Poa annua
{{Short description|Species of plant}}
{{Speciesbox
|image = poa_annua.jpeg
|status = LC
|status_system = IUCN3.1
|genus = Poa
|species = annua
|authority = L.
}}
Poa annua, or annual meadow grass (known in America more commonly as annual bluegrass or simply poa), is a widespread low-growing turfgrass in temperate climates. Notwithstanding the reference to annual plant in its name, perennial bio-types do exist.{{Cite book |last1=Jr |first1=J. M. Vargas |url=https://books.google.com/books?id=PtnRMlhbbaoC&dq=Poa+annua+annual+and+perennial+biotype&pg=PP9 |title=Poa Annua: Physiology, Culture, and Control of Annual Bluegrass |last2=Turgeon |first2=Alfred J. |date=2003-12-19 |publisher=John Wiley & Sons |isbn=978-0-471-47268-1 |language=en}} This grass originated as a hybrid between Poa supina and Poa infirma.Collins pocket guide Grasses, Sedges, Rushes and Ferns. Fitter.R, Fitter.A, Farrer.A. 1995. page 54 Major chromosomal rearrangements after polyploidy have contributed to variation in genome size in Poa annua.{{Cite journal |last1=Benson |first1=Christopher W. |last2=Sheltra |first2=Matthew R. |last3=Maughan |first3=Peter J. |last4=Jellen |first4=Eric N. |last5=Robbins |first5=Matthew D. |last6=Bushman |first6=B. Shaun |last7=Patterson |first7=Eric L. |last8=Hall |first8=Nathan D. |last9=Huff |first9=David R. |date=2023-06-26 |title=Homoeologous evolution of the allotetraploid genome of Poa annua L |journal=BMC Genomics |volume=24 |issue=1 |pages=350 |doi=10.1186/s12864-023-09456-5 |issn=1471-2164 |pmid=37365554 |pmc=10291818 |doi-access=free }}
Description
It has a slightly creeping, fibrous, rootstock. The stem grows from 15–25 cm (6-10 in.) high. It is slightly flattened, due to being folded rather than rolled.
The panicle is open and triangular shaped, 5 to 7.5 cm (2 to 3 in.) long. The spikelets are stalked, awnless, 1 to 2 cm (3/8 to 3/4 in.) long when flowering, and loosely arranged on delicate paired or spreading branches. Sometimes they are tinged purple.
The vivid green leaves are short and blunt at the tips, shaped like the prow of a small canoe. They are soft and drooping. Long sheaths clasp the stem. The leaves are smooth above and below, with finely serrated edges. Occasionally the leaves are serrated transversely.
The ligule is pointed and silvery. Compared this to Common Meadowgrass Poa pratensis, which has a squared ligule, and Poa trivialis, which has a pointed, but less silvery ligule.
The leaves are smooth above and below, with finely serrated edges. Occasionally the leaves are serrated transversely.
It is in flower all year around except for severe winters. The seeds ripen and are deposited 8 months of the year. The plant grows rapidly from seed, flowering within 6 weeks, seeding and then dying.[http://www.bsbi.org.uk/identification.html BSBI Description] {{webarchive|url=https://web.archive.org/web/20110717004923/http://www.bsbi.org.uk/identification.html |date=2011-07-17 }} retrieved 10 December 2010.
Etymology
Poa is derived from the Greek name for a type of fodder grass.Gledhill, David (2008). "The Names of Plants". Cambridge University Press. {{ISBN|9780521866453}} (hardback), {{ISBN|9780521685535}} (paperback). pp 50, 308 Annua is Latin, meaning 'annual' or 'lasting a year'.
Distribution and habitat
It is a common weed of cultivation, known in the Americas as annual bluegrass.{{cite web
| last =Ohlendorf
| first =B.
|author2=D. W. Cudney |author3=C. L. Elmore |author4=V. A. Gibeault
| title =Annual Bluegrass Management Guidelines--UC IPM
| publisher =University of California
| date =April 2003
| url =http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7464.html
| access-date =2007-09-08 }} It occurs as a common constituent of lawns, where it is also often treated as a weed, and grows on waste ground. Many golf putting greens, including the Oakmont Country Club greens, are annual bluegrass,{{cite news| url=http://www.post-gazette.com/pg/07164/793591-382.stm | work=Pittsburgh Post-Gazette | title=Oakmont-inspired Stimpmeter allows USGA to accurately measure speed, consistency of putting surfaces | first=Robert | last=Dvorchak | date=2007-06-13}} although many courses have converted to creeping bentgrass (Agrostis stolonifera).
It has appeared on King George Island in the Antarctic South Shetland Islands as an invasive species,[https://www.economist.com/blogs/babbage/2012/03/antarctic-ecology Antarctic ecology: Polar invaders], The Economist, Mar 6th 2012 as well as on Australia's subantarctic Heard and Macquarie Islands.
{{Commons|Poa annua}}
{{Wikispecies|Poa annua}}
Poa annua.jpg|Habit
Straatgras tongetje (Poa annua ligula).jpg|Ligule is silvery and pointed.
Poa.annua.jpg|The panicle is open and triangular shaped
Poa.annua.2.jpg|Flowers
Poa annua on a footpath. 24 Oktoberplein, Utrecht, The Netherlands, May 20, 2018.jpg|Clump of Poa annua on footpath stones
References
{{Reflist}}
External links
- [http://poa.ipk-gatersleben.de European Poa Database]
- The Observers Book of Grasses, Sedges and Rushes. Frances Rose. pages 38–39
- [http://www.kew.org/data/grasses-db/ Kew gardens grass database]
- Weeds friend or foe? Sally Roth. pages 86–87
- [https://web.archive.org/web/20110717004923/http://www.bsbi.org.uk/identification.html BSBI Description]
{{Taxonbar|from=Q157571}}
{{Authority control}}
Category:Flora of temperate Asia
Category:Flora of tropical Asia
Category:Garden plants of Europe
Category:Plants described in 1753
Category:Taxa named by Carl Linnaeus