Oak mistletoe

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Oak mistletoe
Oak mistletoe (Loranthus europaeus), illustration

Oak mistletoe ( Loranthus europaeus ), illustration

Systematics
Eudicotyledons
Nuclear eudicotyledons
Order : Sandalwoods (Santalales)
Family : Belt flowers (Loranthaceae)
Genre : Loranthus
Type : Oak mistletoe
Scientific name
Loranthus europaeus
Jacq.

The oak mistletoe ( Loranthus europaeus ), also called belt mistletoe and belt flower , is a species of plant within the family of belt flower plants (Loranthaceae). It is common from Europe to West Asia. As a semi- parasite , like the white berry mistletoe ( Viscum album subsp. Album ), which is better known in the area, it parasitizes on the branches of deciduous trees. In contrast to this, however, mostly on oak species .

description

general characteristics

The oak mistletoe is a deciduous semi-parasitic plant. It draws some of the nutrients it needs, especially water and salts, from the host plants, into whose tissue it penetrates with its haustoria (suction organs). Due to the chlorophyll content of the leaves , it is capable of photosynthesis and can thus cover the need for carbohydrates itself.

The oak mistletoe grows as a spreading, richly forked-branched nanophanerophyte that reaches 0.30 to 1 meter in height. Roots are not developed, rather the species sits on its host plants in the form of a basal plate and from there lowers its haustoria via the wood tissue into the pathways of the host plant. These widen in the cambium and youngest xylem , but not in the phloem .

In contrast to those of mistletoe, its branches are barked brown, the fragile twigs are brown or black-gray. The shoots lignify very much.

Vegetative characteristics

Sheet view

The short-stalked, dark green and simple leaves are arranged opposite each other. They develop a length of 2–5 centimeters and a width of 1–2.5 centimeters. The veins are indistinctly pinnate. They are ovate to obovate and leathery in texture. They feel coarse and have a thickened epidermis. The leaf base is wedge-shaped to pointed and the tip is rounded to rounded. The leaf margin is entire. Stipules are absent. Unlike the evergreen white berry mistletoe , leaves are shed in autumn. There is no autumn color on the leaves.

Generative characteristics

Flowers of a male plant
A cut berry: You can see the very sticky substance in which a seed is embedded.

The oak mistletoe is dioecious, separate sexes ( diocesan ), this means that either only female or male flowers are formed on a plant. Sometimes hermaphroditic flowers are also developed in the oak mistletoe, but these are usually functionally male. This is due to the fact that after pollen has been emptied, the flowers wither quickly, so that hardly any fruit sets. In the case of oak mistletoe, the male individuals predominate in a ratio of 2: 1.

The small flowers are arranged in terminal inflorescences - the male, very short-lived flowers in loose clusters , the female eight to ten in loose spikes . The flowers of both sexes are radial symmetry with reduced organs of the opposite sex. Since there is no differentiation into calyx and crown, the flowers only have a simple flower envelope . However, an often undivided, weakly notched edge (calyculus) protrudes below the perigon around the base, which has been interpreted differently by authors. For example, it is interpreted as a calyx, a reduced calyx, an outgrowth of the axis or a cover sheet . A study from 2019, carried out using laser scanning and scanning electron microscopes , supports the hypothesis that the calyculus is derived from bracts or bracts and is therefore not to be interpreted as a calyx.

The inconspicuous yellow-green, slightly fleshy perigone can be four, rarely five or mostly six-fold pronounced. It is divided into lobes analogous to the number of tepals. The inner smooth tepals are in two circles and can develop a length of 2 to 4 millimeters.

The tepals of the male flowers are on average about 1 millimeter longer than those of the female flowers. The number of stamens corresponds to the number of tepals. The stamens are about two thirds of their length fused with the tepals. They have no narrowing below the anthers. Their length corresponds roughly to that of the tepals. The oval and immobile anthers are ivory in color and have two counters. These open through longitudinal gaps. In the female flowers, the stamens are in the form of staminodes . The subordinate, single-fan ovary is completely fused. It turns into a simple, straight stylus with a heady scar . The ovules are not differentiated, which is a typical degenerative phenomenon in parasitism. According to evolutionary studies, the ovule is reduced to a bare seed bud . Other authors tend to assume that the reduction has progressed further and that the embryo sacs develop directly in the placenta . The flowers of both sexes have nectaries at the base of the flower. The flowering period extends from April to June, depending on the region. It begins after the leaves shoot .

The fruits of the female specimens are 6 to 10 millimeters thick, smooth, golden yellow and solitary berries of ellipsoidal shape. Since the flower axis is involved in their formation, they are also known as false fruits or false berries. They are arranged opposite in the hanging fruit cluster. The pulp is very sticky. As hibernators , they stay on the branches in the cold season. In contrast to the mistletoe of the genus Viscum , the oak mistletoe is fruitful in autumn.

The number of chromosomes is 2n = 18.

