Brachypodium distachyon (L.) Beauv. (syn.: Bromus distachyos L., Trachynia distachya (L.) Link) (Medit., W-As., Macaronesia) – Formerly naturalised on rocky, schistose soil between Sougnez and Aywaille, at least between 1824 and 1888. Surely long gone by now. Elsewhere a very rare, much decreasing and always ephemeral alien. Formerly introduced with wool in the Vesdre valley (mostly in the 1940’s and 1950’s) and with grain in a few, widely scattered localities. By far most records are from the 19th century. Apparently last seen in the wild on a dump between Andrimont and Henri-Chapelle in 1956.
Since 2008 also recorded as a weed in containers with imported olive trees in plant nurseries (Hoste & al. 2009).
Recent cytogenetic and molecular studies detected three cytotypes in Brachypodium distachyon sensu lato. These are indicative of major speciation processes within this complex and allow their taxonomic separation into three distinct species. The name B. distachyon was kept for the 2=10 cytotype while two novel species were described: B. stacei and B. hybridum for, respectively, the 2n=20 and 2n=30 cytotype (Catalán & al. 2012). It is unclear to which microspecies the Belgian plants belong.
Catalán P., Müller J., Hasterok R., Jenkins G., Mur L.A.J., Langdon T., Betekhtin A., Siwinska D., Pimentel M. & López-Alvarez D. (2012) Evolution and taxonomic split of the model grass Brachypodium distachyon. Ann. Bot. 109: 385-405. [available online at: http://aob.oxfordjournals.org/content/109/2/385.full.pdf+html]
Hoste I., Verloove F., Nagels C., Andriessen L. & Lambinon J. (2009) De adventievenflora van in België ingevoerde mediterrane containerplanten. Dumortiera 97: 1-16.