Textual Research on Yang Tong (杨桐，Adinandra millettii), Hai Tong (海桐，Pittosporum tobira) and Chai Tong（拆桐）

Yang Tong is a kind of raw material of plant dyestuff. For people who lived in south of Yangtze River, it is a tradition that they use the leaves of Yang Tong to dye the rice around the Cold Food Day and the Tombsweeping Day. Hai Tong is a famous foliage plant. In Ming dynasty, Hai Tong was often confused with Shan Gong (山矾，Symplocos sumuntia). But in Song Dynasty, Shan Gong means the other plant. Actually, the so called bark of Hai Tong is the bark of Ci Tong (Erythrina variegata), and has nothing to do with Hai Tong. Chou Wutong (Clerodendrum trichotomum) has a long florescence and a large inflorescence, which is one of the famous garden plants. Hutong, namely Huyang（Populus euphratica ）, came from western regions. The resin of Hutong has medicinal values. Chai Tong is fabricated from Liu Yong’s Ci, and the so called flower of Chai Tong is just the flower of Pao Tong (Paulownia).