopogon dubius Scop. in Nederland. Gorteria 12(2): 23-25.
Van Landuyt W. (2006) Tragopogon dubius. In: Van Landuyt W., Hoste I., Vanhecke L., Van den Bremt P., Vercruysse W. & De Beer D., Atlas van de flora van Vlaanderen en het Brussels gewest. Instituut voor Natuur- en Bosonderzoek, Nationale Plantentuin van België en Flo.Wer: 882.
Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.
Verloove F. (2006) Catalogue of neophytes in Belgium (1800-2005). Scripta Botanica Belgica 39: 89 p.
Verloove F. (2014) Liste des néophytes de l’herbier de Léon Delvosalle déposés à BR. In: Fabri R., Léon Delvosalle (1915–2012) : Une vie au service de la cartographie floristique. Plant Ecology and Evolution 147(2): 8 pp. [available online at: http://www.ingentaconnect.com/content/botbel/plecevo/2014/00000147/00000002/art00014/supp-data/content-plecevo_sup-data_00236]