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''Gnetum'' is a genus of gymnosperms, the sole genus in the family Gnetaceae and order Gnetales. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect pollinated as their fossils occur in association with the extinct pollinating scorpionflies.〔Ren D, Labandeira CC, Santiago-Blay JA, Rasnitsyn A, Shih CK, Bashkuev A, Logan MA, Hotton CL, Dilcher D. (2009). Probable Pollination Mode Before Angiosperms: Eurasian, Long-Proboscid Scorpionflies. Science, 326 (5954), 840-847. 〕 Molecular phylogenies based on nuclear and plastid sequences from most of the species indicate hybridization among some of the Southeast Asian species. Fossil-calibrated molecular-clocks suggest that the ''Gnetum'' lineages now found in Africa, South America, and Southeast Asia are the result of ancient long-distance dispersal across seawater.〔Won H, Renner SS: The internal transcribed spacer of nuclear ribosomal DNA in the gymnosperm ''Gnetum''. Molecular Phylogenetics and Evolution 2005, 36:581-597. 〕 〔Won, H., and S. S. Renner. 2006. Dating dispersal and radiation in the gymnosperm ''Gnetum'' (Gnetales) – clock calibration when outgroup relationships are uncertain. Systematic Biology 55(4): 610-622. 〕 ==Species== *''Gnetum'' sect. ''Gnetum'' * *''Gnetum'' subsect. ''Gnetum'' - 2 species of trees; southeast Asia, Pacific Islands * * *''Gnetum gnemon'' - Tibet, Yunnan, Assam, Indochina, Nicobar Islands, Malaysia, Indonesia, Philippines, New Guinea, Melanesia, Micronesia * * *''Gnetum costatum'' - New Guinea, Solomon Islands * *''Gnetum'' subsect. ''Micrognemones'' - 2 species of lianas; tropical west Africa * * *''Gnetum africanum'' - central Africa from Cameroon to Angola * * *''Gnetum buchholzianum'' - central Africa from Nigeria to Zaire * *''Gnetum'' subsect. ''Araeognemones'' - 9 species of lianas; tropical South America and Central America - Ituá * * *''Gnetum camporum'' - Venezuela * * *''Gnetum leyboldii'' - Costa Rica, Panama, Venezuela, Colombia, Ecuador, Peru, northwestern Brazil * * *''Gnetum nodiflorum'' - Guianas, Venezuela, Colombia, Ecuador, Peru, northwestern Brazil * * *''Gnetum paniculatum'' - Guianas, Venezuela, northwestern Brazil * * *''Gnetum schwackeanum'' - Amazonas State of southern Venezuela, northwestern Brazil * * *''Gnetum urens'' - Guianas, Venezuela, Peru, northwestern Brazil * * *''Gnetum venosum'' - Bolívar State of southern Venezuela, northwestern Brazil *''Gnetum'' sect. ''Scandentia'' - about 20 species of lianas; southern Asia * *''Gnetum'' subsect. ''Stipitati'' * * *''Gnetum arboreum'' - Luzon in Philippines * * *''Gnetum contractum'' - southern India * * *''Gnetum edule'' - southern India * * *''Gnetum gracilipes'' - Yunnan + Guangxi in China * * *''Gnetum latifolium'' - Assam, much of Southeast Asia, New Guinea, Bismarck Archipelago * * *''Gnetum montanum'' - Himalayas, southern China, northern Indochina * * *''Gnetum oblongum'' - Bangladesh, Myanmar * * *''Gnetum pendulum'' - Tibet, southern China * * *''Gnetum tenuifolium'' - Peninsular Malaysia, Thailand, Sumatra * *''Gnetum'' subsect. ''Sessiles'' * * *''Gnetum acutum'' - Sarawak * * *''Gnetum bosavicum'' - Papua New Guinea * * *''Gnetum catasphaericum'' - southern China * * *''Gnetum cuspidatum'' - Indochina, Indonesia, Malaysia, Philippines * * *''Gnetum diminutum'' - Borneo * * *''Gnetum formosum'' - Vietnam * * *''Gnetum giganteum'' - Guangxi in China * * *''Gnetum globosum'' - Pahang in Malaysia * * *''Gnetum gnemonoides'' - New Guinea, Bismarck Archipelago, Indonesia, Philippines * * *''Gnetum hainanense'' - southern China * * *''Gnetum klossii'' - Sabah * * *''Gnetum leptostachyum'' - Laos, Thailand, Vietnam, Borneo * * *''Gnetum loerzingii'' - Sumatra * * *''Gnetum luofuense'' - Fujian, Guangdong, Jiangxi * * *''Gnetum macrostachyum'' - Indochina, Indonesia, Malaysia, New Guinea * * *''Gnetum microcarpum'' - Myanmar, Thailand, Malaysia, Borneo, Sumatra * * *''Gnetum neglectum'' - Borneo * * *''Gnetum oxycarpum'' - Sumatra * * *''Gnetum parvifolium'' - Laos, Vietnam, southern China * * *''Gnetum raya'' - Borneo * * *''Gnetum ridleyi'' - Peninsular Malaysia 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gnetum」の詳細全文を読む スポンサード リンク
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