Glyceria striata (Lam.) A.S. Hitchc. (syn.: G. michauxii Kunth, G. nervata (Willd.) Trin.) (N Am.) – A very rare, locally naturalized alien. A population of Glyceria striata was discovered in 2017 in woodland in the Rochefort area. Subsequently four additional populations were found in the same area (Weyembergh 2017). Few years later, in 2020, the species' was noticed to have expanded but only locally (Weyembergh 2021). Most plants are found near to places (hiking tracks, parking places) that are frequently disturbed by visitors. The species was most likely introduced unintentionally this way, probably from nearby localities in northern France.
Out of the alien species of Glyceria currently found in Europe G. striata is the most widespread. It is naturalized and spreading in numerous European countries (see for instance Holub 1980 but also Haeupler 1971, Carlsson 1976, Raabe 1986, Babczynska-Sendek & Sendek 1989, Ganzert & Walentowski 1989, Melzer & Wagner 1991, Gerstberger 1994, Korneck & Schnittler 1994, Stöhr 2000, Georges 2002, Dančák 2002, Kumm 2002, Felzines & Loiseau 2002, Bizot & Parent 2005, Keil 2005, Piwowarski & Bartoszek 2012, Portal 2014, etc.). It mostly resembles Glyceria canadensis (both belong to section Striatae G.L. Church) but is characterised by smaller spikelets (2-4 mm long, 1,3-2,5 mm wide), smaller lemmas (1.2-1.8 mm long), smaller lower glumes (0,4-0,9 mm long), etc. It is usually found in damp woodlands (clearings, by paths, etc.). In general habit it more looks like a species of Poa than Glyceria and, as a consequence, might pass unrecorded. Glyceria striata occurs in several localities in northern France (near Béthune and Maubeuge), relatively close to the Belgian frontiers (see also Georges 2002). It should be looked for in other places in the southernmost parts of Belgium.
Glyceria striata is a variable species and American authors formerly distinguished a western and eastern variant, respectively var. stricta (Scribn.) Fern. and var. striata. However, the variation appears to be continuous and no infraspecific taxa were accepted in recent American accounts of the genus (e.g. Barkworth & Anderton 2007). Portal (2014), on the contrary, critically revised this complex and concluded that several subspecies can be accepted. In addition to subsp. neogaea (Steud.) Portal (syn.: var. stricta) he described a new subspecies (subsp. difformis Portal) which is in fact ecologically and morphologically very distinct. It is the latter that behaves as an invasive species in France and it is this taxon that has been recorded in Belgium as well (Weyembergh 2017).
Selected literature
Babczynska-Sendek B. & Sendek A. (1989) Glyceria striata (Lam.) Hitchcock - nowy gatunek we florze Polski. Fragm. Florist. Geobot. 34: 75-80.
Barkworth M.E. & Anderton L.K. (2007) Glyceria. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 24: 68-88. Oxford University Press, New York-Oxford.
Bizot A. & Parent G.H. (2005) Trois plantes américaines du Nord-Est de la France: 1. Carex vulpinoidea Michx., 2. Glyceria striata (Lam.) Hitchcock, 3. Scirpus atrovirens Willd. Bull. Soc. Hist. Nat. Ard. 94: 24-34.
Carlsson R. (1976) Glyceria striata funnen i Sverige. Svensk Bot. Tidskr. 70: 57-60.
Dančák M. (2002) Glyceria striata – a new alien grass species in the flora of the Czech Republic. Preslia 74: 281-289. [available online at: http://www.preslia.cz/P023CDan.pdf]
Felzines J.-C. & Loiseau J.-E. (2002) Cyperus reflexus Vahl et Glyceria striatus (Lam.) A.S. Hitch., deux adventices en cours de naturalisation dans la vallée de la Dordogne moyenne. Monde Pl. 478: 9-11.
Ganzert C. & Walentowski H. (1989) Glyceria striata (Lam.) Hitchc. – eine neue Graminee in der Flora Bayerns. Ber. Bayer. Bot. Ges. 60: 191-194.
Georges N. (2002) Glyceria striata (Lamarck) A. Hitchcock, une nouvelle poacée pour la flore de Lorraine. Monde Pl. 477: 15-18.
Gerstberger P. (1994) Die Neophyten Glyceria striata und Scirpus atrovirens im Rheinischen Schiefergebirge bei Oberwinter. Decheniana 147: 44-48.
Haeupler H. (1971) Glyceria striata (Lam.) Hitchc. - ein Neubürger in Deutschlands Gramineenflora. Gött. Florist. Rundbr. 5: 63-68.
Holub J. (1980) Glyceria. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 5. Cambridge University Press, Cambridge: 180-181.
Keil P. (2005) Ein Vorkommen von Glyceria striata (Lam.) Hitchc. in Wuppertal-Dornap. Natur und Heimat 65: 61-63.
Korneck D. & Schnittler M. (1994) Glyceria striata und Scirpus atrovirens im Rheinland. Flor. Rundbr. 28: 29-36.
Kumm V. (2002) Ein Vorkommen von Glyceria striata im Springbruch bei Potsdam. Verh. Bot. Ver. Berlin Brandenburg 135: 11-16.
Melzer H. & Wagner S. (1991) Glyceria striata (Lam.) A.S. Hitchc., das gestreifte Schwadengras – neu für Oberösterreich. Linzer biol. Beitr. 23: 251-255.
Piwowarski B. & Bartoszek W. (2012) The occurrence of Glyceria striata (Lam.) Hitchc. in Europe and the new localities of the species in Poland. Acta Societatis Botanicorum Poloniae 81(2): 87-92. [available online at: https://pbsociety.org.pl/journals/index.php/asbp/article/view/asbp.2012....
Portal R. (2014) Glyceria, Puccinellia, Pseudosclerochloa. France, pays voisins et Afrique du Nord. Vals-près-Le Puy: 149 p.
Raabe U. (1986) Der Gestreifte Schwaden, Glyceria striata (Lam.) Hitchcock, bei Bad Rothenfelde, Kreis Osnabrück. Flor. Rundbr. 19(2): 85-87.
Stöhr O. (2000) Glyceria striata (LAM.) HlTCHC. - neu für Salzburg sowie weitere interessante Gefaßpflanzenfunde für dieses Bundesland. Linzer biol. Beitr. 32(1): 329-340. [available online at: http://www.zobodat.at/pdf/LBB_0032_1_0329-0340.pdf]
Vernier F. (2015) Glyceria striata (Lam.) A.S. Hitchc. subsp. difformis Portal, la glycérie striée, une obsidionale invasive potentielle en Lorraine. Les Nouvelles Archives de la Flore jurassienne et du nord-est de la France 13: 99-104.
Weyembergh G. (2017) Glyceria striata (Lam.) A.S. Hitchc. subsp. difformis Portal, nouvelle espèce pour la flore belge. Adoxa 93/94: 1-9.
Weyembergh G. (2021) A propos de Glyceria striata, néophyte naturalisé à Fèsches. Les Barbouillons 314: 37-43. [available online at: https://naturalistesdelahautelesse.be/Barbouillons/Les_Barbouillons_314_...