Tendency on the identification for plant species or varieties

Classification on of plant species or variety was usually based on 4 genetic markers:1)morphological markers;2)cytological markers;3)biochemical markers and 4)molecular markers.In most cases,it was difficult to identify relative species or varieties by morphological markers,as well as cytological markers and biochemical markers.This paper summarized and analyzed these methods above for identifying relative species and varieties,and pointed out that with the development of molecular biology,DNA molecular marker will be used widely for identifying relative species and varieties.