The fruit is in the form of a black or dark brown unwinged achene, three-sided to more or less globe-shaped, at least partly enclosed by the persistent tepals.

Within the tribe, it is most closely related to the genera Reynoutria and Fallopia s.s., forming the so-called "RMF clade".

Fallopia ciliinodis) Duma Atraphaxis Polygonum Reynoutria Muehlenbeckia Fallopia s.s. As of March 2019[update], Plants of the World Online recognized 24 species (see note below):[1] Some sources, including Plants of the World Online, regard M. adpressa as a synonym of M. australis.

[7] Three species have been transferred to the genus Duma:[8] All members of the RMF clade appear to have the potential to become invasive, in some cases via vigorous hybrids.

[6] The related Muehlenbeckia complexa has established populations in southern parts of Britain and in the Channel Islands,[6] and is a problematic invasive species in the San Francisco area.