Notholirion campanulatum is co-specific with N. bulbuliferum (Liliaceae) based on morphology and molecular data

Notholirion campanulatum and N. bulbuliferum are parapatrically distributed in the Qinghai-Tibetan Plateau and adjacent regions, however, their relationship has been controversial for a long time. In this study, six morphological characters including colour of corolla/ovary/bulblet, corolla shape, tepal size, and pollen form, together with nuclear ITS and four cpDNA markers (matK, ndhA, ndhG-I, and petL-G) were selected to perform a comprehensive analysis on 23 populations. Our results indicate that morphological characters of N. campanulatum and N. bulbuliferum are congruent with each other, and the phylogenetic analysis revealed that N. campanulatum closely nested with N. bulbuliferum. Therefore, we propose that these two species should be regarded as synonyms.