The taxonomic position of Corydalis parviflora Su & Lidén (Papaveraceae), a genetically distinct species: Evidence from cpDNA and nDNA sequences

• We tested the putative hybrid origins of Corydalis parviflora by comparing nuclear (NADPH) and chloroplast DNA sequences.
• C. parviflora is genetically distinct from Corydalis saxicola, Corydalis balansae, and Corydalis racemosa, its proposed parents.
• C. parviflora is not a hybrid and it should be placed in Corydalis sect. Sophorocapnos.
• Chloroplast and single-copy nuclear data may be used in conjunction to test hypotheses of hybrid origins.

The taxonomic position of Corydalis parviflora Su & Lidén, an endemic Chinese herb that grows in limestone crevices, has been uncertain. It was presumed to be a hybrid and had been placed in Corydalis section Thalictrifoliae or section Sophorocapnos. To test whether C. parviflora represents a hybrid of Corydalis saxicola Bunting (section Thalictrifoliae) with Corydalis balansae Prain (section Sophorocapnos) and/or Corydalis racemosa Pers. (section Cheilanthifoliae), we compared cpDNA (rbcL, psbA-trnH, and the trnG intron) and nDNA (NADPH-ferrihemoprotein oxidoreductase) sequences of these taxa and reconstructed phylogenetic trees from 18 Corydalis species and two outgroup species. Corydalis parviflora differs from its putative parents in both cpDNA and nDNA sequences and represented a separate lineage within section Sophorocapnos. These findings demonstrate that C. parviflora is not a hybrid and is more closely related to species in section Sophorocapnos than in section Thalictrifoliae. They also demonstrate that although hybridization is considered a relatively common phenomenon in vascular plants, assumptions of interspecific hybridization that are based on morphological similarities need to be tested through genetic analyses.