Polyscias racemosa, or false 'ohe, is a species of flowering plant in the family Araliaceae. As Munroidendron racemosum, the species was until recently considered to be the only species in the monotypic genus Munroidendron. With the change in classification, Munroidendron is now obsolete. Polyscias racemosa is endemic to the Hawaiian island of Kauai.David G. Frodin and Rafaël Govaerts. 2003. World Checklist and Bibliography of Araliaceae. Royal Botanic Gardens, Kew. . (See External links below). It is very rare in the wild and some of its original habitat has been replaced by sugar cane plantations. It was thought for some time to be probably extinct, but was rediscovered a few years prior to 1967.
Using cladistic methods, phylogenetic studies of DNA have shown that the closest relative of Munroidendron racemosum is Reynoldsia sandwicensis. These two species are now known as Polyscias racemosa and Polyscias sandwicensis, respectively. They are two of the 21 species now placed in Polyscias subgenus Tetraplasandra. (See External links below).
Polyscias racemosa is known in cultivation in Hawaii.Clyde T. Imada, George W. Staples, and Derral R. Herbst. undated. Annotated Checklist of Cultivated Plants of Hawaiʻi. (See External links below). Cultivation procedures for Polyscias racemosa have been studied.Kerin E. Lilleeng-Rosenberger. 2005. Growing Hawaii's Native Plants. Mutual Publishing.
Description Polyscias racemosa is a small tree growing to tall, with a straight trunk, spreading branches, and smooth, grey bark.Warren L. Wagner, Derral R. Herbst, and Sy H. Sohmer. Manual of the Flowering Plants of Hawaii, Revised Edition, 1999. Bishop Museum Press: Hololulu Like many members of Polyscias, it is sparingly branched and thick-stemmed, with large imparipinnate leaves, but not as extreme in these characteristics as is Polyscias nodosa.
Its leaves are pinnate, long, with oval leaflets, each of which is over long. These trees are dry season deciduous, dropping most of their leaves during their summer blooming season. Its small, pale yellow flowers hang in long, rope-like strands. The inflorescence is racemose in form, with up to 250 flowers.Peter S. Green (author) and Mary Grierson (illustrator). 1996. A Hawaiian Florilegium: Botanical Portraits from Paradise. University of Hawaii Press: Honolulu, Hawaii. .
Habitat and range Polyscias racemosa occurs in coastal mesic and mixed mesic forests at elevations of , where it grows on exposed cliffs and ridges. Associated plant species include papala kepau (Pisonia umbellifera), āwikiwiki (Canavalia galeata), ilima (Sida fallax), ōlulu (Brighamia insignis), alahee (Psydrax odorata), kōpiko (Psychotria spp.), olopua (Nestegis sandwicensis), ahakea (Bobea timonioides), hala pepe (Pleomele aurea), and ālaa (Planchonella sandwicensis). It occurs naturally in only three locations on Kauai: Nounou Mountain, the cliffs of the Nā Pali Coast, and Haupu Ridge near Nāwiliwili Bay.
History Polyscias racemosa first entered the botanical literature in 1917, when it was described and named as Tetraplasandra racemosa by Charles Noyes Forbes.Charles Noyes Forbes. 1917. "New Hawaiian Plants.-VI." Occasional Papers of the Bernice Pauahi Bishop Museum 6(4):51. (See External links below).
Earl Edward Sherff felt that this species was uniquely distinct from the rest of Tetraplasandra, so he erected a new genus for it, Munroidendron, in 1952.Munroidendron in International Plant Names Index. (see External links below). The genus was named for George Campbell Munro (1866-1963), described by Umberto Quattrocchi as "a pioneer in Hawaiian ornithology, botany, and horticulture; plant collector in the Hawaiian Islands".Umberto Quattrocchi. 2000. CRC World Dictionary of Plant Names, volume III. CRC Press: Baton Rouge, New York, London, Washington DC. (vol. III). (see External links below). Dendron is a Greek word for "tree". Munro was apparently the first collector to see his eponymous genus, Munroidendron.Earl Edward Sherff. 1952. "Munroidendron, a new genus of Araliaceous trees from the island of Kauai". Botanical Leaflets 7(section V):21-24. published by the author.
Sherff separated Munroidendron from Tetraplasandra on the basis of five characters: the absence of umbellules, the arrangement of the flowers in a raceme, the sunken, diamond-shaped pedicel scars, the long persistence of the subtending floral bracts, and the insertion of the stamens in only one whorl, even when numerous. It has been shown that, in spite of its appearance, the inflorescence is not truly a raceme because it is determinate.
Sherff divided the species now known as Polyscias racemosa into three varieties: var. racemosa, var. forbesii, and var. macdanielsii. These have been described as "not sufficiently distinct to be retained".
The establishment of Munroidendron was contentious from the beginning. William R. Philipson said that Munroidendron "comprises a single species with such a distinct inflorescence and corolla that it can well claim generic status. In 1971, a pollen study indicated that Munroidendron might be embedded in Tetraplasandra. This result was not supported by molecular phylogenetic studies based on DNA sequences of nuclear and chloroplast DNA regions. These studies show that Polyscias sandwicensis (formerly Reynoldsia sandwicensis is not most closely related to other species of Reynoldsia, but is sister to Polyscias racemosa, (formerly Munroidendron). This pair is then sister to a monophyletic Tetraplasandra as described by Philipson (1970). This pair of species and the nine species formerly in Tetraplasandra form a clade and comprise all of the Hawaiian species of Polyscias. The 11 species of this "Hawaiian clade" and 10 species from Malesia, Melanesia, and southern Polynesia constitute Polyscias subgenus Tetraplasandra.
References
External links
World Checklist and Bibliography of Araliaceae World Checklists kewbooks Scientific Publications Kew Gardens Lowry & Plunkett.2010 Hawaii Barcoding University of Hawaii at Hilo Munroidendron Annotated Checklist of Cultivated Plants of Hawaiʻi Botany Databases HBS Databases Hawaii Biological Survey Research Bishop Museum New Hawaiian Plants - VI, page 51 View Book Occasional papers of Bernice P. Bishop Museum, vol. 6, part 4 (1917) O Titles BHL Munroidendron Plant Names IPNI Munroidendron (Search Exact) At: Names At: Tropicos At: Science and Conservation At: Missouri Botanical Garden CRC World Dictionary of Plant Names: M-Q At: Botany & Plant Science At: Life Science At: CRC Press Munroidendron At: List of Genera At: Araliaceae At: List of families At: Families and Genera in GRIN At: Queries At: GRIN taxonomy for plants subgenus Tetraplasandra Polyscias Araliaceae Apiineae Apiales In: ··· Embryophyta At: Streptophytina At: Streptophyta At: Viridiplantae At: Eukaryota At: Taxonomy At: UniProt Polyscias racemosa Araliacee Family Index Plants of Hawaii Starr Environmental Hawaiian Ecosystems at Risk Polyscias racemosa At: Choose a Plant At: Meet the Plants At: National Tropical Botanical Garden