Rostraria cristata (L.) Tsvelev (syn.: Koeleria phleoides (Vill.) Pers., Lophochloa cristata (L.) Hyl., L. phleoides (Vill.) Reichenb., Trisetaria cristata (L.) Kerguélen) (Medit.) – A rare and often ephemeral alien, it was formerly chiefly introduced with wool, currently mostly as rare grain alien (Verloove & Vandenberghe 1995). Recent records have also been associated with tourists and their goods, e.g. for plants found in camping sites. Since 2005 found from time to time as an urban weed in Brussels (Allemeersch 2006). In one of its localities there, in the abandoned railway yard of Josaphat, it persists at least since 2005 (Saintenoy-Simon 2016). As such, increasingly found in the Netherlands as well (Denters 2004; see also: http://www.verspreidingsatlas.nl/5371#). In 2015 found in gravel at railway stations in Châtelet near Charleroi (comm. M. Lannoy) and Haren (Brussels). Also found, in relative abundance, in a campingsite in De Panne where it must have been introduced by backpackers. At least in this locality Rostraria cristata looks well-established. A future, wider naturalization in suitable habitats (dry, thermophilous) is feasible, especially in cities, railway infrastructure and in coastal areas.
Rostraria cristata is sometimes hardly distinguished from Trisetaria panicea (casual alien). The latter has a laxer panicle and is further separated by its larger anthers (0,8-1,6 mm versus 0,2-0,5 mm), glabrous spikelets and lemma awns that are inserted well below apex; see also Clement 2000).
Rostraria cristata itself is a variable species. Spikelets are usually densely pubescent but individuals with glabrous spikelets have also been encountered. The taxonomic value of this character is uncertain.
Selected literature:
Allan D. (2000) Rostraria cristata in Gosport (S. Hants, v.c. 11). BSBI News 84: 43-44. [available online at: http://archive.bsbi.org.uk/BSBINews84.pdf]
Allemeersch L. (2006) Rostraria cristata, een nieuwkomer in het stedelijk milieu? Dumortiera 90: 27. [available online at: http://alienplantsbelgium.be/sites/alienplantsbelgium.be/files/dum90p27....
Clement E.J. (2000) Rostraria cristata (Poaceae) in the British Isles. BSBI News 84: 44-46. [available online at: http://archive.bsbi.org.uk/BSBINews84.pdf]
Denters T. (2004) Stadsplanten. Veldgids voor de stad. Fontaine Uitgevers, ‘s-Graveland: 432 p.
Saintenoy-Simon J. (2016) Groupe Flore Bruxelloise. Rapport des excursions 2014. Adoxa 90/91: 35-72.
Verloove F. & Vandenberghe C. (1995) Nieuwe en interessante voederadventieven voor de Belgische en Noordfranse flora, hoofdzakelijk in 1994. Dumortiera 61-62: 23-45. [available online at: http://alienplantsbelgium.be/sites/alienplantsbelgium.be/files/dum61-62p...