[2] DNA analysis proved definitive, but the grouping of the two families was a surprise, given their very dissimilar morphologies.

In the older systems of Cronquist (1981, 1988) and Takhtajan (1997), the Gunneraceae were in the Rosidae, and the Myrothamnaceae were in the Hamamelids.

Phloem cells contain a large number of plastids and the leaves have dented borders.

The plants are dioecious and possess small flowers without perianth, and the stigma is, at least weakly, secretory.

Gunnerales characters shared with the core eudicots are cyanogenesis via phenylalanine, metabolic pathways of isoleucine or valine, presence of the DNA sequence of PI-dB motif, and is common to have a small deletion in the sequence of 18S ribosomal DNA.