Melica rigida is a species of grass found in Argentina, Brazil (Santa Catarina, Rio Grande do Sul), and Uruguay.[1]
The species is perennial with short rhizomes. It culms are erected and 20- long while the plant stem is smooth. The leaf-sheaths are scabrous, tubular, closed on one end and are glabrous on surface. The leaf-blades are flat, stiff, and are 3– long by 2– wide. They also have scabrous margins and surface, the later one of which is rough. The eciliate membrane have a ligule which is 0.5– long and have a pubescent surface. The panicle is open, linear, and is 6– long by 1– wide. The main panicle branches are appressed with scaberulous and dominant axis.[2]
It spikelets are elliptic, solitary and are 8– long. Fertile spikelets have pedicels which are curved filiform, and scabrous. They also have 2 fertile florets which are diminished at the apex with its rhachilla internodes being scaberulous. The floret callus is pubescent and have hairs which are 0.1– long. The glumes are dissimilar and are keelless and membranous, with other features being different; Lower glume is obovate, 8- long with an obtuses apex, while the upper one is lanceolate, 4– long and have an acute apex.[2]
Lemma have ciliated margins, scaberulous surface, acute apex with the hairs being long. It fertile lemma is chartaceous, elliptic and is 5.5– long by 2– wide. The species' palea have ciliolated keels, smooth surface and dentated apex. Flowers are fleshy, oblong and truncate. They also grow together, 0.3– long, have 2 lodicules and 3 anthers, the later one of which are 1- long. Fruits are dark brown in colour, have caryopsis and additional pericarp. They also have linear hilum while their size is 2.5– long.[2]
In Brazil, the species is found growing in fields on the elevation of 1000-.[1]