山兰（学名：Oreorchis patens）为兰科山兰属下的一个种。

Oreorchis patens is a species of orchid native to eastern Asia. It is known from Japan, Korea, Russian Far East (Kamchatka, Primorye, Sakhalin, Kuril Islands), China (Gansu, Guizhou, Heilongjiang, Henan, Hunan, Jiangxi, Jilin, Liaoning, Sichuan, ******, Yunnan).