[4] It has a disjunct distribution, with Peridiscus occurring in Venezuela and northern Brazil, Whittonia in Guyana,[5] Medusandra in Cameroon, and Soyauxia in tropical West Africa.

The Peridiscaceae are small trees or erect shrubs of wet tropical forests.

The leaves are stipulate, alternate, and simple, with margins that are entire or remotely crenulate (Medusandra).

Medusandra lacks a nectary disk and has five stamens, inserted opposite the petals, and alternating with five long, hairy staminodes.

[10] The family Flacourtiaceae was, as Hermann Sleumer said, a fiction,[12][13] and Peridiscus was, from the outset, one of its most doubtful members.

[17] In an accompanying article, Charles Russell Metcalfe discussed its close relationship to Peridiscus.

In the year 2000, a DNA sequence for the rbcL gene of Whittonia was produced and used in a molecular phylogenetic study of the eudicots.

[18] This study placed Peridiscaceae in a clade with Elatinaceae and Malpighiaceae, a very surprising and unexpected result.

[19] It was soon found that the rbcL sequence for Whittonia was a chimera, formed by DNA from unidentified plants that had contaminated the sample.

In 2004, using DNA from Peridiscus, it was shown that Elatinaceae and Malpighiaceae are indeed sister families and that Peridiscaceae belong to Saxifragales.

[20] Medusandra and Soyauxia, meanwhile, were listed in APG II in an appendix entitled "TAXA OF UNCERTAIN POSITION".

[3] When the APG III system was published in October 2009, Peridiscaceae was expanded to include Medusandra and Soyauxia.

Peridiscus and Whittonia are undoubtedly sister taxa due to their many shared morphological characters.