Cyperus eragrostis Lam. (syn.: C. vegetus Willd.) (Am.) – A rare but much increasing alien. Formerly frequently introduced as a wool alien in the Vesdre valley, at least between 1896 and 1959 (but probably always ephemeral). Elsewhere very exceptional, for instance in the port of Antwerpen in 1911 and 1912 or on a coal mine heap in Bernissart in 1955. In the past decades also recorded as a grain alien or as an escape from cultivation. Perhaps sometimes introduced unintentionally by migrating birds (probably from the species’ secondary area in southwestern Europe). Obviously increasing from the 1990’s onwards in many parts of Flanders, often in nature-like habitats (pond margins, riverbanks or marshes) and locally becoming naturalised (Verloove 2006a). Sometimes behaving like a troublesome weed in gardens or plant nurseries. Recent records are also available now from Wallonia, at least from the province of Wallonia (comm. P. Dupriez 2010). Invasive behaviour of Cyperus eragrostis in Belgium cannot be excluded. It was recently recorded in or near several nature reserves, for instance in Heusden (Damvallei), Wingene (Gulke Putten), ....
Additional information on the invasive behaviour of Cyperus eragrostis in Belgium is available at: http://ias.biodiversity.be/species/show/115.
Selected literature
Dakskobler I. & Vreš B. (2009) Cyperus eragrostis Lam. – a new adventitious species in the flora of Slovenia. Hacquetia 8(1): 79-90.
Denton M.F. (1978) The Luzulae group of Cyperus (Cyperaceae). Contr. Univ. Michigan Herb. 11: 197-271.
Henrion E. (2007) Deux espèces de Cyperus découvertes simultanément. Adoxa 57: 7-8.
Mang F.W.C. (1984) Pflanzen, von denen in der mitteleuropaischen Literatur selten oder gar keine Abbildungen zu finden sind. Folge 18: Cyperus eragrostis Lam. Gött. Flor Rundbr. 18(3-4): 101-104.
Petrik P. (2003) Cyperus eragrostis: a new alien species for the Czech flora and the history of its invasion of Europe. Preslia 75(1): 17-28.
Verloove F. (2003) Graanadventieven nieuw voor de Belgische flora, hoofdzakelijk in 1999 en 2000. Dumortiera 80: 45-53.