Paspalum distichum (PROSEA)
- Protologue: Syst. Nat. ed. 10, 2: 855 (1759).
- Family: Gramineae
- Chromosome number: 2n= 40, 48, 60
Paspalum paspalodes Scribner (1894).
- Ginger grass, knot grass, (salt-)water couch grass (En)
- Indonesia: rumput italia, asinan (Javanese), lamhani (Sundanese)
- Philippines: malit-kalabaw (Tagalog), bakbaba (Ilokano), gagayut (Wfumo)
- Thailand: ya-sakatnamkhem (northern)
- Vietnam: co' san dôi.
Origin and geographic distribution
A common weed of the tropics, subtropics and warm temperate regions of unknown origin. In Malesia P. distichum probably has been introduced.
Considered as a valuable pasture grass on alluvial flats, P. distichum is used as a fodder and is relished by water buffaloes. On stream banks it is useful as a soil binder. In direct-seeded rice it is a serious weed that grows vigorously under favourable conditions.
Nitrogen concentrations of up to 1.5% have been measured, with Ca and P concentrations of 0.22% and 0.14% respectively. It is moderately palatable.
A stoloniferous perennial, sometimes tufted, with leafy stolons rooting at the nodes, and ascending or erect culms 10-60(-100) cm long. Leaf-sheath usually hairy along the margins; ligule truncate or slightly lobed, 0.5-3 mm long; leaf-blade linear, 6-10(-20) cm × 3-5(-9) mm, attenuate-acute, usually with some white hairs at the immediate base of the ligule, otherwise glabrous. Inflorescence composed of 2 subopposite racemes, each 2-8 cm long; spikelets solitary, the upper ones usually imbricate, oblongoid, 3-4 mm long, with acute apex; lower glume often reduced or absent; upper glume pubescent, sometimes leathery. Caryopsis ovoid, plano-convex, ca. 1.5 mm long.
Flowering is throughout the year. Seeds appear to have a period of dormancy; they germinate best at 20-30 °C. From India obligate apomixis has been reported for P. distichum .
The species closely resembles P. vaginatum Swartz with which it is often confused; P. vaginatum does not extend into temperate regions, has at least two strictly opposite racemes in the inflorescence, and its upper glumes are glabrous.
P. distichum occurs in wet marshlands, swamps, in polluted shallow water, along irrigation ditches, etc., up to 1700 m altitude. It can stand high salinity and tolerates waterlogged conditions and periodic flooding in salt swamps and by tidal waters.
P. distichum can be established by seed or stolons. It requires minimum land preparation and is easily established by placing stolons in holes made in moist soil. The plant remains green throughout the year if growing in water. Light grazing with long rest periods of 80-90 days is recommended since the rooted stolons are sometimes floating. Harrowing of dry surface soils will later help the spreading stolons to root and so form a denser sward. It can be cut and fed to animals, but normally villagers let their animals graze it. Observations suggest that it does not give high DM yields. It can be made into hay but is not suitable for silage.
Genetic resources and breeding
It is unlikely that substantial germplasm collections are being maintained.
P. distichum should be included when selecting for species that are tolerant to saline soils.
- de Koning, R. & Sosef, M.S.M., 1985. The Malesian species of Paspalum (Gramineae). Blumea 30: 295-297.
- Manidool, C., 1989. Natural grassland and native grasses of Thailand [in Thai]. Technical Bulletin No 1301-26-32. Division of Animal Nutrition, Department of Livestock Development, Bangkok. pp. 26-32.
- Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome. pp. 565-568.
- Soerjani, M., Kostermans, A.J.G.H. & Tjitrosoepomo, G. (Editors), 1987. Weeds of rice in Indonesia. Balai Pustaka, Jakarta. pp. 460-461.