Abstract: A new species of Leymus in Qinghai, China is reported, and it’s called L. oblongolenmatus L. Zhi et L. B. Cai. The main characters are described as follows: Perennial herbs. Stems are erect and glabrous, few and scattered, 60~90 cm. tall. tough leaf-sheath, membranaceous on margins, longer or shorter than internodes, membranaceous ligules; Leaf blades involute on margins. Spikes are erect, conferted and flavor-green, 10~15 cm. long, 5~15 mm. wide. tough rachis, each node of rachis are with 3~4 spikelets, with 3~6 florets. Glumes lanceolate, 4~7 mm long and three to five-nerved, membranaceous on margins. Lemmas prolate spheroidal and lanceolate, obscurely three-nerved, with sparse short-pilose on the back. Anther flavescent, 4~5 mm. long. This species is similar to L. paboahus.

Key words: Leymus, L. oblongolemmatus, new species, Qinghai, China