The sunflower family, Asteraceae is one of the largest families of flowering plants in the world. It is widely distributed throughout the world with the most diverse in the temperate regions. The members of the family grow in a broad range of habitats but mainly found in the open area. There are approximately 260 species in Thailand. Many species are of economic and medicinal values, while some species are listed in the checklist of invasive alien species. The invasion by alien species is one of the most leading causes of the biodiversity lost, especially for native species. Therefore, the study on diversity and taxonomic revision of the family in Thailand are needed in order to define the native and alien species and also their conservation status. Both alien and endemic species are important for the biodiversity and conservation approaches. Besides that, biological information for these plants, e.g. physiology, seed dormancy and germination, distribution pattern, invasion mechanism, are required for controlling and management of the alien species as well as conservation of the endemic species.