Annual bluegrass ( Poa annua)
The Annual bluegrass ( Poa annua) is probably the most widespread and common sweet grass at all. While the other members of the genus of bluegrasses ( Poa ) herbaceous plants are perennial, this plant is perennial, but it can also overwinter under favorable circumstances.
The Annual bluegrass grows as annual herbaceous plant, forming small clumps, which have a comparatively small size with growth heights of 5 to a maximum of 30 cm, but usually 10 to 15 cm. The stems are prostrate, then ascending with some wrinkles to the Halmknoten. Be able to form roots at the nodes ( more nodes ). The light green to green leaves are 2-5 mm wide and have a short, characteristic boat-shaped tip.
The loosely spread, sometimes einseitswendigen paniculate inflorescences are rarely more than 5 cm. The panicle branches are often in pairs. The spikelets are four or mehrblütig, 2-5 mm long, green or purple rarely crowded. The lower glume is einnervig, the top three annoying. The panicles are formed if the weather throughout the year.
The Annual bluegrass is a ( sommerannueller ) or winterannueller Therophyt or a perennial plant Horst
The flowers are self-pollination and wind pollination after the " Langstaubfädigen type". The type has no Blühperiodizität and is therefore also a snow flowering. Annuals of the kind can flower after 45-60 days.
The fruits are available all year maturing caryopses, which are surrounded by the permanent, stiff hairy husks; they are only 0.2-0.4 mg hard. There is usually spread occurs (as Misty water ) that takes place next to people spreading, spread as wind spreader and balloonists, random dispersal by birds, digestive spread by ungulates and ants spread eg by pavement ants. The caryopses are light to germinate. Fruit ripening begins in May.
When annuals bluegrass is a cosmopolitan nature, being mainly grows in the tropics in the mountains. It is one of the few flowering plants that also occur in the Antarctic, but here only since a few decades.
The Annual bluegrass comes from lowlands to high mountains along roadsides, in pavement cracks, gardens, fields, meadows often occurs everywhere. She is the kind of character of impact grass communities ( Polygono - Poetea ). She loves nitrogen- rich heavy soil, but also grows in sandy soil. They are found in inner cities as well as in natural areas.
From the cattle Annual bluegrass is not eaten because of its small size, as long as high growing forage crops are present. On pastures his presence indicated thus indicate a overgrazing.
Thomas Gaskell Tutin has discovered through genetic testing that the Annual bluegrass is a allotetraploide kind infirma from Poa Poa and supina arose.
- Henning Haeupler, Thomas Muer: Image Atlas of ferns and flowering plants in Germany. Published by the Federal Agency for Nature Conservation Germany. Verlag Eugen Ulmer, Stuttgart 2000, ISBN 3-8001-3364-4
- Werner Rothmaler: Exkursionsflora the territories of the GDR and the FRG. Volume 2: vascular plants, 14th edition. Volk und Wissen, Berlin 1988, ISBN 3-060-12539-2.
- Otto Schmeil, Jost hinge plates, Werner Rauh: Flora of Germany and its neighboring areas. 84th edition. Quelle & Meyer, Heidelberg 1968.
- Dietmar Aichele, Heinz -Werner Schwegler: Our grasses. 7th edition. Franckh'sche Verlagsbuchhandlung, Cosmos naturalist guide, Stuttgart 1984, ISBN 3-440-05284-2.
- Grassland online - overgrazing.
- Guanghua Zhu, Liang Liu, Robert J. Soreng & Marina V. Olonova: Poa annua in the Flora of China, Volume 22, 2006, p 263: Online.
- Annual bluegrass. In: FloraWeb.de.
- Ruprecht Duell, Herfried Kutzelnigg: Pocket Dictionary of Plants in Germany and neighboring countries. The most common central European species in the portrait. 7, corr. and ext. Edition. Quelle & Meyer, Wiebelsheim 2011, ISBN 978-3-494-01424-1.