Chinese hemp palm
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Chinese hemp palm ( Trachycarpus fortunei ), habitat . |
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| Trachycarpus fortunei | ||||||||||||
| ( Hook. ) H. Wendl. |
The Chinese windmill palm ( Trachycarpus fortunei ) in the Alpine countries as Ticino Palm brand and sell, and this affects the local distribution as a neophyte refers, belongs to the subfamily coryphoideae in the family of the palm plants (Arecaceae).
In Switzerland, the hemp palm, which was originally planted there as an ornamental plant, is one of the invasive plants because it is a threat to native trees. It is therefore listed there on the black list of invasive species .
history
The Chinese hemp palm, named after the English explorer Robert Fortune , was first mentioned in 1712 by the German doctor and Japan traveler Engelbert Kämpfer under the Japanese name "Shuro". The Swedish doctor Carl Peter Thunberg described the Chamaerops excelsa in 1784 ; Today's hemp palm was carried under this name until 1861, when Hermann Wendland placed it in the newly established genus Trachycarpus . In 1830 the first hemp palms from Japan ( Dejima ) came to Europe as seeds by the German doctor and naturalist Philipp Franz von Siebold , and in 1850 the palm was described in detail by Carl Friedrich Philipp von Martius under the name Chamaerops excelsa . Until 1931 it was called Trachycarpus excelsa , since then the correct botanical name has been Trachycarpus fortunei , after it had been proven that Thunberg had described two Rhapis species under Chamaerops excelsa .
description
Habitus
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Trachycarpus fortunei is a medium-high fan palm that reaches a maximum height of 12 to 15 m with age. The trunk is completely covered with brown fibers in the youth and only in the upper part later . These fibers are the remains of the leaf sheaths and the upwardly directed leaf rests. The leaf bases and fibers remain attached to the trunk for a very long time, sometimes almost the entire life of the plant, which in adult hemp palms can be 70 to 110 cm in circumference. With older hemp palms, however, it can often be observed that the leaf bases detach from the trunk from the base of the trunk, so that in old age the lower part of the trunk is often bare. There are also hemp palms in which the leaf bases peel off earlier.
The trunk is upright and reaches a height of 10 m or more. From a stem height of about 1 meter, either male or female inflorescences appear in spring. The cylindrical wooden body has a diameter of 15 to 20 cm, but is completely covered from the base to the tip of the trunk with permanently adhering leaf bases, and together with the dense network of frayed fibers, the trunk diameter is 25 to 35 cm.
Trachycarpus fortunei is now cultivated as an ornamental plant in many gardens in Europe, making it the most commonly planted palm in Europe. It probably owes its popularity to the fact that it has proven to be one of the most robust species of all the palm trees tested here. The leaf crown can consist of 50 (and more) green compartments. Gradually, however, the oldest fronds turn yellow from the tips and dry up over time. Most gardeners then remove these oldest fronds. If these actually superfluous leaves do not fall victim to the gardener's scissors, they usually remain on the trunk for the entire life of the palm, whereby the leaves form a spiral-shaped crown. Therefore, the crown of the Trachycarpus fortunei takes on an elongated shape without horticultural interventions, or rather, it appears spherical at the top and then tapers downwards and downwards, the older the leaves get, more and more towards the trunk tend.
The leaf sheath forms back into a network of fibers, which then merges into a dense network of long, coarse, dark brown, hairy threads. A long leaf-shaped appendix arises from the opening of the leaf sheath, which is divided into thin papyrus-like, brown strips 15 to 50 cm long, which appear in large numbers on the central shoot, hang down, and then unravel into hundreds of hemp-like threads. On the back of the leaf base, a triangular lignified part remains in the middle, which tapers towards the top and merges into the petiole (the petiole).
