Annual herb, stoloniferous and with discrete flowers in inflorescences similar to small spikes.
Scientific name: Paspalum paspalodes (Michx.) Scribn.
Common names: knotgrass, ditch-grass, jointgrass, water couch, wiregrass, mercer grass
Family: Poaceae (Gramineae)
Status in Portugal: invasive species (listed in the Decreto-Lei nº 92/2019, 10 july).
Risk Assessment score: 34 | Value obtained according to a protocol adapted from the Australian Weed Risk Assessment (Pheloung et al. 1999), by Morais et al. (2017), according to which values above 13 mean that the species has risk of having invasive behavior in the Portuguese territory | Updated on 30/09/2017.
Synonymy: Digitaria disticha Fiori et Paol., Paspalum distichum L., Paspalum distichum auct., non L.
Last update: 11/07/2021
Native distribution area
Africa, South and North America.
Distribution in Portugal
Mainland Portugal (Minho, Trás-os-Montes, Douro Litoral, Beira Litoral, Beira Alta, Estremadura, Ribatejo, Alto Alentejo, Baixo Alentejo, Algarve), Azores archipelago (all islands), Madeira archipelago (Madeira Island).
Geographic areas where there are records of Paspalum paspalodes
Other places where the species is invasive
Europe (Spain, Italy, Turkey, Albania, Bulgaria, France, Greece, Macedonia, Romania, United Kingdom, Ukraine), Australia, New Zealand.
Introduction reasons
Fodder for animals.
Preferential invasion environments
Humid places, like banks of watercourses, crop fields or rice fields – both in natural environments and with human influence.
It tolerates intensive grazing and fire, but it needs water to recuperate.
It does not tolerate frost well.
