Background: An unknown Sedum was found from the limestone region in Taiwan. After a detailed comparison with other congeners in Taiwan and neighboring countries, we identified this plant as a new species.
Results: This new taxon resembles S. nokoense Yamamoto, S. alfredii Hance, and S. uniflorum Hook. & Arn. subsp. oryzifolium (Makino) H. Ohba, but differs in leaf shape, sepal morphology, and seed testa micro-morphology. Ecologically, this new taxon occurs exclusively on limestone, while S. nokoense and S. alfredii grow in non-limestone areas and S. uniflorum subsp. oryzifolium is only found on sandy seashores.
Conclusions: Sedum tarokoense H.W. Lin & J.C. Wang is described as a new species. We provide a description, line drawing, and distribution map, as well as photograph, a key and a table to distinguish S. tarokoense from its related species.
Keywords: Crassulaceae; Ecological isolation; Sedum; Sedum tarokoense; Seed testa; Taiwan.