Polyscias racemosa

{{Short description|Species of tree}}

{{Speciesbox

|image = Munroidendron racemosum.jpg

|image_caption = Polyscias racemosa growing in Maui Nui Botanical Gardens, Maui, Hawaii.

|status = CR

|status_system = IUCN3.1

|status_ref = {{cite iucn |author=Adams, J.W.A. |date=2016 |title=Polyscias racemosa |volume=2016 |page=e.T34055A83787166 |doi=10.2305/IUCN.UK.2016-2.RLTS.T34055A83787166.en |access-date=20 November 2021}}

|genus = Polyscias

|species = racemosa

|authority = (C.N.Forbes) Lowry & G.M.Plunkett

|synonyms = *Munroidendron racemosum {{au|(C.N.Forbes) Sherff}}

  • Tetraplasandra racemosa {{au|C.N.Forbes}}

|synonyms_ref = {{ThePlantList|id=kew-463847|taxon=Polyscias racemosa|authority=(C.N.Forbes) Lowry & G.M.Plunkett|access-date=3 April 2014}}

}}

Polyscias racemosa, or false 'ohe,{{PLANTS|id=MURA3|taxon=Munroidendron racemosum|accessdate=14 July 2015}} 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. {{ISBN|978-1-84246-048-1}}. (See External links below). It is very rare in the wild and some of its original habitat has been replaced by sugar cane plantations.Earl Edward Sherff. 1956. "Some Recently Collected Dicotyledonous Hawaiian Island and Peruvian Plants". American Journal of Botany 43(7):475-478. It was thought for some time to be probably extinct, but was rediscovered a few years prior to 1967.Benjamin C. Stone. 1967. "A review of the endemic genera of Hawaiian plants" Botanical Review (Lancaster) 33(3):216-259.

Using cladistic methods, phylogenetic studies of DNA have shown that the closest relative of Munroidendron racemosum is Reynoldsia sandwicensis.Gregory M. Plunkett and Porter P. Lowry II. 2010. "Paraphyly and polyphyly in Polyscias sensu lato: molecular evidence and the case for recircumscribing the "pinnate genera" of Araliaceae". Plant Diversity and Evolution (formerly Botanische Jahrbucher) 128(1-2):23-54. {{doi|10.1127/1869-6155/2010/0128-0002}}. 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.Porter P. Lowry II and Gregory M. Plunkett. 2010. "Recircumscription of Polyscias (Araliaceae) to include six related genera, with a new infrageneric classification and a synopsis of species". Plant Diversity and Evolution (formerly Botanische Jahrbucher) 128(1-2):55-84. {{doi|10.1127/1869-6155/2010/0128-0003}}. (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 Hawai‘i. (See External links below). Cultivation procedures for Polyscias racemosa have been studied.Kerin E. Lilleeng-Rosenberger. 2005. Growing Hawai{{okina}}i's Native Plants. Mutual Publishing. {{ISBN|978-1-56647-716-1}}

Description

Polyscias racemosa is a small tree growing to {{convert|25|ft|m|abbr=on}} 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, {{convert|12|in|cm|abbr=on}} long, with oval leaflets, each of which is over {{convert|3|in|cm}} 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.{{cite web |url=http://www2.hawaii.edu/~eherring/hawnprop/mun-race.htm |title=Munroidendron racemosum |work=Hawaiian Native Plant Propagation Database |publisher=University of Hawaiʻi at Mānoa |accessdate=2009-03-03}} 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. {{ISBN|978-0-915809-20-2}}.

File:Polyscias racemosa (5454956091).jpg|Flowers

File:Polyscias racemosa (5455568842).jpg|Inflorescence

File:Starr-090421-6250-Polyscias racemosa-leaves-Keikilani Rd Pukalani-Maui (24952473915).jpg|Leaves

File:Starr 061108-9821 Munroidendron racemosum.jpg|New Leaves

Habitat and range

Polyscias racemosa occurs in coastal mesic and mixed mesic forests at elevations of {{convert|120|-|400|m|ft|abbr=on}}, where it grows on exposed cliffs and ridges. Associated plant species include papala kepau (Pisonia umbellifera), {{okina}}āwikiwiki (Canavalia galeata), {{okina}}ilima (Sida fallax), {{okina}}ōlulu (Brighamia insignis), alahe{{okina}}e (Psydrax odorata), kōpiko (Psychotria spp.), olopua (Nestegis sandwicensis), {{okina}}ahakea (Bobea timonioides), hala pepe (Pleomele aurea), and {{okina}}āla{{okina}}a (Planchonella sandwicensis).{{cite web |url=http://www.centerforplantconservation.org/collection/CPC_ViewProfile.asp?CPCNum=29063 |title=Munroidendron racemosum |work=CPC National Collection Plant Profiles |publisher=Center for Plant Conservation |date=2008-07-22 |accessdate=2009-11-14 |url-status=dead |archiveurl=https://web.archive.org/web/20120223190857/http://www.centerforplantconservation.org/collection/CPC_ViewProfile.asp?CPCNum=29063 |archivedate=2012-02-23 }} It occurs naturally in only three locations on Kaua{{okina}}i: Nounou Mountain, the cliffs of the Nā Pali Coast, and Ha{{okina}}upu 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. {{ISBN|978-0-8493-2673-8}} (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.William R. Philipson. 1970. "A redefinition of Gastonia and related genera (Araliaceae)". Blumea 18(2):497-505. In 1971, a pollen study indicated that Munroidendron might be embedded in Tetraplasandra.Charles C. Tseng. 1971. "Light and Scanning Electron Microscopic Studies on Pollen of Tetraplasandra (Araliaceae) and Relatives". American Journal of Botany 58(6):505-516. 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).Annemarie Costello and Timothy J. Motley. 2007. "Phylogenetics of the Tetraplasandra Group (Araliaceae) Inferred from ITS, 5S-NTS, and Morphology". Systematic Botany 32(2):464-477. This pair is then sister to a monophyletic Tetraplasandra in the sense of 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

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