Paspalum distichum auct. non Linn.
Creeping stoloniferous perennial; culms 6-50 cm high. Leaf-blades 5-20 cm long, 184.108.40.206 mm wide. Inflorescence composed of 2(4) conjugate racemes, each raceme 1.5-7 cm long, the spikelets single in 2 rows on a flattened rhachis 1-2 mm wide. Spikelets ovate, 2.5-3.5 mm long, plano-convex, relatively plump, pale-green; lower glume often present as a small scale; upper glume appressed-puberulent, herbaceous, with a distinct mid-vein; lower lemma similar but glabrous: upper lemma smooth, pallid at maturity.
Fl. & Fr. Per.: April-May and again August-September.
Type locality: South Carolina, U.S.A.
Distribution: Pakistan (Sind, Punjab, N.W.F.P. & Kashmir); tropics and sub-tropics throughout the world.
Paspalum paspalodes closely resembles the more tropical Paspalum vaginatum Sw. The latter can be recognised by its narrowly ovate-elliptic spikelets, the papery upper glume and lower lemma, and the glabrous upper glume.
The type sheet of Paspalum distichum Linn. bears pieces of two different species. One is Paspalum paspalodes, to which the name “Paspalum distichum” has universally been applied; and Paspalum vaginatum, beside which the faded inscription “Br” indicates that this was the plant collected by Browne. In Sp. Pl., ed. 2, 1:82. 1762, Linnaeus gave the locality of Paspalum distichum as Jamaica, and as Browne collected in Jamaica it appears that the specimen known as Paspalum vaginatum is in fact the true type of Paspalum distichum. The fading of the inscription and the later addition of other material to this sheet are the source of the present nomenclatural confusion. Our species can no longer be called Paspalum distichum, but whether Paspalum vaginatum should be renamed Paspalum distichum is questionable. Clayton (Fl. Trop. E. Afr., Gram. part 3, in press) maintains that to start switching the names of two very similar species at this late stage will cause endless unnecessary confusion. This is a valid point of view resulting in Paspalum distichum Linn. being abandoned altogether as a nomen confusum.
Paspalum paspalodes provides good pasturage, especially on alluvial flats. Known as Knotgrass (in North America) it occurs as a garden weed, along ditches and irrigation channels, as a weed in rice-fields, and is gregarious in swampy places.