Spartina Schreb.
Spartina is a relatively small genus of ca. 15-17 species. All species are salt-tolerant and predominantly occur in saline habitats in America (obviously its center of diversity), Europe and Africa, both coastal and interior. One species, Spartina maritima (Curt.) Fernald is native in Belgium but is long extinct now (probably since 1921; Vanhecke 2006a).
Recent molecular studies have shown that, despite being morphologically very different, Spartina is in fact nested in Sporobolus (Peterson & al. 2014). However, for various reasons this point of view is not always accepted (see e.g. Bortolus & al. 2019).
Several other species of Spartina, all of North American origin, have been recorded in Europe and might be found in Belgium as well (although the number of suitable habitats for Spartina-species is rather restricted in Belgium). Spartina alterniflora Loisel. (syn.: S. brasiliensis Raddi), one of the progenitors of S. townsendii, was formerly introduced for tideland reclamation in the British Isles, southwestern France and northern Spain and was able to naturalize subsequently. It is probably decreasing now. Another North American species, Spartina patens (Aiton) Muhl., was recently found in the British Isles (Anonymus 2006, Stace 2010). It much resembles the southern European native species Spartina versicolor Fabre and might be confused with it. One species, Spartina pectinata, is increasingly cultivated as an ornamental in Europe (Jäger & al. 2008).
Several species of Spartina are reputed environmental weeds. Useful additional information on its invasiveness is provided by the Coastal Conservancy at: www.spartina.org.
1. Upper glume very scabrid on keel, conspicuously awned (awn 3-8 mm long). Leaf margins very scabrid. Racemes often numerous, up to 50. Culms erect, usually much exceeding 150 cm (up to 250 cm tall). Not confined to coastal areas === 1. Spartina pectinata
1. Upper glume glabrous or softly short-hairy, awnless. Leaf margins smooth or slightly scabrous. Racemes fewer, up to 10. Culms often more ascending, usually not exceeding 150 cm. Plants confined to coastal areas === 2
2. Ligule 0,2-0,6 mm. Anthers 4-6 mm, well-filled and dehiscent at maturity. Plant often slender (rarely exceeding 50 cm) with leaves up to 6 mm wide. Inflorescence with up to 5 racemes (native) === S. maritima
2. Ligule 1-2 mm (rarely less). Anthers 5-10 mm, poorly filled and indehiscent (or, more rarely, well-filled and dehiscent) at maturity. Plant usually taller (up to 150 cm) with leaves up to 15 mm wide. Inflorescence with up to 10 racemes === 2. S. townsendii
Literature
Adema F. & Mennema J. (1979) De Nederlandse slijkgrassen. Gorteria 9: 330-334.
Ainouche M.L., Baumel A., Salmon A. & Yannic G. (2004) Hybridization, polyploidy and speciation in Spartina (Poaceae). New Phytologist 161(1): 165-172.
Ainouche M.L., Fortune P.M., Salmon A., Parisod C., Grandbastien M.-A., Fukunaga K., Ricou M. & Misset M.-T. (2009) Hybridization, polyploidy and invasion: lessons from Spartina (Poaceae). Plant Syst. Evol. 273(1-2): 51-61.
Anonymus (2006) Plant records. Watsonia 26(2): 179-195.
Barkworth M.E. (2003) Spartina. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 25: 240-251. Oxford University Press, New York-Oxford.
Baumel A., Ainouche M.L., Bayer R.J., Ainouche A.K. & Misset M.T. (2002) Molecular phylogeny of hybridizing species from the genus Spartina Schreb. (Poaceae). Molecular Phylogenetics and Evolution 22(2): 303-314.
Bortolus A. et al. (2019) Supporting Spartina: Interdisciplinary perspective shows Spartina as a distinct solid genus. Ecology 100(11): e02863. [aivailable online at: https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecy.2863]
Hilu K.W. & Alice L.A. (2001) A phylogeny of Chloridoideae (Poaceae) based on matK sequences. Syst. Bot. 26: 386-405.
Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.
Lambinon J., Delvosalle L., Duvigneaud J. (avec coll. Geerinck D., Lebeau J., Schumacker R. & Vannerom H. (2004) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Cinquième édition. Jardin botanique national de Belgique, Meise: CXXX + 1167 p.
Mobberley D.G. (1956) Taxonomy and distribution of the genus Spartina. Iowa State Coll. J. Sc. 30: 471-574.
Peterson P.M., Romaschenko K., Arrieta Y.H. & Saarela J.M. (2014) A molecular phylogeny and new subgeneric classification of Sporobolus (Poaceae: Chloridoideae: Sporobolinae). Taxon 63(6): 1212-1243.
Saarela J.M. (2012) Taxonomic synopsis of invasive and native Spartina (Poaceae, Chloridoideae) in the Pacific Northwest (British Columbia, Washington and Oregon), including the first report of Spartina ×townsendii for British Columbia, Canada. PhytoKeys 10: 25-82. [available online at: http://www.pensoft.net/journals/phytokeys/issue/10/]
Spicher D. & Joselyn M. (1985) Spartina (Gramineae) in northern California: distribution and taxonomic notes. Madroño 32: 158-167.
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Vanhecke L. (2006a) Spartina maritima. In: Van Landuyt W., Hoste I., Vanhecke L., Van den Bremt P., Vercruysse W. & De Beer D., Atlas van de Flora van Vlaanderen en het Brussels Gewest. Instituut voor natuur- en bosonderzoek, Nationale Plantentuin van België en Flo.Wer: 848.