Taxonomy

The species Loranthus europaeus was first scientifically described in 1762 by Nikolaus Joseph Freiherr von Jacquin in the work Enumeratio stirpium plerarumque, quae sponte crescunt in agro Vindobonensi . It belongs to the genus Loranthus , which includes 500 to 200 species depending on the genus conception . Most of them are native to the tropics and subtropics of the Old World ( Paleotropic ). In loranthus europaeus not been sub-species or varieties described. Also synonyms are unknown.

ecology

Infructescence in March

In contrast to the white berry mistletoe, which parasitizes extremely rarely on oak, the host spectrum of the oak mistletoe includes oak species and very rarely the sweet chestnut ( Castanea sativa ). Among the oak species that are parasitized are, for example, the pedunculate oak ( Quercus robur ), the sessile oak ( Quercus petraea ), the downy oak ( Quercus pubescens ), the red oak ( Quercus rubra ) and the Zerr oak ( Quercus cerris ). Occasionally, as a result of the host-parasite interaction, abnormal growths known as "wood roses" develop on the host plant.

pollination

The female flowers of the oak mistletoe are usually pollinated by insects that are offered nectar. The flowers are spread out flat so that even short-nosed insects can get to the nectar. Beetles , flies , syrphids , wasps and medium- nosed bees are typical pollinators . Bees of the genus Halictus appear particularly frequently . According to Müller's flower classes , the flowers are referred to as flowers with exposed nectar . Since male and female flowers are distributed among different individuals, self-pollination is impossible.

Spread

The seeds spread via digestive spread and Velcro spread . Birds often do the spreading of the seeds. The berries are eaten by birds such as mistletoe , fieldfare and waxwing , which means that the seeds can get onto branches of host plants after passing through the intestines. However, there are also birds that chop up and eat the seeds and thus counteract their spread.

Effects on the host plant

The decrease in wood growth can be between 20 and 50% depending on the amount of mistletoe. Oaks that are heavily infested with oak mistletoe can die.

Occurrence

The oak mistletoe occurs in Central , Eastern and Southeastern Europe as well as in Asia Minor . In the German-speaking area you can only find them in Austria and Germany.

The northern limit of distribution runs from the foot of the inner Carpathian arch to the northwest over the Ore Mountains and then ends in Pirna . In the west it populates Lower Austria and south of the Pos Italy including the northeast of Sicily . It is widespread on the Balkan Peninsula as in the Pannonian Basin. Its deposits reach Moldova and Dobruja, as well as the Crimean peninsula with an isolated deposit .

In Austria the mistletoe occurs very frequently in the Pannonian region and is increasing here. There are numerous occurrences, especially in the Danube Valley. Otherwise they are only found scattered or very rarely. The occurrences are limited to the colline to submontane altitude level of the federal states of Vienna , Burgenland , Lower Austria , Styria and Upper Austria . In the northern foothills of the Alps, the oak mistletoe is considered endangered.

In Germany, the oak mistletoe is rarely found in Saxon Switzerland .

The oak mistletoe needs summer warmth and rather dry air to thrive.

Ingredients and use

In addition to various sugars, the fruits of the oak mistletoe also contain rubber . It is particularly found in the fleshy shell, the former flower axis, and in the endocarp . The rubber ensures that the slime retains its sticky consistency even after drying. In the past, the berries of the oak mistletoe were used to make a tough bird glue , which was used to coat rods that were used to catch birds. Mistletoe, especially the one that grows on oak trees, was mentioned as effective against magic and diseases as early as ancient mythology. In the late Middle Ages and beyond, the oak mistletoe tract, which originated in southern Germany in the 14th century and recommends mistletoe as a miracle drug for the prevention of seizures, was widespread nationwide.

photos

Other species of the genus

Another species in the genus is Loranthus kayseri , named after Emanuel Kayser . It can be found in coastal regions of Kenya and Tanzania .

literature

  • Annelore Högemann: The old German 'oak mistletoe tract'. Investigations into a Bavarian drug monograph from the 14th century (= Medieval wonder drug tracts. 2). Wellm, Pattensen; now Königshausen & Neumann, Würzburg 1981 (= Würzburg medical-historical research. Volume 19), (At the same time: Würzburg, Univ., dissertation 1981). ISBN 3-921456-25-8 .
  • Willem Frans Daems , Gundolf Keil : The mistletoe tract of the Vienna Codex 3811. In: Sudhoffs archive. Volume 49, 1965, ISSN  0931-9425 , pp. 90-93.
  • Christian Probst : The old German oak mistletoe tract in a Baier text witness from the late 18th century. In: light of nature. Medicine in specialist literature and poetry: Festschrift for Gundolf Keil on his 60th birthday. Göppingen 1994 (= Göppinger works on German studies. Volume 585), pp. 293-305.
  • Stephan Endlicher : The Medicinal Plants of the Austrian Pharmacopoeia. Gerold, 1842, p. 407 ff.
  • Gustav Hegi : Illustrated flora of Central Europe . III. Volume, JF Lehmanns, 1912, pp. 145, 149 f.

