Cuscuta (dodder) are parasitic plants that attack many commercial crops and orchards. There are two species in Taiwan; i.e., C. australis R. Brown and C. Japonica Choisy var. farmosana (Hay.) Yunker. In this report we present the work on the host plants and the haustorium of the laucr species. Field studies indicate that at least 36 host plants are attacked by this dodder including fruit trees, naturally occurring woody species, many herbaceous annual and perennial plants. The spiral growth of this dodder uniformly shows the directions to right, counterclockwise. Two types of hyphac including intercellular and intracellular type arc found which variable with host plants. The penetration of the tip of the haustorium is also under the infuence of internal structure of the host. The presence of prehaustorium, brush like structure and granulated cells in the tip of haustorium are a general feature of this dodder.