''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 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. The length of growing seasons and period in which they take place vary according to geographical ...

in its name,

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widel ...

bio-types do exist. This grass may have originated as a hybrid between ''

Poa supina ''Poa supina'' is a species of flowering plant belonging to the family Poaceae. Its native range is Morocco, Europe to Mongolia and Himalaya The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the In ...

'' and '' Poa infirma''.

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 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 panicle are of ...

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 flowers 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 spikelet that ...

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 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 forward-most part ...

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 and leafstalk of many grasses (Poaceae) and sedges. A ligule is also a strap-shaped extension of the corolla, such as that of a ...

is pointed and silvery. Compared this to Common Meadowgrass '' Poa pratensis'', 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 pastur ...

'', 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: Greece 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 ...

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, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

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 grasses and other durable plants such as clover which are maintained at a short height with a lawnmower (or sometimes grazing animals) and used for aesthetic and recreational purposes. ...

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". Th ...

s, including the

Oakmont Country Club Oakmont Country Club is a country club in the eastern United States, located mostly in Plum with only a very small portion of the property located in Oakmont, suburbs of Pittsburgh in western Pennsylvania. Established in 1903, its golf course ...

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. Description ''Agrostis stolonifera'' is stoloniferous and may form mats or tufts. The p ...

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

Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and othe ...

South Shetland Islands The South Shetland Islands are a group of Antarctic islands with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the nearest point of the South Orkney Islands. By the Antarctic Treaty of 1 ...

as an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...

,Antarctic ecology: Polar invaders

The Economist ''The Economist'' is a British weekly newspaper printed in demitab format and published digitally. It focuses on current affairs, international business, politics, technology, and culture. Based in London, the newspaper is owned by The Eco ...

, Mar 6th 2012 as well as on

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

subantarctic The sub-Antarctic zone is a region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° and 60° south of the Equator. The subantarctic region includes many islands ...

Heard and

Macquarie Island Macquarie Island is an island in the southwestern Pacific Ocean, about halfway between New Zealand and Antarctica. Regionally part of Oceania and politically a part of Tasmania, Australia, since 1900, it became a Tasmanian State Reserve in 197 ...

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, Stubborn 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