Argyroxiphium grayanum, commonly known as the greensword, is a species of flowering plant in the family Asteraceae, and a member of the silversword alliance, a group of over 50 species which are diverse in morphology and habitat but are genetically closely related.[3]
The silversword alliance provides a convincing natural case study in evolution by adaptive radiation, with the greensword representing one extreme of the genus' plasticity.[4] Some Argyroxiphium, including the well-known Haleakala and Mauna Kea silverswords, live in harsh alpine desert-like conditions of heat, sun, wind, and aridity, and are drought-adapted plants capable of storing water as a gel in leaf structures which are normally air pockets in other plants.[5] However, A. grayanum is a bog plant adapted to very different conditions – excessive moisture, lack of regular sunlight, and cool temperatures, and its leaves are non-succulent like those of the related genus Dubautia.[6]
Argyroxiphium grayanum is a perennial plant endemic to the island of Maui in Hawaii. Its growth form is typically a low shrub up to 2 m high, erect, with an erect single-stemmed monocarpic rosette shape, though in the interior of bogs it typically grows as a dwarf shrub under 30 cm high. It has green, 5–11-nerved, narrowly elliptic-ligulate leaves which are broadest above the middle.[7] It occurs only in and around montane cloud forest bogs at elevations ranging from about 1,200 to 2,050 m. The sites receive from about 300 to over 1,000 cm precipitation per year.[8][9] It is most abundant along the upper rim of Kīpahulu Valley on East Maui and near the summit of Puʻu Kukui on West Maui.[10] The latter region is also home to a related species, the ʻEke silversword (A. caliginis).[5] Despite their close relationship and shared habitat, the two species differ in several ways beyond the coloring of their lance-shaped leaves, with silversword possessing a distinctive sheen.
Most Argyroxiphium species generally produce one inflorescence, after which the plant dies. Neither A. grayanum nor the sympatric ʻEke silversword (A. caliginis) follow this pattern in a strict sense. Both species flower infrequently compared to the mass flowerings of the Haleakala silversword, and produce multiple branches such that only some rosettes of a given plant die back in any given year. A. caliginis additionally reproduces by way of runners or prostrate stems which root and spread.[5]
Other greensword speciesedit
Another greensword species A. virescens, was formerly found on East Maui only, but is now apparently extinct.[11]
Adaptive radiation and the silversword allianceedit
Based on biosystematics and molecular studies, all of the silversword alliance species are thought to have evolved from a single ancestor, related to the tarweed (Carlquistia muirii) found in western North America.[12] That several spontaneous hybrids have been observed supports this hypothesis.[13] If true, the adaptive radiation of the tarweed/silversword/greensword into extremely diverse morphologies and habitats is an extraordinary case history of evolution.[14]
Referencesedit
^"NatureServe Explorer Argyroxiphium grayanum". NatureServe Explorer Argyroxiphium grayanum. Arlington Virginia, United States of America: NatureServe. 3 June 2022. NatureServe Element Code:PDAST0P030. Retrieved 23 June 2022.
^Faber-Langendoen, D; Nichols, J; Master, L; Snow, K; Tomaino, A; Bittman, R; Hammerson, G; Heidel, B; Ramsay, L; Teucher, A; Young, B (2012). NatureServe Conservation Status Assessments: Methodology for Assigning Ranks (PDF) (Report). Arlington, Virginia, United States of America: NatureServe.
^"Adaptive Radiation of the Hawaiian Silversword Alliance: Origin and Relationships". 17 April 2000. Retrieved 17 December 2009.
^"Adaptive Radiation of the Hawaiian Silversword Alliance: Ecological and Physiological Adaptations". University of Hawaii Botany Department. 22 March 1997. Retrieved 17 December 2009.
^ abcCarlquist, Sherwin (1980). Hawaii, a natural history: geology, climate, native flora and fauna above the shoreline. Lawai: Pacific Tropical Botanical Garden. pp. 264, 266.
^"Adaptive Radiation of the Hawaiian Silversword Alliance: Leaf Morphology and Anatomy". University of Hawaii Botany Department. 14 February 2004. Retrieved 17 December 2009.
^Wagner, W. L., D. R. Herbst, and S. H. Sohmer (1990). Manual of the Flowering Plants of Hawaii. Honolulu: University of Hawaii Press.
^"Hawaiian Native Plant Genera – Asteraceae". University of Hawaii Botany Department. Retrieved 8 December 2009.
^"Hawaii Statewide GIS Data – Rainfall". Retrieved 23 December 2009.
^Carr, G.D, and Medeiros, A.M. 1998. A remnant greensword population from Puʻu ʻAlaea, Maui, with characteristics of Argyroxiphium virescens (Asteraceae). Pacific Science 52(1):61–68
^Bruegmann, M.M. & Caraway, V. 2003. Argyroxiphium virescens. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Retrieved 8 December 2009.
^"Hawaiian Native Plant Genera – Asteraceae". University of Hawaii Botany Department. Retrieved 8 December 2009.
^"Natural and Artificial Hybrids in the Hawaiian Silversword Alliance". University of Hawaii Botany Department. Retrieved 8 December 2009.
^"Adaptive Radiation and Hybridization in the Hawaiian Silversword Alliance". University of Hawaii Botany Department. Retrieved 8 December 2009.
