According to their morphology，palaeobotany，palynology，cytology and anatomy，the genera Stewartia and Hartia are reasonably combined together．This idea is identical with that of Airy-Shaw(1936)，Sealy(1958)and Spongbeng(1974)．A system of Stewartia s．L. on world scale has been newly suggested in this paper．Based on the connate degree of styli，inflorescence type，shape of bracteoles and sepals and their relative length， the genus is divided into two subgenera，five sections．The new system is as follows：
Stewartia Linn．，s．l．
Subg．Ⅰ. Dialystyla(Szysz．)J．Li et Ming：St．ovata(Cavanilles)Weatherby，St．
yunnanensis H．T．Chang．
Subg．Ⅱ．Stewartia：
Sect．1．Racemosae(Wu)J．Li et Ming：St．monadelpha Siebold et Zuccarini，St．sinii
(Wu)Sealy，St．densivillosa(Hu ex H．T．Chang et C. X．Ye)J．Li et Ming，St.
obovata(Chun ex H．T．Chang)J．Li et Ming，St．tonkinensis(Merr．)C．Y．Wu，
St．crassifolia(S．Z．Yan)J．Li et Ming，St.laotica(Gagnep．)J．Li et Ming．
et Ming，St．pseudocamellia Maxim．St．sichuanensis(S.Z.Yan)J．Li et Ming，
St. micrantha(Chun)Sealy，St. calcicola Ming et J．Li
Sect．5．Pteropetiolatae J．Li et Ming：St．cordifolia(Li)J．Li et Ming，St．villosa
Merr．St．medogensis J．Li et Ming，St．pteropetiolata W．C．Cheng.
One new section and one new species are described；two new names，nine new combinations and ten new synonyms are reported． A key to the species is provided to aid in identification．Stewartia s．l. is of the distribution pattern of E． Asia-N． America， originated and is strongly differentiated in S．and SW．China．According to the fossil data，it is suggested that Stewartia s．l．originated in the early Cretaceous,and was widely and continuously distributed in Laurasia before the Tertiary． Influenced by the glaciers and orogenesis，the present distribution pattern of the genus is tormed．