The petioles are 0.5 to 1.0 m long, with a more or less triangular cross-section, the top is smooth, the lower edge is strongly rounded; Width about 2 cm, from the base to the tip almost evenly wide and hardly enlarging at the base of the leaves, where on the upper side there is an almost woody, crescent-shaped tongue (ligula or hastula) or a crest with an irregular and serrated border, the petioles are sharp-edged on the sides and have pointed thorns or teeth over the entire length, which are of different sizes, especially towards the base, occur more often there, sometimes also look wart-shaped and point in opposite directions.
leaves
The crown is made up of up to 50 leaf fans or more. The top is dark green and only slightly shiny, the underside is often bluish-white frosted, especially with young leaves. The leaves have 40 to 50 segments, 50 to 90 cm long, measured from the hastula to the tip of the central segments. As a result, the leaf blade reaches a diameter of 90 to 160 cm and is split deeply by the segments in an irregular sequence, but every 2 or 3 leaf segments (sometimes 4) a much deeper incision to a depth of only 10 to 15 cm to the Hastula can be seen. The segments are sword-shaped, approx. 3 cm wide and only tapering towards the end, where they are cut about 2 to 4 cm deep, or slightly two-toothed, with short divergent tips. The lateral segments are much narrower, much shorter and taper more towards the segment tip. All leaf segments have a strong central rib on the underside, which arises at the petioles tip, but becomes thinner towards the segment tip. As many ribs arise on the upper side of the leaf, but they are not as pronounced as on the underside of the leaf, and which end in a kind of callus in the bulge between the individual segments at quite different distances (10 to 25 cm) from the hastula. Fine but nevertheless recognizable, closely meshed secondary nerves are almost equally visible at a distance of ½ mm from each other on both leaf sides.
The Trachycarpus fortunei is a fairly variable plant; on the one hand, due to its large geographical distribution area, there are numerous local variants, on the other hand this plant shows a considerable variance depending on the circumstances under which it is cultivated. In fact, one and the same plant in a sunny and dry place will develop a stocky trunk with short petioles and shorter, stiff and firm leaf segments. But if you transport the same plant to a cool, shady place, especially a sheltered place with light mainly from above, it will grow faster there, the fronds will form longer petioles, and the leaf segments will be longer and softer so that they will eventually be below hers Bend your own weight down. This variability had previously led to the view that there were two closely related, but nevertheless specifically distinguishable species, one of which is the true T. excelsa and the other the Trachycarpus fortunei . It was and is, however, impossible to find features distinguishing these two alleged species; It was also found that both “species” developed from the seeds of one and the same mother plant.
Inflorescences and flowers
This palm species is dioeciously separated sex ( diocesan ), rarely hermaphroditic.
The male inflorescences grow upright at first, then clearly curved and finally hanging down. They are 70 to 90 cm long, half of which consists of a thick stem, panicle-shaped, pyramidal, with three to four main branches. After flowering, they wither and dry out without falling off, so that the remains of the inflorescences of past years can often be found on intact plants. With large and strong palms, the stem reaches about the circumference of a wrist and is surrounded by three complete bracts ( spathe ).
The male inflorescences are covered with very dense, conspicuously yellow-colored flowers that secrete pollen. The female inflorescences are light green and less densely covered with flowers. After pollination, fruits only develop on the female inflorescences, unless there are also hermaphroditic flowers on the male inflorescences in addition to the male flowers.
The male flowers have tiny, small, transparent bracteoles (bracts). The flowers are yellow, fleshy and, during flowering, distantly spherical-triangular, about 3 mm in size. The sepals (sepals) are of different sizes, egg-shaped, tapering at the top, transparent at the edges and flawlessly smooth. The petals (petals) are broad and ovoid, twice as wide and much longer than the sepals, concave, blunt, smooth and not overlapping from the center upwards, below they overlap or interlock at the edges to the base of the flower: 6 equally large Stamens (stamen), with free-standing, fleshy, almost spindle-shaped stamens (filaments) that taper just below the tip and are as long as the petals. The anthers (anthers) are elongated-arrow-shaped, straight and upright (not bent inwards) before full bloom (anthesis). They sit in the middle of their underside on the filaments. They are flexible and deeply cut along the length, truncated at both ends and open at the sides. The flower has three carpels (carpels) of slightly conical shape, which are slightly curved and divergent. They are hairless and about half as long as the petals.
