Large two-leaf

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Large two-leaf
Large two-leaf (Listera ovata)

Large two-leaf ( Listera ovata )

Systematics
Order : Asparagales (Asparagales)
Family : Orchids (orchidaceae)
Subfamily : Epidendroideae
Tribe : Neottieae
Genre : Two-leaf ( Listera )
Type : Large two-leaf
Scientific name
Neottia ovata
( L. ) Bluff & Fingerh.

The Twayblade ( Neottia ovata , Syn. : Listera ovata ) is a species of the genus two-sheet ( Listera ) within the family of orchids (Orchidaceae).

In order to draw attention to the need for protection of this inconspicuous species, the large two-leaf was chosen by the local orchids working group as the orchid of the year 1992 .

description

Illustration from Album des orchidées de l'Europe centrale et septentrionale , 1899
Detail of an inflorescence with a zygomorphic flower; the glands on the inflorescence axis are also clearly visible

Vegetative characteristics

The large two-leaf is a perennial herbaceous plant that reaches heights of 20 to 50 centimeters. with a short, rolling rhizome formed from several annual segments . The roots are fleshy and mostly creeping horizontally.

As a rule, there are only two leaves on a plant specimen, which are arranged almost opposite one another. In the bud position they are rolled up, thus showing "convolute vernation ". The simple, entire leaf blade is approximately egg-shaped with a length of 5 to 15 centimeters and a width of 3 to 8 centimeters.

Generative characteristics

The flowering period extends from May to July. A one-sided racemose inflorescence contains 20 to 40 flowers. The hermaphrodite, zygomorphic flowers are threefold and have no spur. The bracts are yellow-green.

The capsule fruits contain numerous, tiny seeds .

The number of chromosomes is 2n = 34 or 36-40.

ecology

The large two-leaf is a rhizome - geophyte . A vegetative reproduction occurs through the unusual process of the transformation of roots into sprouts. There is an orchid-type mycorrhiza . The plant feeds at least temporarily on the root fungus (myco-heterotrophy).

From an ecological point of view, it is "orchis-type lip flowers". The nectar secretion takes place on the runny lower lip and at the lip base. The inflorescence axis has sticky glandular hairs that repel insects creeping up. The dust bags lie on the rostellum and have no adhesive disc. When touching the rostellum tip, as an organ for the pollinia , it gushes explosively viscous mucus, so-called "glue drops", which attach the pollinia to the visitors. The pollination is done by parasitic wasps and beetles . Self-pollination (autogamy) occurs very rarely, cross- pollination (allogamy) is the rule. The large double leaf is accessible to a very wide range of pollinators, which explains the very high fruit set of 88% on average. The visitors often stay on the same plant specimen for a long time, which causes a high proportion of neighboring pollination (geitonogamy).

The seeds spread as wind spreaders and granular flyers.

Habitus in the habitat

Occurrence

The large two-leaf is a Eurasian plant species. Its area extends westward to Iceland , England and Spain , southward to Sicily , Crete and Turkey and eastward to the Altai and northwestern Himalayas . In Central Europe it occurs scattered, in the western lowlands it is absent in some areas. In its growing locations it often occurs in very loose, few individuals, but occasionally also in dense stands.

The large two-leaf grows best on base-rich clay or loam soils .

Fresh deciduous forests, meadows , grasslands and flat moors are preferred as locations . The large double leaf has a broad ecological amplitude. It populates deciduous forests, less often light coniferous forests or alluvial forests, in the mountains it also goes into moist meadows and the scrub accompanying streams; on the other hand, it often grows in dry grasslands in the limestone low mountain ranges . In semi-arid grassland societies (mesobromion) it is regarded as a clay soil and fresh freshness pointer , in pipe grass-pine societies and pipe grass meadows as a lean pointer . In the black alder-ash forest (Pruno-Fraxinetum) it is a companion plant .

In the Allgäu Alps, it rises at the summit of the Kanzelwand in Bavaria to an altitude of 2050 meters. According to Baumann and Künkele , the species has the following altitude limits in the Alpine countries: Germany 10-1900 meters, France 0-2500 meters, Switzerland 390-2300 meters, Liechtenstein 430-1950 meters, Austria 120-2100 meters, Italy 10-2300 meters, Slovenia 50-1490 meters. In Europe the species rises up to 2500 meters, in the Himalayas up to 3000 meters above sea level.

Picture gallery

  • inflorescence

  • Habit with flower buds

  • Listera ovata
    the large "trefoil",
    a deviation from the usual.

  • Listera ovata
    twin flower

  • Flower with pollinator

  • Single flower

swell

literature

  • Manfred A. Fischer, Wolfgang Adler, Karl Oswald: Excursion flora for Austria, Liechtenstein and South Tyrol . 2nd, improved and enlarged edition. State of Upper Austria, Biology Center of the Upper Austrian State Museums, Linz 2005, ISBN 3-85474-140-5 .
  • Dankwart Seidel: Flowers. Determine accurately with the 3-check. 2nd, revised edition. blv, Munich / Vienna / Zurich 2001, ISBN 3-405-15766-8 .

Individual evidence

  1. ^ The Plant List. Retrieved June 3, 2020 .
  2. ^ Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas. 8th edition. Stuttgart, Verlag Eugen Ulmer, 2001, page 273. ISBN 3-8001-3131-5 .
  3. ↑ a b c d Ruprecht Düll , Herfried Kutzelnigg : Pocket dictionary of plants in Germany and neighboring countries. The most common Central European species in portrait . 7th, corrected and enlarged edition. Quelle & Meyer, Wiebelsheim 2011, ISBN 978-3-494-01424-1 , p. 465 .
  4. ^ A b Jean Claessens, Jacques Kleynen: The flower of the European orchid. Form and function . Self-published, Geulle 2011, ISBN 978-90-90-25556-9 (English).
  5. ^ A b c Siegfried Künkele, Helmut Baumann: Orchidaceae. In: Oskar Sebald, Siegmund Seybold, Georg Philippi, Arno Wörz (eds.): The fern and flowering plants of Baden-Württemberg . tape 8 : Special part (Spermatophyta, subclasses Commelinidae part 2, Arecidae, Liliidae part 2): Juncaceae to Orchidaceae . Eugen Ulmer, Stuttgart (Hohenheim) 1998, ISBN 3-8001-3359-8 , Listera ovata , p. 324-326 .
  6. ↑ a b c Dietmar Aichele, Heinz-Werner Schwegler: The flowering plants of Central Europe . 2nd Edition. tape 5 : Swan flowers to duckweed plants . Franckh-Kosmos, Stuttgart 2000, ISBN 3-440-08048-X , p. 160 .
  7. ↑ Erhard Dörr, Wolfgang Lippert : Flora of the Allgäu and its surroundings. Volume 1, IHW, Eching 2001, ISBN 3-930167-50-6 , p. 394.
  8. ↑ a b Helmut Baumann , Siegfried Künkele : Orchidaceae . In: Oskar Sebald u. a .: The fern and flowering plants of Baden-Württemberg . 1st edition Volume 8, page 326. Verlag Eugen Ulmer, Stuttgart 1998. ISBN 3-8001-3359-8

Web links

Commons : Large two-leaf ( Listera ovata )  album with pictures, videos and audio files