Abstract
The species delimitation of Triplostegia has been controversy and traditionally includes two species: T. glandulifera and T. grandiflora. These two taxa differs in some morphological characters on leaves, size of corollas, and achene involucel apex. A recent study proposed to merge these two species into a single taxon, T. glandulifera, while the phylogenetic and morphological evidence suggests that this genus consists of three distinct species, including an undescribed species that is distributed in the Hengduan Mountains Region and east Himalaya. Following the phylogenetic and morphological thesis, the authors describe and illustrate this new species: Triplostegia alpina. This taxon is characterized by a brown main taproot with fine roots and one to three more slender white glabrous lateral taproots, petiolate and serrated leaves, corollas 1.1–2.2 mm, achene involucel apex in purple and slightly hooked, which are distinctive from its two congeners. The study highlight the diagnostic role of taproot, leaf, corolla, and achene involucel in delimiting Triplostegia species.