Thesis (Ph.D.)--Chulalongkorn University, 2008

In Thailand, although the grasses subtribe Sorghinae have previously been revision studied, it is still not completed. Hence, the aims of this study were to conduct the taxonomic revision of Sorghinae in three topics. Firstly, molecular phylogeny of closely related genera Chrysopogon and Vetiveria based on nuclear ITS and chloroplast trnL-F genes to clarify taxonomic delimitation of these two genera, the results suggested strongly to include Vetiveria in Chrysopogon. Secondly, anatomical utilization of leaf and culm in classification of genera and species in Sorghinae, the results revealed that micro-structures such as short cells, silica-bodies, macro-hairs, micro-hairs, prickle-hairs, papillae, stomata, shape of sclerenchyma at leaf margin, and vascular bundle arrangement in culm could be used both at generic and specific levels. Finally, taxonomic revision employing morphological character, anatomy and molecular phylogeny, which indicated that as many as 29 species in 7 genera were enumerated in Thailand. Among those, Chrysopogon gryllus (L.) Trin. subsp. gryllus was a new record to Thailand, while 2 new species of Capillipedium were found. In addition, the lectotypification of Andropogon capilliflorus Steud (synonym of Capillipedium parviflorum (R. Br.) Stapf), and Hemisorghum mekongense (A. Camus) C. E. Hubb. was established. Moreover, Andropogon laguroides DC. (Bothriochloa laguroides (DC.) Herter) was selected to be a type species of Andropogon sect. Amphilophis (synonym of Bothriochloa). The outcome from this study will be submitted to Flora of Thailand (Poaceae) targeting to complete in 2009.