4. Erigeron floribundus (Kunth) Schultz-Bip. (syn.: Conyza floribunda Kunth; incl.: E. bilbaoanus (J. Rémy) Cabrera, Conyza bilbaoana J. Rémy) (S-Am.) – A rare but locally naturalised and much increasing alien. Discovered in small number in the city of Kortrijk in 1999, doubtlessly soon after its introduction (Verloove 2001). At present much extending locally and now present in several neighbouring cities and villages in the southernmost parts of West-Vlaanderen as well (Bissegem, Menen, Moen, Spierre, Wevelgem,…). Furthermore also known from Brugge, Dadizele, Nieuwpoort, Roeselare, Ursel,… Recorded in abundance on an old quay along river Schelde in Spierre-Helkijn in 2008, close to the Wallonian territory. Also spreading in Hooglede where Erigeron floribundus was formerly introduced in the garden of the author. Apparently up to recently confined to the province of West-Vlaanderen but surely overlooked elsewhere in Belgium. Discovered in 2009 at two locations in the Kempen, twice in abundance (Beerse, foot of fence near a brick factory and Nijlen, waste land along Netekanaal). Since 2012 also known from Wallonia when it was discovered in abundance on rough ground near Mons and since 2015 from the Brussels port area (exceedingly common, for instance, on ground heaps in a railway yard and will doubtlessly further expand from there). This species is the most recent representative of the genus in Belgium but seems to spread in the fastest way.
Erigeron floribundus is poorly known in Belgium. It shares the nearly glabrous, ciliate leaves and small capitulae with Erigeron canadensis but has tubular florets that are 5-lobed, the laminae of the ligular florets is lacking and it has a dull, greyish-green appearance (plants are more hirsute hairy). In addition, the inflorescence of Erigeron floribundus is much more open and never cylindrical.
As treated here, Erigeron floribundus includes E. bilbaoanus. However, according to Sell & Murrell (2006) both are distinct and occur in the British Isles. The Belgian plants rather approach “true” Erigeron bilbaoanus.
Erigeron bilbaoanus is a taxonomically critical taxon. Pruski & Sancho (2006) recently subsumed it under E. sumatrensis (as var. leiotheca (S.F. Blake) Pruski et G. Sancho). However, it is not sure if these New World plants correspond with European Erigeron bilbaoanus. In the past it has been combined under Erigeron bonariensis as well and, in fact, this plant is more reminiscent of E. canadensis.
A hybrid with native Erigeron acris has been repeatedly recorded lately in the British Isles. It was given the name xConyzigeron stanleyi Mundell (Mundell 2016).
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Selected literature:
Dauphin P. (1995) Sur l’expansion de Conyza floribunda en Gironde. Bull. Soc. Linn. Bordeaux 23(2): 77-78.
Mundell A.R.G. (2016) The genus Conyza in Britain and a name for the hybrid between Erigeron acris and Conyza floribunda (Asteraceae). New J. Bot. 6(1): 16-20.
Nesom G.L. (2018) Erigeron floribundus and E. sumatrensis (Asteraceae) in the USA and Mexico. Phytoneuron 2018-27: 1–19. [available online at: http://www.phytoneuron.net/2018Phytoneuron/27PhytoN-Conyzasumatrensis.pdf]
Phillips B. (1997) Conyza bilbaoana confirmed from Surrey. BSBI News 76: 60-61.
Philp E. (2002) Conyza bilbaoana in Kent. BSBI News 89: 32.
Pruski J.F. & Sancho G. (2006) Conyza sumatrensis var. leiotheca (Compositae: Astereae), a new combination for a common neotropical weed. Novon 16: 96-101.
Reynolds S. (1997) Conyza bilbaoana also in Ireland. BSBI News 74: 44-46.
Sell P. & Murrell G. (2006) Flora of Great Britain and Ireland. Vol. 4 Campanulaceae – Asteraceae. Cambridge University Press, Cambridge: XXVIII + 624 p.
Stanley P. (1996) Conyza bilbaoana J. Rémy – new to South Hampshire (vc 11) and to Britain. BSBI News 73: 47-49.
Verloove F. (2001) Conyza bilbaoana J. Rémy, Cotoneaster x watereri Exell en Erigeron karvinskianus DC., nieuw voor de Belgische flora in Kortrijk. Dumortiera 78: 24-27.
Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.
Verloove F. (2006) Conyza bilbaoana. 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: 303-304.