In 2003, Kew Gardens published a checklist for Araliaceae, in which eight species were recognized for Reynoldsia: four from Samoa, two from Tahiti, one from the Marquesas, and one from Hawaii.
[1] In 2010, a phylogenetic comparison of DNA data showed that Reynoldsia was polyphyletic, consisting of two groups that are not each other's closest relatives.
[3] Reynoldsia was a genus of shrubs to medium-sized trees, mostly of dry habitats, especially the leeward sides of tropical Pacific islands.
William R. Philipson [es] considered Reynoldsia to be hard to distinguish from Tetraplasandra, another defunct genus to which it was closely related.
The genus Reynoldsia was erected in 1854 by Asa Gray[8] in his account of the botany of the United States Exploring Expedition (1838-1842).
[9] The genus was named for Jeremiah N. Reynolds, a plant collector in Chile in the early 19th century.
[16] Christophersen suggested that some plants from a place called Tau might be a fourth species of Reynoldsia in Samoa.
[17] The rare Samoan endemic, Reynoldsia tauensis, was finally published as a separate species in 1968 by Albert C. Smith and Benjamin Clemens Stone.
[19] An examination of the references cited here shows that R. marchionensis is the only species name in Reynoldsia that was ever published for a plant from the Society Islands.
The biphyly of Reynoldsia was confirmed in 2007, in a molecular phylogenetic study of what is now called ''Polyscias'' subgenus Tetraplasandra.
[3] Six of the genera that were recognized in the 2003 checklist (Arthrophyllum, Cuphocarpus, Gastonia, Reynoldsia, Munroidendron, and Tetraplasandra) were subsumed into Polyscias.
[3] Gregory M. Plunkett, Jun Wen, Porter P. Lowry II, Murray J. Henwood, Pedro Fiaschi, and Anthony D. Mitchell.