First record of Monochoria hastata: a new alien weed of rice in Pakistan.
Monochoria hastata (L.) Solms. of family Pontederiaceae is the first time reported as a new species in the alien weed flora of Pakistan. M. hastata has been found in flooded rice fields, ponds and swampy places in the District Narowal of the Province Punjab, Pakistan. It has been also reported as a weed of rice fields in many countries of South and Southeast Asia and is an aggressive weed that reproduces both sexually (seed) and vegetatively (stolons). The comprehensive morphometric description, preliminary distribution, importance and resemblance with closely related plants species, M. Vagenalis (Burm.f.) C. Presl ex Kunthare presented. At present, this exotic weed is not widespread in Pakistan hence, it is may be possible to eradicate it before it is widely established and difficult to control.