The female inflorescences are very similar to the male and fleshy. They are spread apart during flowering and later bent downwards after the fruit has ripened. The side branches are splayed and almost horizontal. The female flowers are greener than the male, but otherwise very similar. At the time of pollination it is spherical and about 2 mm in diameter, smooth and hairless.
The calyx is light green and has broad, egg-shaped and also fleshy and tapering sepals (sepals), which stand close together at the base and are also somewhat thickened there. They are smooth and rounded on the outside with thin edges, almost transparent. The petals are about a third longer than the sepals, almost circular, concave, the edges on the flower base slightly overlapping, at the tips the leaf edges touch without overlapping. The sepals are usually blunt at the top and the edges are sharp. There are six staminodes that are barely or about 1/3 shorter than the petals. The filaments appear somewhat compressed, tooth-shaped, and wearing sterile, but well-trained dust bags (anther), the almost as wide as long, dull and are arrow-shaped, strong spread the receptacle. Three carpels, separated from each other from the base of the flower and covered with silvery woolly hair, especially on the back. The carpels abruptly merge into a thick, conical stylus with a superficial furrow on the inside. The scar at the end of the stylus is papilous (warty). The ovules on the flower base are upright and directed downwards ( anatropic ).
Sometimes male Trachycarpus fortunei also have inflorescences with hermaphrodite flowers, which differ from the male flowers only in that they are a little larger and less close together. The carpels are also better developed than in male flowers and are hairy in the middle. The carpels are about the same size as the petals. The appearance of some hermaphroditic flowers on male inflorescences of Trachycarpus fortunei is not really uncommon because all male flowers have fairly well developed carpels anyway. In the case of the hermaphrodite flowers, however, just like the exclusively female flowers, these carpels are provided with a ring of fine, silvery hairs, which is located slightly below the center of the carpel. This ring is missing from the carpels of exclusively male flowers. Most of the carpels of the hermaphrodite flowers are equally well developed, but there are also some in which the ovule has prematurely lost or those that are partially open at the sides. The hairy ring of these carpels is missing, or you can only see their remains in the form of a small wart-shaped thickening. It is not uncommon for one of the three carpels to be only rudimentary . Cases have also been reported in which male flowers were found on some branches of one inflorescence and female flowers on the other side branches. There were also some hermaphrodite flowers (although apparently sterile) between the male flowers of the same inflorescence.
Hermaphrodite flowers can also appear on female inflorescences, which allows the female flowers to be pollinated.
Fruits and seeds
The ripe fruits are blue, kidney-shaped, smooth berries. The fruits are initially green, later yellowish, but when fully ripe they are blue-violet in color, somewhat like a blue grape, and just like this they have a waxy frosting. The fruits are round, kidney-shaped on the transverse side, longer than they are tall, 12 to 13 mm wide, 9 mm high and about as thick. The fruits and seeds are navel-shaped constricted on one side. The pericarp is quite thin at about 2/3 mm thick and the epicarp (seed coat) is thin as a film, shiny, brittle and easy to remove. The mesocarp is thin and dark purple, sweet in taste and fleshy when the fruit is fresh. The endocarp is firmly attached to the semen.
The seeds are slightly smaller than the fruit, but have exactly the same shape. They are about 11 mm wide, 7 mm high and 7 mm thick and have a deep notch on the navel side. The embryo is almost in the middle on the opposite side.
There may be peculiarities with pollination and fruit development. Since the flower of the Trachycarpus fortunei has three carpels, each of which is able to produce a seed, twin seeds or even triplets can sometimes arise, although the second and especially the third seed usually remains very small and does not develop completely. It can also lead to the development of "pseudo-fruits" that have the appearance of a clover leaf and are hollow. These pseudo-fruits can also arise when the carpels of the flowers have been pollinated with incompatible pollen .
Chromosome number
The number of chromosomes is 2n = 36.
