Melica arzivencoi is a grass species in the family Poaceae that is endemic to Brazil where it can be found in Rio Grande do Sul.[1] It was described by Valls and Barcellos in 1973.[2]
The species is bisexual, cespitose, perennial and is rhizomatous. The culms are long and about thick. They are also erect, decumbent, and scabrous at the same time. Leaf-sheaths are closed and are both glabrous and scabrous. The leaf-blades on the other hand are acute and are 2- long and 1.5- wide. They are also flat, linear and have an adaxial bottom which is hispid and tipped. Panicles are erect, narrow and dense. They can either be 6- long or 7-. Branches are long and are erect with villous pedicels which are curved as well. Spikelets are 3.5- in length but could exceed up to . When young, they are bright violet in colour, and carry 1-2 bisexual florets by maturity. The glumes are acute, glabrous, hyaline, membranous, and lanceolated at the same time and have 3-5 veines. Lemma is lanceolated as well and is 3- long. Fruits are about long are in diameter and obovoid as well.[1]
It grows in grassy, woody landscapes, and on rocks at elevations of . In some cases they require moisture that should be at 900-. Flowers bloom from December to February.[1]