Web links

Commons : Oak mistletoe ( Loranthus europaeus )  - album with pictures, videos and audio files

Individual evidence

  1. This name is ambiguous, as Viscum album also very rarely parasitizes on oaks and specimens of this kind, which are supposed to be particularly medicinal, are called "oak mistletoe".
  2. a b c d e f g h i j Denes Bartha: Loranthus europaeus. In: Encyclopedia of Woody Plants: Handbook and Atlas of Dendrology. Wiley ‐ VCH Verlag, Weinheim 2014, ISBN 978-3-527-67851-8 , doi: 10.1002 / 9783527678518 .
  3. a b c d e f g h Ruprecht Düll , Irene Düll: Pocket dictionary of the Mediterranean flora. Quelle & Meyer, Wiebelsheim 2007, ISBN 978-3-494-01426-5 , p. 200 f.
  4. a b Oak mistletoe . In: BiolFlor, the database of biological-ecological characteristics of the flora of Germany.
  5. ^ A b Peter Schütt , Hans Joachim Schuck, Bernd Stimm: Lexicon of tree and shrub species . Nikol, Hamburg 2002, ISBN 3-933203-53-8 , pp. 278 .
  6. a b c d e f g h i j k l m Roland Aprent: A contribution to the current distribution of Loranthus europaeus in Styria. (PDF; 16.9 MB), In: Joannea Botany. 14, 2017, pp. 5–24.
  7. ↑ Oak mistletoe. In: FloraWeb.de.
  8. a b c d e Eckehart J. Jäger: Rothmaler - Exkursionsflora von Deutschland. Vascular plants: baseline. 21st edition, Springer, Berlin 2017, ISBN 978-3-662-49707-4 , pp. 554, 887.
  9. Thomas Pecher: Mistletoe and European belt flower. Settlement of semi-parasitic wild trees in the natural garden. In: Natur & Garten , April 2009, pp. 51–53.
  10. a b c d Loranthus europaeus L. - Eichenmistel, Riemenblume ( Memento from September 30, 2007 in the Internet Archive ).
  11. Edith Rebecca Saunders : Floral Morphology. 2nd Volume, Chemical Publishing Company, 1940, p. 344.
  12. a b c Ruozhu Lin, Bei Cui, Wenxia Zhao: The Origin and Identity of the Calyculus in Loranthaceae: Inferred From the Floral Organogenesis of Loranthus tanakae Franch. & Sav. In: Phyton. Volume 88, No. 3, 2019, pp. 285-293, doi: 10.32604 / phyton.2019.07182 .
  13. ^ Wilhelm Hofmeister : New contributions to the knowledge of the embryo formation of the phanerogams. 1. Volume, Hirzel, 1859, pp. 539-542, Plates I-IV, online at biodiversitylibrary.org.
  14. Soror Imelda Mayr: About the germination and first development of the belt mistletoe (Loranthus europaeus Jacq.). Botanical Institute of the University of Innsbruck, 1928.
  15. ^ Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas. 8th edition, Verlag Eugen Ulmer, Stuttgart 2001, ISBN 3-8001-3131-5 . P. 325.
  16. Entry Loranthus europaeus at IPNI
  17. Oak mistletoe near the Donau-Auen National Park.
  18. The Euro + Med PlantBase - the information resource for Euro-Mediterranean plant diversity . , accessed January 5, 2014.
  19. ^ Manfred A. Fischer, Karl Oswald, Wolfgang Adler: Excursion flora for Austria, Liechtenstein and South Tyrol . 3rd, improved edition. Province of Upper Austria, Biology Center of the Upper Austrian State Museums, Linz 2008, ISBN 978-3-85474-187-9 , p. 388 .
  20. Dietmar Aichele, Heinz-Werner Schwegler: The flowering plants of Central Europe . 2nd Edition. tape 3 : Evening primrose plants to reddish plants . Franckh-Kosmos, Stuttgart 2000, ISBN 3-440-08048-X .
  21. Gerhard Wagenitz (Ed.): Gustav Hegi: Illustrated Flora of Central Europe. Volume III, Part 1, 3rd Edition, Paul Parey, Berlin / Hamburg 1981; quoted in Roland Aprent: A contribution to the current distribution of Loranthus europaeus in Styria. (PDF; 16.9 MB), In: Joannea Botany. 14, 2017, p. 7.
  22. Karl Adam Heinrich von Bose: New general practical dictionary of hunting science . JT Hinrichs, Leipzig 1810, p. 300 ( oak mistletoe on p. 300 in the Google book search).
  23. Wolfgang Wegner: Oak mistletoe tract. In: Werner E. Gerabek , Bernhard D. Haage, Gundolf Keil, Wolfgang Wegner (eds.): Enzyklopädie Medizingeschichte. De Gruyter, Berlin / New York 2005, ISBN 3-11-015714-4 , p. 337 f.
  24. JSTOR: Global Plants: Loranthus kayseri , ITHAKA, accessed on August 23, 2020
  25. JSTOR: . Loranthus Kayseri Engl [family Loranthaceae]. ITHAKA, accessed August 16, 2020 .