Distribution and location
The Chinese hemp palm is native from the Himalayas in northern India to northern Thailand and the People's Republic of China . The true home of the Trachycarpus fortunei , however, seems to be in the subtropical regions of central and eastern China.
The Chinese hemp palm is one of the cold-resistant species, but it is also often found in Mediterranean gardens. In Europe it can be found in the entire Mediterranean area to the milder areas of Central Europe , such as Switzerland and Austria.
In Switzerland, the Chinese hemp palm was originally created as an ornamental plant. Meanwhile overgrown plants colonize forest clearings and other disturbed forest locations. Young trees cause a large amount of shading of the ground, so that native young plants are inhibited in their growth. In addition, it is worthless as a food source for birds and wild bees. Due to the displacement of the native vegetation, this plant was added to the black list of invasive neophytes in Switzerland. The first spontaneous occurrence was documented around 1920 near Gandria on Lake Lugano. The plant has been established in Ticino since the 1980s ; today it can also be found on the north shore of Lake Geneva , and in some cases in German-speaking Switzerland . In Ticino they are mainly found in forests, on the edges of forests and on shady roadsides. The spread is often associated with climate change. In Switzerland, the hemp palm can still be sold as an ornamental plant, but owners are encouraged to cut off the flower stocks in good time to prevent them from multiplying, and cut parts of the plant must be professionally composted (no garden compost). There is also a risk of invasive spread in the mildest regions of Germany. Overgrown young palm trees were found in six locations in Austria.
As an ornamental plant, the plant north of the Alps needs protection in colder winters. Without active protection (renovation, heating), severe leaf damage or total loss can occur. The cause for the death of the plants is falling below a minimum temperature with subsequent destruction of the meristem and / or drought damage due to permafrost. After pollination, adult female plants regularly produce seeds that mature and are fertile in December to January .
A species closely related to Trachycarpus fortunei is Trachycarpus takil from the Indian Himalayas west of Nepal (Kumaon region). Regarding the distinguishing features between these two species, reference is made to the description of Trachycarpus takil .
Forms and variations
Trachycarpus fortunei "wagnerianus" was described in 1915 by the botanist Odoardo Beccari as a new species under the name Trachycarpus wagnerianus , but is no longer considered an independent species in the genus Trachycarpus , but only as a synonym for Trachycarpus fortunei . Since no natural habitat has ever been found for this palm, ithybridizeseasily with Trachycarpus fortunei and differs from the latter only in its smaller leaves and slightly differently shaped flowers, this species was subsumed under Trachycarpus fortunei . The latest genetic analyzes have shown that the "Wagnerianus" can always be distinguished from Trachycarpus fortunei , but that the genetic distances are extremely small.
The "Trachycarpus wagnerianus" was originally brought to Europe by Albert Wagner, a horticulturalist from Leipzig . The "Wagnerianus" is a not so high growing horticultural cultivated form of Trachycarpus fortunei . The trunk is cylindrical and columnar, and covered with an equally dense network of fibers, as in Trachycarpus fortunei . The leaves are semicircular or almost ¾ circular, but much smaller than that of Trachycarpus fortunei . The leaves are almost evenly dark green on both leaf sides and deeply but irregularly divided into about 40, very stiff segments . The leaf segments are 40-45 cm long and each about 15 to 20 mm wide (rarely larger). At the tips they are segments easily divided into two or two-toothed. The petioles are slightly serrated at the edges at the base and ends, while the central part of the petioles has barely noticeable teeth. They are slightly convex on their upper side. The inflorescences are very similar to those of Trachycarpus fortunei , but they are more robust and solid. The male inflorescences have smooth branches that are less densely covered with flowers than in Trachycarpus fortunei . The "Wagnerianus" is as hardy as the Trachycarpus fortunei and has the same demands in terms of culture.
use
Trachycarpus fortunei is the most frequently cultivated species of the eight officially (according to Kew Gardens) recognized hemp palm species. It used to be an important crop because the tough fibers were processed into mats, ropes, brushes and even raincoats. The long-lasting, moisture-resistant trunk wood is also very much appreciated.
