1. Digitaria aequiglumis (Hack. et Arechav.) Parodi (S-Am.) – A rare but much increasing, locally naturalised agricultural weed in maize fields in a wide area around Gent. Initially discovered in 2001 in Sleidinge, soon afterwards also in Adegem in 2004 (Hoste 2005, 2006). A subsequent herbarium revision yielded an additional record, so far the oldest from Belgium: Bassevelde (1997). This may have been its original area of introduction. Several new populations were discovered since 2006: Digitaria aequiglumis may either have been overlooked for quite some time, or acts as a fast spreading weed. New large populations were found in 2006 near Beervelde (Lochristi, where - by 2015 - it has much expanded towards Lokeren) and in 2008 in Evergem. Again in 2008, a new locality was discovered near Lovendegem and in 2009 in Bellem (near Aalter), a considerable extension of its known distribution range to the west. In 2015 it was also found in abundance in maize fields near Deinze and in 2017 in Lembeke (Kaprijke) as well. In 2018 it was recorded for the first time in the province of West-Flanders, in Ruiselede. Digitaria aequiglumis by now is firmly established and possibly still under-recorded as a result of confusion with other species of Digitaria.
Contrary to Ryves & al. (1996) spikelets of Digitaria aequiglumis can be either glabrous or shortly pubescent. As a matter of fact the type collection shows slightly pubescent spikelets. Forms with glabrous spikelets have been segregated as var. laetevirens (Mez) Henrard (Henrard 1950, Vega & Rúgolo de Agrasar 2002). The Belgian collections correspond well with var. aequiglumis.
Digitaria aequiglumis seems in expansion in several parts of Europe. It is well documented from southwestern France (Vivant 1980; Verloove 2000) and was recently found on railway yards in Germany as well (Abts 1994).
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Selected literature:
Abts U.W. (1994) Neue und bemerkenswerte Blütenpflanzen des Niederrheins unter besondere Berücksichtigung kritischer und schwer unterscheidbaren Sippen. Floristische Rundbriefe 28: 6-24.
Henrard J.Th. (1950) Monograph of the genus Digitaria. Universitaire Pers, Leiden: XXI + 999 p.
Hoste I. (2005) Digitaria aequiglumis in Sleidinge (O.-Vl.), nieuw voor de Belgische flora. Dumortiera 84: 21-23.
Hoste I. (2006) Digitaria aequiglumis. 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: 340.
Lepschi B.J. & Macfarlane T.D. (1997) Digitaria aequiglumis (Poaceae), a new weed for Western Australia. Nuytsia 11(3): 425-427
Ryves T.B., Clement E.J. & Foster M.C. (1996) Alien grasses of the British Isles. BSBI, London: XX + 181 p.
Vega A.S. & Rúgolo de Agrasar Z.E. (2002) Novedades taxonómicas y sinopsis del género Digitaria (Poaceae: Panicoideae: Paniceae) en Bolivia. Darwiniana 40: 171-190.`
Verloove F. (2000) N° 19878 Digitaria aequiglumis (Hack. et Arech.) Parodi. Soc. Ech. Pl. Vasc. Eur. Bass. Médit., Bull. 28: 106.
Vivant J. (1980) Phanérogames adventices se naturalisant dans les Landes et les Pyrénées-Atlantiques. Bull. Soc. Bot. Fr. 127: 289-295.
Webster R.D. & Hatch S.L. (1990) Taxonomy of Digitaria section Aequiglumae (Poaceae: Paniceae). Sida 14: 145-167.