Abstract: Investigations have been made on the mode of development and various characteristics of seedling of 203 grass species representing over 76 genera and 22 tribes. The correlation between important characteristics and their main formative conditions in distribution area and habitat were discussed. According to the various developmental forms of the embryo axis and root system, the seedlings of grasses may be divided into three main types: Bambusoid, Festucoid and Panicoid. And according to characteristics of seedling leaves and adventitious roots, these types may be further divided into seven subtypes: True Bambusoid, Oryzoid, Arundinoid, Stipoid, Festucoid, Eragrostoid and True Panicoid. in this study, the different types of seedlings have been found to be associated with other characteristics of embryo and adult plant; and on these grounds, the genera of the Gramineae are grouped into seven corresponding subfamilies: Bambusoideae, Oryzoideae, Arundinoideae, Stipoideae, Festucoideae, Eragrostoideae and Panicoideae.