This is Panicum paludosum Roxb., a grass usually found in sub aquatic habitats like fallow rice fields, submerged and waterlogged areas, marshy or muddy pools, etc. It can be easily identified at a distance because of the stiff and angular arrangement of the branches of the panicle. The lowest branches are almost horizontal when the inflorescene is completely mature. The whole panicle looks like a pyramid. The spikelets are also longer and slender than many of the other Panicums. While collecting grasses, also try to see the nature of the root system and the presence/ absence of rhizomes, stolons, etc. or other characters like sponginess of stems, stolons or basal leaf sheaths, especially in semi aquatic habitat.