Phylogeny of Polygoneae (Polygonaceae: Polygonoideae)

Genera included in Polygoneae such as Atraphaxis, Duma, Fallopia, Muehlenbeckia, Polygonella, Polygonum, Oxygonum, and Reynoutria are investigated using a molecular framework. Previous morphological studies had indicated that Polygonum is composed of sections Duravia, Polygonum, and Pseudomollia with the genus Polygonella included as a subsection of Polygonum sect. Duravia. One nuclear (nrITS) and three chloroplast (matK, ndhF, trnL-trnF) regions were analyzed with Maximum Parsimony and Maximum Likelihood methods to address evolutionary relationships within the tribe. The results show that Polygoneae is composed of three main clades: Knorringia as sister to all other taxa within Polygoneae, a clade of Reynoutria and Fallopia(+) Muehlenbeckia, and their sister clade of Atraphaxis, Duma, and Polygonum. The currently accepted sections within Polygonum are recovered and Polygonum sect. Duravia is sister to sections Polygonum and Pseudomollia. With Polygonella included in Polygonum, the appropriate new combinations and names are proposed. In addition, a few species of Polygonum are transferred to Atraphaxis. Oxygonum is not supported as a member of Polygoneae and its exact position awaits additional data.