Abstract: The Chinese drug Tien-hwa-fen, as described in the Chinese pharmacopoeia 1977, is the dried root of Trichosanthes kirilowii Maxim. and T. japonica Regel, family Cucurbitaceae. An investigation of the drug market, however, revealed that the drugs under the generel name "Tien-Hwa-fen" involves 17 species of plants belonging to five genera and two families. The results are summarized in the following table.Species marked with asterisks are described in this paper.The morphological and histological characters of the root of 10 commonly occuring species are discribed concisely with illustrations and the more important diagnostic characters are cgmpared in a table.The relations between the morphological and histological characters of the roots and their plant origins are discussed.