Paspalum L.
Paspalum is a large genus of ca. 330 species (Mabberley 2008), predominantly native to the warm-temperate and subtropical regions of the New World. Rather few are native in the Old World (sub-) tropics. Many species are weeds of agricultural fields and have considerably enlarged their native distribution range and occur at present in many regions of the world. The same holds true for several species that are widely grown for turf. None is native in Belgium.
In addition to the species treated in detail below, Paspalum racemosum Lam. (a native of South America) was recorded in a garden in Linkhout in 1977, obviously as a component of a wild flower seed mixture.
1 Inflorescence conjugate with 2 (rarely 3) branches. Spikelets solitary. Decumbent, stoloniferous perennials, rooting at the lower nodes === 2
1 Inflorescence racemose with usually at least 3 branches. Spikelets paired. Erect, caespitose or rhizomatous perennials === 3
2 Upper glume sparsely short pubescent on the back. Spikelets lanceolate, acute to acuminate at apex. Ligule 0,4-2 mm long === Paspalum distichum
2 Upper glume glabrous on the back. Spikelets ovate, obtuse at apex. Ligule 0,2-0,4 mm long === P. notatum
3 Spikelets 2,8-4 mm long, margins long ciliate. Racemes 3-5 === P. dilatatum
3 Spikelets 1,1-1,4 mm long, margins not ciliate. Racemes numerous, up to 50 === P. paniculatum
Literature:
Allen C.M. & Hall D.W. (2003) Paspalum. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 25: 566-599. Oxford University Press, New York-Oxford.
Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.
Webster R.D. (1987) The Australian Paniceae (Poaceae): 322 p. J. Cramer, Berlin and Stuttgart.
Zuloaga F.O. & Morrone O. (2001) 21. Paspalum. In: Flora Fanerogámica Argentina. Fascículo 71. Pro Flora (Conicet), Córdoba: 54 p.
Zuloaga F.O. & Morrone O. (2005) Revisión de las especies de Paspalum para América del sur austral (Argentina, Bolivia, Sur del Brasil, Chile, Paraguay y Uruguay). Monographs in Systematic Botany from the Missouri Botanical Garden 102: VII + 297 p.