Abstract
This investigation was simultaneously conducted with the previous one in the same creeks.
Waterhyacinth [Eichhornia crassipes (Mart.) Solms] distributed throughout Chikugo and Saga Plains, and grew in 40% investigated creeks. Knotgress (Paspalum distichum L.) was found chiefly in creeks of Saga Pl., and its frequency was 32%. On the other hand, its hairly subspecies (Paspalum sp.) was found chiefly in those of Chikugo Pl., and the frequency was 22%. Parrotfeather (Myriophyllum brasiliense Camb.) infested creeks of a few towns and cities of Chikugo Pl., but it was also found in several localized ones of Saga Pl. Its frequency was only 5%. Almost all other weeds grew and spread throughout the area, but their frequencies were 20% (frogbit [Hydrocharis dubia (Bl.) Backer]) or less.
