Phylogeny and taxonomy of Cinnamomum (Lauraceae)

Abstract

Taxonomy of Cinnamomum Schaeff. of Lauraceae remains problematic because recent phylogenetic studies have suggested that this genus is not monophyletic. In this study, we assembled three sequence matrices including plastomes (datamatrix I), nrITS sequences alone (datamatrix II), and nrITS plus plastid psbA-trnH sequences (datamatrix III) of the Cinnamomum-Ocotea complex of Lauraceae and conducted a new phylogenetic study with thusfar the most extensive species sampling of the Cinnamomum-Ocotea group. We determined that the Old World Cinnamomum is diphyletic: sect. Camphora Meisn. is sister to Sassafras J.Presl and sect. Cinnamomum is sister to the African Kuloa Trofimov & Rohwer. A recent study indicated that characters of leaf micromorphological anatomy can define the two clades: one possessing reticulate periclinal and the other having non-reticulate periclinal walls. As result, we divided the genus Cinnamomum of Lauraceae into two genera, i.e., Cinnamomum and Camphora Fabr. The generic name Cinnamomum is retained for those species mainly having reticulate periclinal epidermal cell walls, inconspicuous non-perulate terminal buds and usually tripliveined leaves; the oldest generic name, Camphora, is applied to the second group which contains those species mainly possessing non-reticulate periclinal epidermal cell walls, prominent perulate terminal buds and pinnately-veined leaves. A census of the species and their type specimens listed under Cinnamomum in Asia resulted in the transfer of 18 species to Camphora, including 15 new combinations.