Echinochloa pyramidalis.

E. pyramidalis, a perennial grass, has decidedly invasive characteristics with its vigorous shoot and rhizome growth and abundant seed production. As an aquatic, it also has the potential to be very damaging to sensitive aquatic habitats. Holm et al. (1979) record it as a major weed in its native area in Nigeria, Swaziland, Sudan and Madagascar. In Guyana, after being introduced and cultivated for some years, it was noticed as a weed in sugar cane in 1982 and increased rapidly to become one of the most troublesome weeds in the aquatic system of the Guyana Sugar Corporation (Bishundial et al., 1997). In Mexico, again after introduction as a fodder grass, it has become widely invasive in wetlands, tending to reduce native wetland species (López Rosas et al., 2010). Apart from its competitive growth, Wells et al. (1986) note its tendency to obstruct water flow. For the USA it is highly ranked as a potential invasive weed of the future (Parker et al., 2007) and it has been identified as a species 'not authorized (for introduction) pending pest risk analysis' (NAPPRA) (USDA-APHIS, 2012).