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Hardy palms are any of the species of palm (Arecaceae) that are able to withstand brief periods of colder temperatures and even occasional snowfall. A few palms are native to higher elevations of south Asia, and a few can tolerate hard freezes with little or no damage. Many of these "hardy " species can be cultivated in warm temperate climates. The hardiest species are found in the genera ''Rhapidophyllum'', ''Sabal'', and ''Trachycarpus''. Members of these and other genera are sometimes grown in areas where they are not truly hardy, overwintering with the aid of various kinds of artificial protection. The minimum temperature a palm can sustain depends on a variety of factors, such as humidity, size and age of the palm, daytime high temperatures, or the length of time the temperature is at the minimum. for several days will do far more damage to a palm than an overnight low of for an hour or so. ==Fan palms== The fan palms (Arecaceae tribe Corypheae; palms with fan-shaped leaves) include all of the hardiest palms. *Windmill Palms (''Trachycarpus fortunei'', ''T. takil'') – the best known cold-hardy palms, these tough species are native to eastern China and the Himalaya mountains. Hardy to about 0 F/-18 C. Although not growing so far north (to about 31°N) as the Needle Palm, they do grow at high altitudes where temperatures are cool. It is also tolerant of low summer temperatures. Mature ''Trachycarpus'' trees have been successfully grown as far north as 58°N in northern Scotland. Mature specimens can also be found in most parts of Ireland, England, southwestern Canada (in the city of Vancouver and on Vancouver Island), eastern Asia (Japan, China, South Korea), Southern Switzerland (Ticino) and in parts of Australia and New Zealand. In the United States ''Trachycarpus'' is grown as far north as Seattle on the Pacific coast and Long Island/coastal New Jersey on the Atlantic Coast.〔(【引用サイトリンク】title=Cold Hardy Palms )〕 *Mediterranean Fan Palm (''Chamaerops humilis'') – The only palm native to southern Europe besides the Cretan Date Palm, and very drought-tolerant. Hardy to , but does prefer hot summers. Despite the fact that this palm is less hardy than many palms listed here, it has the northernmost native habitat because of the mild Mediterranean climate. It is found in abundance across most of southwestern Europe and northwestern Africa. It is a very slow-growing plant. The blue form of the species, native to high elevations of the Atlas Mountains, has recently been introduced into the trade and early reports indicate that it may be 5C (9F) or more degrees hardier than the green form. *Needle Palm (''Rhapidophyllum hystrix'') – This clustering and usually trunkless palm is native to the subtropical southeastern United States, from central Florida to Georgia, Mississippi, South Carolina and Alabama in the United States. It is considered hardy to USDA Hardiness Zone 6b and is cultivated along the West Coast of the USA from California to Seattle and along the East Coast from Florida to southern Connecticut. They have proven hardy in the Tennessee valley region and up into the lower Ohio Valley. During the winter, it can tolerate temperatures as low as for short time periods. The needle palm is very slow-growing and rarely reaches heights of over . There are documented specimens that have been growing in White County, Tennessee, since the early part of the 1960s, as well as United States National Arboretum in the Asia Valley section, in Washington D.C., that are at in height. A Needle Palm has been growing since 2003 in the St. Louis suburb of Alton, Illinois. *Mazari Palm (''Nannorrhops richtiana'') – This palm, native to the dry, mountainous terrains of northern Pakistan, Afghanistan, Iran and surrounding regions, is also thought to be extremely cold hardy (perhaps to about ), though also requiring hot summers and dry soils. However, due to its limited availability in cultivation, not much is known about this palm. Mazari Palm is not easy to grow, perfect drainage and full sun are required for this palm to survive. This palm will not tolerate wet freezes. *Saw Palmetto (''Serenoa repens'') - These palms are native to the southeastern United States, most commonly along the Atlantic and Gulf Coastal plains, but also as far inland as southern Arkansas, this bushy palm is hardy to about . This bushy palm grows in abundance within wetlands and subtropical grasslands of central and northern Florida. Extract from Saw Palmetto is often used to treat problems with the prostate. *''Sabal'' palms (palmettos; 13 species) – These palms are native to the southeastern United States, Central America, and the Caribbean. The Cabbage Palmetto (''Sabal palmetto''), the state tree of both Florida and South Carolina, is very common on the southeast coast of the United States. The species is considered hardy to USDA Hardiness Zone 8, and may survive short periods of temperatures as low as . The Dwarf Palmetto (''S. minor'') is the hardiest species in the genus. The cultivar 'McCurtain' is considered the hardiest, to USDA zone 6b, like the needle palm. It can tolerate short periods of temperatures as low as . Sabal minor, a dwarf palmetto that it forms a subterranean trunk, is the most cold hardy, able to take short periods with near temperatures. The Mexican Palmetto (''Sabal mexicana'') is a close relative of the Cabbage Palmetto, native to southern Texas and northern Mexico. *''Washingtonia'' palms (''Washingtonia filifera, W. robusta'') – These palms are native to southern California and northwest Mexico, growing as high as in their native habitat. California Washingtonia (''W. filifera'') is hardy to ; it prefers a dry Mediterranean climate, though it still grows in areas with humid subtropical climates like Brisbane, Sydney, Houston, and New Orleans. It is sometimes grown in containers, or planted as short-term specimens in areas where it is not quite hardy. Mexican Washingtonia (''W. robusta'') is somewhat less hardy, native to northern Mexico (Baja California Peninsula). It has a more robust trunk and stiffer leaves than ''W. filifera'', and is hardy to . *''Livistona australis'' – It is native to southeastern Australia. *''Rhapis excelsa'' – It is native to China and it is hardy to about . 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「List of hardy palms」の詳細全文を読む スポンサード リンク
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