Lachnagrostis Trin.
Lachnagrostis is a genus with 20-30 species, all originally native in the southern hemisphere. Its center of diversity obviously lies in Australasia (mainly New Zealand where many endemic species occur; Edgar 1995). Some additional species, of uncertain relationship, originate in South America, Malaysia and South Africa. Lachnagrostis is a segregate of Agrostis and its generic status has become widely accepted (e.g. Harvey 2007, Mabberley 2008, Jacobs & Brown 2009). Both genera are told apart on rather subtle characters of lemma epidermis (a discernible pattern of low relief in Lachnagrostis vs. a well-developed raised pattern in Agrostis). Lachnagrostis usually also has a well-developed rachilla extension, longer paleas and a panicle that easily detach at maturity. However, both genera have species that resemble one another in one of these features (Harvey 2007; compare with Quintanar & al. 2007). According to Saarela & al. (2017) Agrostis, Lachnagrostis and Polypogon form a clade and species of each are variously intermixed in plastid and nuclear ribosomal trees.
At least one species, Lachnagrostis filiformis, is fairly weedy and now widely occurs beyond its original distribution range. It has repeatedly been recorded in Belgium as well.
Literature:
Brown A.J. (2006) The taxonomic status of Lachnagrostis scabra, L. aequata and other related grasses in Australia (Poaceae). Muelleria 24: 111-136.
Brown A.J. (2008) New Lachnagrostis taxa from South Australia and South-west Victoria (Poaceae). Muelleria 26: 21-44.
Edgar E. (1995) New Zealand species of Deyeuxia P. Beauv. and Lachnagrostis Trin. (Gramineae: Aveneae). New Zealand J. Bot. 33(1): 1-33. [available online at: http://www.tandfonline.com/doi/abs/10.1080/0028825X.1995.10412940#.UneTt1MdMkQ]
Edgar E. & Forde M.B. (1991) Agrostis L. in New Zealand. New Zealand J. Bot. 29: 139-161. [available online at: http://www.tandfonline.com/doi/abs/10.1080/0028825X.1991.10416717#.UnjKm8FkDIU]
Harvey M.J. (2007) Lachnagrostis. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 24: 694-696. Oxford University Press, New York-Oxford.
Jacobs S.W.L. (2001) The genus Lachnagrostis (Gramineae) in Australia. Telopea 9(3): 439-448. [available online at: http://www.rbgsyd.nsw.gov.au/__data/assets/pdf_file/0018/72810/Tel9Jac439.pdf]
Jacobs S.W.L. & Brown A.J. (2009) Lachnagrostis. In: Wilson A. (ed.), Flora of Australia, vol. 44A, Poaceae 2: 174-190. Australian Biological Resources Study, Canberra.
Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.
Quintanar A., Castroviejo S. & Catalán P. (2007) Phylogeny of the tribe Aveneae (Pooideae, Poaceae) inferred from plastid trnT-F and nuclear ITS sequences. Am. J. Bot. 94(9): 1554-1569. [available online at: http://www.amjbot.org/content/94/9/1554.full]
Rugolo de Agrasar Z.E. (1982) Revalidación del género Bromidium Nees et Mayen emend. Pilger (Gramineae). Darwiniana 24(1-4): 187-216.
Ryves T.B., Clement E.J. & Foster M.C. (1996) Alien grasses of the British Isles. BSBI, London: XX + 181 p.
Saarela J.M., Bull R.D., Paradis M.J., Ebata S.N., Peterson P.M., Soreng R.J. & Paszko B. (2017) Molecular phylogenetics of cool-season grasses in the subtribes Agrostidinae, Anthoxanthinae, Aveninae, Brizinae, Calothecinae, Koeleriinae and
Phalaridinae (Poaceae, Pooideae, Poeae, Poeae chloroplast group 1). PhytoKeys 87: 1–139. [available online at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5672130/pdf/phytokeys-87-00...
Vickery J.W. (1941) A revision of the Australian species of Agrostis Linn. Contr. New South Wales Natl. Herb. 1: 101-119.