Study on diversity of endosperm cells in seeds of Leymus Leymus paucispiculus,a New Species of Poaceae from China Seed Dormancy and Hormone Control of Germination in Leymus Hochst Taxonomic notes on the genus Leymus Hochst.(Poaceae) from China Two new varieties of Leymus Hochst. (Poaceae) from Xinjiang, China