大赖草（学名：Leymus racemosus）为菊科赖草属下的一个种。

Leymus racemosus is a species of perennial wild rye known by the common name mammoth wild rye. It is native to southeastern and eastern Europe, Middle Asia, Caucasus, Siberia, China, Mongolia, New Zealand, and parts of North America. Culms are 50–100 cm long, and 10–12 mm in diameter.