Compressed bluegrass

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Compressed bluegrass
Compressed bluegrass (Poa compressa), illustration

Compressed bluegrass ( Poa compressa ), illustration

Systematics
Commelinids
Order : Sweet grass (Poales)
Family : Sweet grasses (Poaceae)
Subfamily : Pooideae
Genre : Bluegrass ( Poa )
Type : Compressed bluegrass
Scientific name
Poa compressa
L.

The compressed panicle grass ( Poa compressa ), also known as platthalmrispe or flat panicle grass , is a widespread sweet grass (Poaceae). A special feature of this plant are its hollow, laterally flattened and thus oval stems, to which the specific epithet compressa refers.

Distribution and location

The compressed bluegrass is widespread from Europe to western Siberia and from the Mediterranean area with North Africa to China. It occurs from the lowlands to altitudes of 1860 m (Alps). It was introduced to North America and is known there as "Canada Bluegrass". In Germany the grass occurs scattered to often. It is missing in parts in the north. It grows mainly in pioneering societies on dams, on walls, in gravel pits, on rubble sites and on paths on open, dry and poor, mostly lime-rich, but poorly humus and fine earth, sand, gravel and stone soils.

According to Ellenberg , it is a full-light plant, distributed sub-oceanic, prefers a dry pointer, a base and calcareous pointer, low-nitrogen locations. The compressed bluegrass is also an order character of semi-rudder pioneer and semi-arid lawns (Elymetalia (= Agropyretalia) repentis) and comes e.g. B. in the Poo-Tussilaginetum or in the Poetum ancipiti-compressae. But it also thrives in the society of the order Corynephoretalia.

Stem with compressed, keeled leaf sheath and ligule
Double-grooved leaves
Compressed bluegrass ( Poa compressa ), inflorescence
Compressed bluegrass ( Poa compressa ), inflorescence
Spikelets

features

The compressed bluegrass is a stiff and gray-green, perennial plant that reaches heights of between 10 and 40, sometimes up to 70 centimeters. The deciduous hemicryptophyte grows loosely clumpy and spreads over wiry rhizomes . The smooth and laterally compressed and thus oval cross-section stalks grow kinky and ascending from the base. They wear four to six knots . The smooth leaf sheaths are also compressed, keeled and therefore double-edged. The white ligules are blunt and 0.5 to 4 millimeters long. The rigid leaf blades are narrow, linear, rough on top and tapering into a hood-shaped tip. Next to the leaf rib there is a channel (ski track). The leaves reach less than 6 centimeters in length. The leaf base is always unlashed.

The inflorescences are compact, narrow pyramidal panicles . These measure 1.5 to 10 centimeters in length and between 0.5 and 3 centimeters in width. They are colored green, yellow-green or purple. The slightly angular and rough panicle branches are in pairs or clusters. The three- to ten-flowered, up to 8 millimeter long spikelets are in turn tightly tufted on the panicle branches. They are egg-shaped to elliptical in shape and compressed. All husks are not awned , keeled and rough on the keels. The three-veined glumes are somewhat unevenly shaped. The lemmas are indistinctly five-nerved, glabrous, weakly hairy or sometimes woolly hairy on the base. The caryopses are tightly enclosed by the hardened cover and palea. The flowering period extends from June to August.

The number of chromosomes is 2n = 35, 42, 45, 49, 50, 56.

Systematics

There are two subspecies:

  • Poa compressa subsp. compressa  : spikelets 3-6 (-7) -flower.
  • Poa compressa subsp. langiana (Rchb.) Hegi (as species: Poa langiana Rchb. ): This subspecies, which is distinguished by 7-11-flowered spikelets and non-hairy lemmas, was previously only known from the Isteiner Klotz in southern Baden-Württemberg. She is missing today.

ecology

The compressed bluegrass is a perennial hemicryptophyte (including two-year-olds) and a creeping pioneer . The seeds spread through the wind as balloon fliers, and reproduction by apomixis has also been proven. Vegetative reproduction occurs through underground runners.

Use, exposure and status

In Central Europe it is of no importance as forage or pasture grass, but can be used for the grassing of dry slopes. The compressed bluegrass is not endangered in Europe and does not enjoy any special legal protection ( CITES , Bern Convention , BArtSchV ).

In North America the grass has some value as pasture grass on poor and arid soils. In some states of the United States, especially Wisconsin , the grass is considered an invasive or potentially invasive species ( Virginia , New England ). For example, it invades prairies and other natural or renatured grasslands. Due to its vigorous rhizome growth and the effective seed dispersal, negative effects on the natural composition of species (displacement of the native flora) as well as other direct and indirect ecological effects on communities or biotopes are feared.

Sources and further information

Single sources

  1. ↑ Rafaël Govaerts (ed.): Poa compressa. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved November 12, 2016.
  2. ↑ a b c Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . 8th edition. Stuttgart, Verlag Eugen Ulmer, 2001. ISBN 3-8001-3131-5 . Page 225.
  3. ↑ Wisconsin Department of Natural Resources ( Memento of the original from May 2, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / dnr.wi.gov
  4. ↑ Invasive Plant Atlas of New England ( Memento of the original from September 10, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.lib.uconn.edu
  5. ↑ Invasive Alien Plant Species of Virginia

literature

  • Henning Haeupler , Thomas Muer: picture atlas of the fern and flowering plants of Germany (= the fern and flowering plants of Germany. Volume 2). Published by the Federal Agency for Nature Conservation. Ulmer, Stuttgart 2000, ISBN 3-8001-3364-4 .
  • CE Hubbard: Grasses - Description, Distribution, Uses. Ulmer Verlag, Stuttgart 1985, ISBN 3-8001-2537-4
  • E. Oberdorfer: Plant-sociological excursion flora. Ulmer, Stuttgart 1994, ISBN 3-8252-1828-7
  • Wilhelm Opitz von Boberfeld , Ernst Klapp: Pocket book of grasses. Recognition and determination, location and socialization . Ulmer Verlag, Stuttgart 2006, 13th revised edition, ISBN 3-8001-4775-0
  • Schmeil-Fitschen: The flora of Germany interactive, ISBN 3-494-01368-3
  • Heinz Ellenberg : Vegetation of Central Europe with the Alps from an ecological, dynamic and historical perspective. 5th, heavily changed and improved edition. Ulmer, Stuttgart 1996, ISBN 3-8001-2696-6 .

Web links

Commons : Compressed bluegrass  album with pictures, videos and audio files

Pictures: [1] [2] Platthalm-Rispengras ( Memento of October 15, 2006 in the Internet Archive ) [3]