External linksedit
Media related to Argyroxiphium grayanum at Wikimedia Commons
Data related to Argyroxiphium grayanum at Wikispecies
January 01, 1970
argyroxiphium, grayanum, commonly, known, greensword, species, flowering, plant, family, asteraceae, member, silversword, alliance, group, over, species, which, diverse, morphology, habitat, genetically, closely, related, conservation, status, critically, impe. Argyroxiphium grayanum commonly known as the greensword is a species of flowering plant in the family Asteraceae and a member of the silversword alliance a group of over 50 species which are diverse in morphology and habitat but are genetically closely related 3 Argyroxiphium grayanum Conservation status Critically Imperiled NatureServe 1 2 Scientific classification Kingdom Plantae Clade Tracheophytes Clade Angiosperms Clade Eudicots Clade Asterids Order Asterales Family Asteraceae Genus Argyroxiphium Species A grayanum Binomial name Argyroxiphium grayanum Hillebr O Deg The silversword alliance provides a convincing natural case study in evolution by adaptive radiation with the greensword representing one extreme of the genus plasticity 4 Some Argyroxiphium including the well known Haleakala and Mauna Kea silverswords live in harsh alpine desert like conditions of heat sun wind and aridity and are drought adapted plants capable of storing water as a gel in leaf structures which are normally air pockets in other plants 5 However A grayanum is a bog plant adapted to very different conditions excessive moisture lack of regular sunlight and cool temperatures and its leaves are non succulent like those of the related genus Dubautia 6 Contents 1 Description 2 Other greensword species 3 Adaptive radiation and the silversword alliance 4 References 5 External linksDescription editArgyroxiphium grayanum is a perennial plant endemic to the island of Maui in Hawaii Its growth form is typically a low shrub up to 2 m high erect with an erect single stemmed monocarpic rosette shape though in the interior of bogs it typically grows as a dwarf shrub under 30 cm high It has green 5 11 nerved narrowly elliptic ligulate leaves which are broadest above the middle 7 It occurs only in and around montane cloud forest bogs at elevations ranging from about 1 200 to 2 050 m The sites receive from about 300 to over 1 000 cm precipitation per year 8 9 It is most abundant along the upper rim of Kipahulu Valley on East Maui and near the summit of Puʻu Kukui on West Maui 10 The latter region is also home to a related species the ʻEke silversword A caliginis 5 Despite their close relationship and shared habitat the two species differ in several ways beyond the coloring of their lance shaped leaves with silversword possessing a distinctive sheen Most Argyroxiphium species generally produce one inflorescence after which the plant dies Neither A grayanum nor the sympatric ʻEke silversword A caliginis follow this pattern in a strict sense Both species flower infrequently compared to the mass flowerings of the Haleakala silversword and produce multiple branches such that only some rosettes of a given plant die back in any given year A caliginis additionally reproduces by way of runners or prostrate stems which root and spread 5 Other greensword species editAnother greensword species A virescens was formerly found on East Maui only but is now apparently extinct 11 Adaptive radiation and the silversword alliance edit nbsp Based on biosystematics and molecular studies all of the silversword alliance species are thought to have evolved from a single ancestor related to the tarweed Carlquistia muirii found in western North America 12 That several spontaneous hybrids have been observed supports this hypothesis 13 If true the adaptive radiation of the tarweed silversword greensword into extremely diverse morphologies and habitats is an extraordinary case history of evolution 14 References edit NatureServe Explorer Argyroxiphium grayanum NatureServe Explorer Argyroxiphium grayanum Arlington Virginia United States of America NatureServe 3 June 2022 NatureServe Element Code PDAST0P030 Retrieved 23 June 2022 Faber Langendoen D Nichols J Master L Snow K Tomaino A Bittman R Hammerson G Heidel B Ramsay L Teucher A Young B 2012 NatureServe Conservation Status Assessments Methodology for Assigning Ranks PDF Report Arlington Virginia United States of America NatureServe Adaptive Radiation of the Hawaiian Silversword Alliance Origin and Relationships 17 April 2000 Retrieved 17 December 2009 Adaptive Radiation of the Hawaiian Silversword Alliance Ecological and Physiological Adaptations University of Hawaii Botany Department 22 March 1997 Retrieved 17 December 2009 a b c Carlquist Sherwin 1980 Hawaii a natural history geology climate native flora and fauna above the shoreline Lawai Pacific Tropical Botanical Garden pp 264 266 Adaptive Radiation of the Hawaiian Silversword Alliance Leaf Morphology and Anatomy University of Hawaii Botany Department 14 February 2004 Retrieved 17 December 2009 Wagner W L D R Herbst and S H Sohmer 1990 Manual of the Flowering Plants of Hawaii Honolulu University of Hawaii Press Hawaiian Native Plant Genera Asteraceae University of Hawaii Botany Department Retrieved 8 December 2009 Hawaii Statewide GIS Data Rainfall Retrieved 23 December 2009 Carr G D and Medeiros A M 1998 A remnant greensword population from Puʻu ʻAlaea Maui with characteristics of Argyroxiphium virescens Asteraceae Pacific Science 52 1 61 68 Bruegmann M M amp Caraway V 2003 Argyroxiphium virescens In IUCN 2009 IUCN Red List of Threatened Species Version 2009 2 lt www iucnredlist org gt Retrieved 8 December 2009 Hawaiian Native Plant Genera Asteraceae University of Hawaii Botany Department Retrieved 8 December 2009 Natural and Artificial Hybrids in the Hawaiian Silversword Alliance University of Hawaii Botany Department Retrieved 8 December 2009 Adaptive Radiation and Hybridization in the Hawaiian Silversword Alliance University of Hawaii Botany Department Retrieved 8 December 2009 External links edit nbsp Media related to Argyroxiphium grayanum at Wikimedia Commons nbsp Data related to Argyroxiphium grayanum at Wikispecies Retrieved from https en wikipedia org w index php title Argyroxiphium grayanum amp oldid 1181175369, wikipedia, wiki, book, books, library,
