Chusan Palm
| Trachycarpus fortunei | ||||||||||||||
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 Chusan Palm, semi-cultivated | ||||||||||||||
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| Binomial name | ||||||||||||||
| Trachycarpus fortunei (Hook.) H.Wendl. | ||||||||||||||
Trachycarpus fortunei, commonly known as Chusan Palm, Windmill Palm or Chinese Windmill Palm is a palm native to central and eastern China, where it is one of the hardiest palm species in the world. It grows to 15 m tall on a single stem up to 20-35 cm diameter. The trunk is very rough with the persistent leaf bases clasping the stem as layers of coarse fibrous material. It is a fan palm (Arecaceae under family Corypheae, tribe Livistoneae, subtribe Rhapidinae), with the leaves with the long petiole bare except for two rows of small spines, terminating in a rounded fan of numerous leaflets; each leaf is 140-190 cm long, with the petiole 60-100 cm long, and the leaflets up to 90 cm long with ragged drooping tips. Some specimens are seen with leaf segments having drooping and others straight tips. Both variations were formerly considered to be distinct species and received the names of Trachycarpus excelsa (stiff tips) and Trachycarpus fortunei (drooping tips). The latter species was described by William Jackson Hooker in 1860. Later both species were subsumed under the common name of Trachycarpus excelsa. As this name became invalid in 1931 the species adopted the current valid name of Trachycarpus fortunei (Hook.) H. Wendl. This palm was brought from Japan (Dejima) to Europe by the German physician Philipp Franz von Siebold in 1830 some 15 years before it became more commonly known as the Chusan Palm after Robert Fortune had brought some plants and seeds from China to England.
The flowers are yellow (male) and greenish (female), about 2-4 mm across, borne in large branched panicles up to 1 m long; the fruit is a blue-black, reniform (kidney-shaped) drupe about 1 cm long.
Although not the northernmost naturally occurring palm in the world (Chamaerops humilis grows further north in the Mediterranean region, and Rhapidophyllum and some Sabal species further north on the Atlantic coast of North America), it is one of the hardiest, as it grows at much higher altitudes, up to 2,400 m in the mountains of southern China. This brings it into a climate not only with cold winters, but also cool, moist summers; while Rhapidophyllum may possibly tolerate slightly lower temperatures in winter, it needs much greater summer heat to grow successfully.
Trachycarpus wagnerianus, Dwarf Windmill Palm or Miniature Chusan Palm, formerly sometimes treated as a separate species, is a small-leafed variant of this species.
The common name refers to Chusan Island (now Zhoushan Island), where Robert Fortune first saw cultivated specimens of the species that was later named for him.
Cultivation and uses
Trachycarpus fortunei has been cultivated in China and Japan for thousands of years, grown for its coarse but very strong leaf sheath fibre, used for making ropes, sacks, and other coarse cloth where great strength is important. The extent of this cultivation means that the exact natural range of the species is unknown.
Its tolerance of cool summers makes it highly valued by palm enthusiasts as the palm that can be cultivated the furthest north in the world, being grown successfully in such cool and damp but relatively winter-mild locales as Scotland and the panhandle of Alaska. It is commonly grown in gardens in the British Isles, in Continental Europe (Germany, Netherlands, Belgium, Denmark) the Pacific Northwestern United States, and coastal regions of the Canadian province of British Columbia, as well as extreme south locations, such as Tasmania. The Chusan palm, however, does not grow well in hot climates. The greatest reported cold tolerance is −27.5 °C, survived by four specimens planted in Plovdiv, Bulgaria during a severe cold spell on 6 January 1993 [1].The palm is usually rated for -15 C, or a USDA Zone 7a.
Research on growing this and other palm species in cold climates, usually with varying degrees of protection, has been carried out by Dr. David Francko of the Miami University in Oxford, Ohio.