In several recent pictorial guides on Taiwanese wildflowers and medicinal plants, color photographs of unknown Acmella species with radiate capitula were erroneously identified as Acmella paniculata or its synonyms, despite this plant's having discoid capitula. As nearly all books attribute medicinal properties to these Acmella, it is imperative to clarify their taxonomy. In this article we document the occurrence of five species of Acmella in Taiwan, two with radiate capitula that were not reported for the flora of this island before, namely: A. brachyglossa and A. ciliata. Detailed description and color photographs and chromosome cytology of all five species of Acmella are provided to aid in identification.