Tetraplasandra is a no longer recognised genus of plants in the ivy family, Araliaceae. They are small to medium trees, (rarely shrubs or large trees) of mesic to wet forests.
Some authors have recognized as many as 19 species in Tetraplasandra, while others have recognized as few as six. In 2007, the authors of a scientific paper recommended that the genus be divided into nine species. In 2010, all of these nine species were included in Polyscias subgenus Tetraplasandra, a subgenus of 21 species in the large genus Polyscias, which will comprise about 250 species, when about 90 undescribed species are published.
The range of variation in Tetraplasandra is unusually large for a genus in Araliaceae Most of the species were originally described in other genera which were later merged with Tetraplasandra.
The type species for the genus is T. hawaiensis.
As defined by in 1970, Tetraplasandra is endemic to Hawaii and occurs on six of the eight main islands. Niihau and Kahoolawe are low-lying and dry; consequently, they do not support Tetraplasandra. T. oahuensis, T. kavaiensis, and T. hawaiensis are found on six, five, and four of the islands, respectively. The other species are single-island endemics.
T. oahuensis and T.kavaiensis have done well in cultivation in Southern California. They are sensitive to heat, but very tolerant of shade, and they need some wind protection. In horticulture, T. kavaiensis has often been misidentified as T. meiandra. True T. meiandra is now treated as a synonym of T. oahuensis.
T. gymnocarpa, a rare tree of Oahu, is considered an oddity, since it is the only species in Araliaceae whose flowers have a completely superior ovary.
The genus Tetraplasandra has long been known as a close relative of the obsolete genera Gastonia, Reynoldsia, and Munroidendron. This was confirmed by a pollen study in 1971. 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.
Four Hawaiian names are applied to groups of Tetraplasandra species. T. hawaiensis is known as ohe. T. kavaiensis and T. gymnocarpa are called oheohe. T. waimeae is called ohe kikoola. T. oahuensis and T. lydgatei are called ohe mauka. The related name, ohe makai, is applied to Polyscias sandwicensis, formerly known as Reynoldsia sandwicensis. These names closely correspond to clades currently recognized within Tetraplasandra.
Species in Polyscias subgenus Tetraplasandra
Most of the information in the species list is from Lowry and Plunkett (2010). Synonyms are names of species accepted by Sherff (1955) or by Frodin and Govaerts (2003), except for Tetraplasandra lydgatei and Tetraplasandra bisattenuata, which were resurrected after 2003. For complete synonymy and distribution within the Hawaiian Islands, see Lowry (1990).
Polyscias belensis – New Guinea
Polyscias bisattenuata (= Tetraplasandra bisattenuata) – Kauai
Polyscias borneensis – Borneo, Philippines
Polyscias florosa – Philippines
Polyscias flynnii (Lowry & K.R.Wood) Lowry & G. M. Plunkett (= Tetraplasandra flynnii) – Kauai Polyscias gymnocarpa (Hillebrand) Lowry & G. M. Plunkett (= Tetraplasandra gymnocarpa) – (Oahu) Polyscias hawaiensis (Asa Gray) Lowry & G. M. Plunkett (= Tetraplasandra hawaiensis) – Molokai, Lānai, Maui, island of Hawaii Polyscias kavaiensis (H.Mann) Lowry & G. M. Plunkett (= T. micrantha, T. turbans) – Kauai, Oahu, Lānai, Maui, island of Hawaii Polyscias lanutoensis (= Reynoldsia lanutoensis, Reynoldsia grayana, Reynoldsia tauensis) – Samoa Polyscias lydgatei (= Tetraplasandra lydgatei) – Oahu Polyscias marchionensis (= Reynoldsia marchionensis) – Marquesas Polyscias oahuensis (A.Gray) Lowry & G. M. Plunkett (= T. kaalae, T. kahanana, T. kohalae, T. lanaiensis, T. meiandra, T. munroi, T. oahuensis, T. pupukeensis, T. waianensis) – Kauai, Oahu, Molokai, Lānai, Maui, island of Hawaii Polyscias philipsonii – New Guinea Polyscias pleiosperma (= Reynoldsia pleiosperma) – Samoa Polyscias racemosa (= Munroidendron racemosum) – Kauai Polyscias sandwicensis (= Reynoldsia sandwicensis) – Oahu, Molokai, Lānai, Maui, island of Hawaii Polyscias serratifolia (= Gastonia serratifolia) – Malesia to Solomon Islands Polyscias spectabilis (= Gastonia spectabilis) – New Guinea to Solomon Islands Polyscias verrucosa (= Reynoldsia verrucosa, Reynoldsia tahitiensis) – Tahiti Polyscias waialealae (Rock) Lowry & G. M. Plunkett (= Tetraplasandra waialealae, T. lihuensis) – Kauai Polyscias waimeae (Wawra) Lowry & G. M. Plunkett (= Tetraplasandra waimeae) – Kauai