A taxonomic re‐assessment in the Chinese Bupleurum (Apiaceae): Insights from morphology, nuclear ribosomal internal transcribed spacer, and chloroplast (trnH‐psbA, matK) sequences

Abstract

As one of the big genera in Apiaceae, Bupleurum L. has received considerable attention from plant taxonomists. Nevertheless, there are still many gaps in our knowledge of this genus, especially of those species endemic to China that have often been excluded from previous studies. In spite of a few recent studies on the phylogeny and classification of the Chinese Bupleurum, the most essential problem of species delimitation still remains unresolved. We re‐evaluate the taxonomy of the Chinese Bupleurum using morphological and molecular evidence. Careful observations of living plants growing the field and herbarium specimens were made to understand the morphological variation and to ensure species identification for the molecular analysis. Phylogenetic analyses were carried out on sequence data of nuclear ribosomal internal transcribed spacer (nrITS), trnH‐psbA, and matK, using parsimony and Bayesian approaches to evaluate species relationships. Analyses of both nrITS and combined datasets of the three regions revealed the following results: (i) the Chinese Bupleurum species were divided into two major lineages; and (ii) most species were well defined, but some traditional inter‐ and infraspecific relationships were not supported. Our results, along with the results of previous works support that the Chinese Bupleurum species were derived from two different lineages and should be placed in Neves and Watson's subgenus Bupleurum. Our detailed taxonomic re‐assessment of several Chinese species resulted in new taxonomic recombinations with rank changes for three species: Bupleurum tenerum, B. amplexicaule, and B. franchetii; new combination for one variety, B. smithii var. flaviflorum; and the description of one variety and one species, B. stenophyllum var. leiocarpum and B. sikangense.

<I>Bupleurum dracaenoides</I> (Subgenus <I>Bupleurum</I>, Apiaceae): a New Shrubby Species from Southwestern China

“…The topologies obtained are similar to those published byWang et al (2008) andWang et al (2011). Bupleurum dracaenoides falls within the clade A representing the subgenus Bupleurum and belongs to a small subclade C that includes B. polyclonum Y. Li & S. L. Pan, B. candollei Wall.…”

“…The sequences from the Blast search and recently published datasets pertaining to Bupleurum phylogeny (Neves and Watson 2004;Yang et al 2007;Wang et al 2008;Wang et al 2011) were used in this study to determine the taxonomic position of B. dracaenoides. In total, 74 DNA sequences (73 of them were downloaded from the GenBank database), including outgroups (Anginon paniculatum (Thunb.)…”

“…Morphologically, it is distinguished from other members of the family by its simple leaves and conspicuous bracts and bracteoles. Molecular analyses have supported Bupleurum as a monophyletic group (Neves and Watson 2004;Wang et al 2008;Wang et al 2011), but its intrageneric classification remains controversial. Moreover, some species (e.g.…”

“…ex DC.) are notoriously difficult to identify due to their broad intraspecific morphological variation (Neves and Watson 2004;Sheh and Watson 2005;Wang et al 2011). Several infrageneric classiðcation systems for Bupleurum have been proposed by European taxonomists, but none has been widely accepted (Drude 1898;Calestani 1905;Wolff 1910;CerceauLarrival 1962;Tutin 1968;Cauwet-Marc 1976).…”

“…Sheh and Watson (2005) reviewed the Chinese Bupleurum for the Flora of China and recognized 42 species (22 of which are native). Based on morphological and molecular evidence, Wang et al (2011) re-examined the taxonomy of Bupleurum from China, and in their study they described one new species and one new variety, raised three varieties to species, and proposed new combinations for one variety.…”