Ischaemum rugosum

About

Ischaemum rugosum, also known as saramollagrass, is a flowering plant belonging to the grass family Poaceae in the genus Ischaemum, and is native to tropical and temperate regions of Asia, growing in marshes and other wet habitats. It is a vigorous annual, and is an invasive species in South America and Madagascar. It reaches heights of up to 1 m and is primarily recognized by the ridged surface of its sessile spikelet's lower glume. Despite its historic importance as fodder in Asia, the grass has become a major weed in mid-latitude rice paddies throughout Asia and South America.

Summary from Wikipedia