Agrostis exarata Trin. (N-Am., As.) – Found once as a grass seed impurity on a sand-raised site (road works) in Diest in 1990 (along with Navarretia squarrosa). Reported as abundantly self-seeding but eventually gone in 1992.
Initially mistaken for xAgropogon lutosus (Poir.) P. Fourn. (syn.: xA. littoralis (Sm.) C.E. Hubbard), an intergeneric hybrid between Agrostis stolonifera and Polypogon monspeliensis (Verloove & Lambinon 2008). Agrostis exarata may have been overlooked since it also somehow resembles Apera interrupta. It seems to be a regular grass seed impurity in several parts of Europe, for instance in the British Isles (Ryves & al. 1996) and in Scandinavia (Stenberg 1994).
Agrostis exarata is a more or less anomalous species in Agrostis, for instance on behalf of its distinctly awned glumes. It seems to be more closely related to species of Polypogon, rather than to other species of Agrostis (Saarela & al. 2010). Additional molecular studies should elucidate its position.
Selected literature:
Ryves T.B., Clement E.J. & Foster M.C. (1996) Alien grasses of the British Isles. BSBI, London: XX + 181 p.
Saarela J.M., Liu Q., Peterson P.M., Soreng R.J. & Paszko B. (2010) Phylogenetics of the Grass ‘Aveneae-Type Plastid DNA Clade’ (Poaceae: Pooideae, Poeae) Based on Plastid and Nuclear Ribosomal DNA Sequence Data. In: Seberg O. & al. (eds.), Diversity, phylogeny, and evolution in the Monocotyledons. Aarhus, Denmark: Aarhus University Press: 557-587.
Stenberg L. (1994) Dikesven, Agrostis exarata, i Norrbotten – första fyndet i Norden. Svensk Bot. Tidskr. 88: 353-355.
Verloove F. & Lambinon J. (2008) Neophytes in Belgium: corrections and adjustments. Syst. Geogr. Pl. 78: 63-79.