Echinochloa oryzoides (Ard.) Fritsch (Na-do-non-pee), was found at paddy fields of Jeonranamdo on a large scale after a first discovery at Masan, Kyeongsangnamdo. This species was not easily distinguished from rice before flowering at the paddy field because of a similar morphology to rice. It is, however, distinguished from other species of the Korean Echinochloa by reliable morphological characters such as horizontal or drooping panicles at maturity, lower glumes with usually 1/4-2/5 as long as the spikelets, awned lower lemmas, and the number of chromosomes, 2n = 54. Echinochloa oryzicola (Vasinger) Vasinger was distinguished from E. oryzoides by erect panicles, lower glumes with at least 1/2 as long as the spikelets, and the number of chromosomes, 2n = 36.