Care in Central Europe
The hemp palm can be planted well or stand as a container plant in the garden. A permeable and slightly acidic substrate should be used. Older specimens also tolerate pure garden soil . The hemp palm likes the sun; it grows more slowly in partial shade. Extensive watering in summer can stimulate growth, so that 15 cm trunk growth or more per year is also possible in our latitudes. However, fruiting female hemp palms grow more slowly than males. If it gets very cold outside (<-10 ° C) and wind is to be expected at the same time, the plant should either be protected from the wind (so that the leaves do not bend) or be placed in a bright, cool room as possible for the winter (under 5 ° C it can also be darker); the substrate should never dry out during hibernation. Palms overwintered outdoors are very frost-tolerant and, unlike many other frost-tolerant palms, the hemp palm is also very moisture-tolerant, as it is used to a lot of rainfall from its natural habitats . Long-term permafrost, even if the temperatures during the day may be positive, with deep ground frost, which prevents the roots from absorbing water, is far more dangerous than short-term very cold weather influences. A frequent problem is not the damage to the plant, much more so they dry up because no more water can be absorbed from the frozen ground, which is important for evergreen plants, as they also evaporate water in winter. Protective measures should be taken from around -10 ° C. Attempts to plant out have been successful in areas that can be assigned to winter hardiness zones 7b and 8a in recent years. At least in winter hardiness zone 7b, however, moisture or winter protection should be applied at lower temperatures.
In Switzerland, where the plant is considered an invasive neophyte , owners are encouraged to put a stop to any spontaneous spread (cutting off the inflorescences, professional composting), see also #Distribution and location .
Web links
- Description and identification key in the Flora of China (draft )
- Literature on Trachycarpus fortunei in the Kew Bibliographic Databases (English)
literature
- Odoardo Beccari: Le Palme del Genere Trachycarpus , Webbia 1, 1905
- Odoardo Beccari: Recensione delle palme del vecchio mondo . Webbia 5, 1920
- Odoardo Beccari: Asiatic Palms - Corypheae . Annals of the Royal Bot. Gard. Calcutta 13, Calcutta 1933
- Chris Stührk: Molecular systematic studies in the subtribe Thrinacinae, with special consideration of the genus Trachycarpus H. Wendl. (Arecaceae) , 2006.
- Carl Friedrich Philipp von Martius: Historia Naturalis Palmarum , Volume 3, 1850
Individual evidence
- ↑ a b The national data and information center for the Swiss flora: Hemp palm
- ↑ 20 minutes : Hemp palms threaten the Swiss forest , January 30, 2015, accessed on January 30, 2015
- ↑ Trachycarpus fortunei at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ https://www.wissenschaft.de/umwelt-natur/verwilderte-palmen-in-mitteleuropa/
- ↑ a b https://www.umweltnetz-schweiz.ch/themen/naturschutz/1763-invasive-neophyten-bedrohen-schweizer-w%C3%A4lder.html
- ^ Federal Office for the Environment FOEN: Invasive Alien Species . ( admin.ch [accessed on August 6, 2019]).
- ↑ S. Buholzer, M. Nobis, N. Schoenenberger, S. Rometsch: List of the alien invasive plants of Switzerland . Ed .: Infoflora. ( infoflora.ch [accessed on August 6, 2019]).
- ↑ Botanical Garden Bern: Exhibition Neophytes (Flyer)
- ↑ Basler Zeitung: Exotics grow between conifers and deciduous trees in Basel's forests , February 11, 2015
- ↑ Luzerner Zeitung: Canton of Zug: Palms grow wild in forests , accessed on July 30, 2017
- ↑ Die Welt: Exotic Ornamental Plants Threaten the German Forest , August 20, 2015
- ↑ Nadja Podbregar: Overgrown palm trees in Central Europe. In: Wissenschaft.de . July 31, 2019, accessed July 31, 2019 .