Tetraplasandra is a no longer recognised genus of plants in the ivy family, Araliaceae.
[6] As defined by William R. Philipson [es] in 1970, Tetraplasandra is endemic to Hawaii[7] and occurs on six of the eight main islands.
[9] T. gymnocarpa, a rare tree of Oʻahu, is considered an oddity, since it is the only species in Araliaceae whose flowers have a completely superior ovary.
[10] The genus Tetraplasandra has long been known as a close relative of the obsolete genera Gastonia, Reynoldsia, and Munroidendron.
[11] In 2010, those four genera, along with Arthrophyllum and Cuphocarpus, were all sunk into Polyscias, raising the number of species in that genus from about 100 to 159.
[13] The name is derived from Greek, tetraplasios, "fourfold", and andros, "male, stamen".
[19] Earl Edward Sherff did not consider the two species named by Mann to be truly distinct.
[2] From 1864 to 1868, Berthold Carl Seemann published a series of articles in the Journal of Botany, British and Foreign, all of which were entitled "Revision of the natural order Hederaceae".
[23][24] In 1873, Heinrich Wawra von Fernsee named a new species from Kauaʻi as Tetraplasandra waimeae.
[26] This work was published posthumously by his son, William Francis Hillebrand to whom the name Pterotropia is often incorrectly attributed.
[2][5] Wilhelm B. Hillebrand put two species in Tetraplasandra: T. hawaiensis and T. waimeae.
[3] In 1898, in a monograph on Araliaceae for Die Natürlichen Pflanzenfamilien, Hermann Harms adopted Hillebrand's Pterotropia, but sank Triplasandra back into Tetraplasandra.
[28] In 1917, Charles Noyes Forbes named another species from Kauaʻi as Tetraplasandra racemosa.
[29] Both of these are still recognized as distinct species, but in 1952, Earl Edward Sherff erected the new genus Munroidendron for T.
Sherff considered Tetraplasandra to consist of three species from Malesia and 19 from Hawaii.
Sherff recognized the uniqueness of T. hawaiensis, a judgement that was corroborated by subsequent evidence.
He understood that T. waimeae and T. waialealae are closely related and that these two belong in a group with T. oahuensis, T. lydgatei, and T. bisattenuata.
In this study, the former genus Tetraplasandra was resolved as monophyletic and consisting of three clades.
[3] Tetraplasandra oahuensis is heterogeneous and probably polyspecific, but the authors recommended that further studies be conducted before any attempt to divide it.
[3] In 2010, a molecular phylogenetic study was published for the seven genera which at that time constituted the pinnate Araliaceae.
[34] It was found that the six smaller genera are all embedded in the large genus Polyscias.
In a companion paper, published simultaneously, the six smaller genera (Arthrophyllum, Cuphocarpus, Gastonia, Reynoldsia, Munroidendron, and Tetraplasandra) were placed in synonymy under Polyscias, thereby raising the number of species in that genus from about 100 to 159.
Basal relationships in Polyscias subgenus Tetraplasandra remain obscure because of insufficient taxon sampling in phylogenetic studies.
Gregory M. Plunkett, Jun Wen, Porter P. Lowry II, Murray J. Henwood, Pedro Fiaschi, and Anthony D. Mitchell.