''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 In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ra ...

. Notwithstanding the reference to

annual plant An annual plant is a plant that completes its life cycle, from germination to the production of seeds, within one growing season, and then dies. Globally, 6% of all plant species and 15% of herbaceous plants (excluding trees and shrubs) are ...

in its name,

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

bio-types do exist. This grass originated as a

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

between '' Poa supina'' and ''

Poa infirma ''Poa infirma'' is a species of grass known by the common names early meadow-grass and weak bluegrass. It was first described from a specimen found in Colombia, but it is actually an introduced species in the Americas and is native to Europe. It ...

''. Major

chromosomal rearrangements A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most importa ...

after

polyploidy Polyploidy is a condition in which the cells of an organism have more than two paired sets of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one fro ...

have contributed to variation in

genome size Genome size is the total amount of DNA contained within one copy of a single complete genome. It is typically measured in terms of mass in picograms (trillionths or 10−12 of a gram, abbreviated pg) or less frequently in daltons, or as the tot ...

in ''Poa annua''. Poa annua in urban areas

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 In botany, a panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a p ...

is open and triangular shaped, 5 to 7.5 cm (2 to 3 in.) long. The

spikelet A spikelet, in botany, describes the typical arrangement of the inflorescences of grasses, sedges and some other monocots. Each spikelet has one or more florets. The spikelets are further grouped into panicles or spikes. The part of the sp ...

s 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 The bow () is the forward part of the hull (watercraft), hull of a ship or boat, the point that is usually most forward when the vessel is underway. The aft end of the boat is the stern. Prow may be used as a synonym for bow or it may mean the f ...

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 A ligule (from "strap", variant of ''lingula'', from ''lingua'' "tongue") is a thin outgrowth at the junction of leaf A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above g ...

is pointed and silvery. Compared this to Common Meadowgrass ''

Poa pratensis ''Poa pratensis'', commonly known as Kentucky bluegrass (or blue grass), smooth meadow-grass, or common meadow-grass, is a perennial species of grass native to practically all of Europe, North Asia and the mountains of Algeria, Morocco, and Tuni ...

'', which has a squared ligule, and ''

Poa trivialis ''Poa trivialis'' (rough bluegrass; ''UK:'' rough-stalked meadow-grass or rough meadow-grass), is a perennial plant regarded in the US as an ornamental plant. It is part of the grass family. Description It is very common in meadows and pasture ...

'', 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.

Etymology

''Poa'' is derived from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

name for a type of fodder grass.Gledhill, David (2008). "The Names of Plants". Cambridge University Press. (hardback), (paperback). pp 50, 308 ''Annua'' is Latin, meaning 'annual' or 'lasting a year'.

Distribution and habitat

It is a common

weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...

of cultivation, known in the Americas as annual bluegrass. It occurs as a common constituent of

lawn A lawn () is an area of soil-covered land planted with Poaceae, grasses and other durable plants such as clover lawn, clover which are maintained at a short height with a lawn mower (or sometimes grazing animals) and used for aesthetic an ...

s, where it is also often treated as a weed, and grows on waste ground. Many golf

putting green A golf course is the grounds on which the sport of golf is played. It consists of a series of holes, each consisting of a tee box, a fairway, the rough and other hazards, and a green with a cylindrical hole in the ground, known as a "cup". T ...

s, including the

Oakmont Country Club Oakmont Country Club is a golf course country club which, despite its name, is mostly located within the borough of Plum, Pennsylvania with only a small portion of the property actually in the small town of Oakmont. Established in 1903, the club ...

greens, are annual bluegrass, although many courses have converted to

creeping bentgrass ''Agrostis stolonifera'' (creeping bentgrass, creeping bent, fiorin, spreading bent or carpet bentgrass) is a perennial grass species in the family Poaceae. It is widely used as turf for golf courses. Description ''Agrostis stolonifera'' is sto ...

(''Agrostis stolonifera''). It has appeared on King George Island in the

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

South Shetland Islands The South Shetland Islands are a group of List of Antarctic and subantarctic islands, Antarctic islands located in the Drake Passage with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the n ...

as an

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

,Antarctic ecology: Polar invaders

The Economist ''The Economist'' is a British newspaper published weekly in printed magazine format and daily on Electronic publishing, digital platforms. It publishes stories on topics that include economics, business, geopolitics, technology and culture. M ...

, Mar 6th 2012 as well as on

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

subantarctic The sub-Antarctic zone is a physiographic region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46th parallel south, 46° and 60th parallel south, 60° south of t ...

Heard and

Macquarie Island Macquarie Island is a subantarctic island in the south-western Pacific Ocean, about halfway between New Zealand and Antarctica. It has been governed as a part of Tasmania, Australia, since 1880. It became a Protected areas of Tasmania, Tasmania ...

s. 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

External links

European ''Poa'' Database
* The Observers Book of Grasses, Sedges and Rushes. Frances Rose. pages 38–39
Kew gardens grass database
*Weeds friend or foe? Sally Roth. pages 86–87

{{Authority control annua Flora of Europe Flora of Africa Flora of temperate Asia Flora of tropical Asia Garden plants of Europe Lawn grasses Plants described in 1753 Taxa named by Carl Linnaeus Invasive plant species of subantarctic islands Grasses of Lebanon