If 4, they are opposite (along the same radii as) the sepals. The anthers are basifixed. The ovary is superior and consists of 4 carpels that are large compared to the rest of the flower. The carpels are usually separate, but occasionally 2 or 3 of them are fused at the base, or rarely, as far as halfway up. They are erect and stipitate with a suture along the ventral side. A placenta runs along each side of the suture and bears 1 to 3 rows of numerous, tiny ovules. The ovules have been described as having one integument or two. The ovary hardly enlarges after anthesis. The fruit consists of 4 follicles joined at the base. The seeds are numerous and about ½ mm long. Named by William Jackson Hooker in 1840, the name "Tetracarpaea" refers to the four conspicuous and separate carpels. At that time, he wrote:  Hooker did not use the modern system of suffixes for taxonomic ranks. He placed "Tetracarpaea" in what would later be known as the family Cunoniaceae. From that time, until the end of the twentieth century, most authors put it in either Cunoniaceae, Escalloniaceae, or Saxifragaceae. It was believed that these three families were related, but today, they are placed in separate orders. It is now known that Cunoniaceae belongs in Oxalidales. Escalloniaceae is even more distant from "Tetracarpaea", being a member of an asterid group called the campanulids. In the APG III system, it is assigned to the monofamilial order Escalloniales. Phylogenetic analysis of DNA has placed "Tetracarpaea" in the order Saxifragales, and in the "core Saxifragales", but no closer to Saxifragaceae. The family Saxifragaceae is now defined much more narrowly than it had been until 2001. After William Jackson Hooker named "Tetracarpaea" and placed it in Cunoniaceae, he was followed by George Bentham, who placed it in the same family. Bentham mistakenly attributed the name to "Hook.f." (Joseph Dalton Hooker), an error that is still repeated today. In 1865, George Bentham and Joseph Hooker moved "Tetracarpaea" from Cunoniaceae to Escalloniaceae.