臺灣民間葉用植物紅乳草，主要用於治痢疾與腸炎。一般文獻記載其原植物均指大戟科之Euphorb io thymifolio L.經市場品之調查除此種外另有E. chamaesyce L .及E.mokjno, Hay.且在台南市所購得者以E. chomaesyce L.為主。文獻的混淆，三種植物的相近習性和採藥者的缺乏深究有以至之。
植物性狀、果實、種子特徵及內部構造均有助於鑑別此三種植物和藥材。 This paper deals with the pharmacognostical study on the crude drug " Hong- zu- tsao". Since it was first recorded in the " KOYO TAIWAN MINKAN YAKU SHOK- UBUTSU" by S. Sasaki, it is a very popular folk medicinal plant in Taiwan. The herb is used for curing cartar and intestinal disorder. The origin of this crude drug, "Hong-zu-tsao", had been recognized as Euphorbia thymifolia L. by many authors when they deal with Taiwan medicinal plants.
In this study, it was found that the "Hong-zu-tsao" in Tainan market were from three kinds of Euphorbia plant, namely E. chamaesyce L., E. makinoi Hay., and E. thymifolia L.
It is very easy to distinguish each species by the morphology of fruit and seed ; the anatomy of stem, and the quite conspicuous difference in habit.