biology

Poa pratensis

Poa pratensis is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Poa pratensis rather than just read about it. In short: 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 Tunisia. There is disagreement about its native status in North America, with some sources considering it native and others stating the Spanish Empire brought the seeds of Kentucky b…

Key takeaways

Poa pratensis belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Poa pratensis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Poa pratensis from memory before moving on to harder problems.

Reference excerpt

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 Tunisia. There is disagreement about its native status in North America, with some sources considering it native and others stating the Spanish Empire brought the seeds of Kentucky bluegrass to the New World in mixtures with other grasses. It is a very popular lawn grass in North America with the species being spread over all of the cool, humid parts of the United States. In its native range, Poa pratensis forms a valuable pasture plant, characteristic of well-drained, fertile soil. It is also used for making lawns in parks and gardens and has established itself as a common invasive weed across cool moist temperate climates like the Pacific Northwest and the Northeastern United States. When found on native grasslands in Canada, for example, it is considered an unwelcome exotic plant, and is indicative of a disturbed and degraded landscape.

Taxonomy Poa pratensis was one of the many species described by Carl Linnaeus in his landmark work Species Plantarum in 1753. Poa is Greek for fodder and pratensis is derived from pratum, Latin for meadow. The name Kentucky bluegrass derives from its flower heads, which are blue when the plant is allowed to grow to its natural height of 60 to 90 cm (2 to 3 feet). Poa pratensis is the type species of the grass family Poaceae. Five subspecies are accepted.

Poa pratensis subsp. dolichophylla (Hack.) Portal – Corsica Poa pratensis subsp. jordanii Portal – eastern France Poa pratensis subsp. oligantha Charit. – western Siberia Poa pratensis subsp. pratensis – temperate North America and Eurasia; Yemen, the Philippines, Java, and New Guinea Poa pratensis subsp. turfosa (Litv.) Vorosch. – Baltic States and northern and Central European Russia

Description Poa pratensis is a herbaceous perennial plant 30–70 centimetres (12–28 in) tall. The leaves have boat-shaped tips, narrowly linear, up to 20 centimetres (8 in) long and 3–5 millimetres (0.12–0.20 in) broad, smooth or slightly roughened, with a rounded to truncate ligule 1–2 millimetres (0.039–0.079 in) long. The conical panicle is 5–20 centimetres (2–8 in) long, with 3 to 5 branches in the basal whorls; the oval spikelets are 3–6 millimetres (0.12–0.24 in) long with 2 to 5 florets, and are purplish-green or grey. They are in flower from May to July, compared to annual meadowgrass (Poa annua) which is in flower for eight months of the year. Poa pratensis has a fairly prominent mid-vein (center of the blade). The ligule is extremely short and square-ended, making a contrast with annual meadowgrass (Poa annua) and rough meadowgrass (Poa trivialis) in which it is silvery and pointed. The Kentucky bluegrass is a dark green/blue compared to the apple-green color of Poa annua and Poa trivialis. The rootstock is creeping, with runners (rhizomes). The broad, blunt leaves tend to spread at the base, forming close mats.

Ecology

Poa pratensis is among the food plants of the caterpillars of the meadow brown (Maniola jurtina), gatekeeper (Pyronia tithonus), and pepper-and-salt skipper butterflies; the common sun beetle (Amara aenea) (adults feed on the developing seeds), the leafhopper Eupelix cuspidata, the grassbug Myrmus miriformis (feeds on young blades and developing seeds), and the club-horned grasshopper (Aeropedellus clavatus) (feeds on the blades, seeds, and glumes). Poa pratensis is host to a number of fungi, including Claviceps purpurea, which causes ergotism when consumed, Drechslera poae, Epichloë typhina, Phaeoseptoria poae, Puccinia brachypodii var. poae-nemoralis, Stagonospora montagnei, Stagonospora nodorum and Wojnowicia hirta.

Cultivation and production The Central Kentucky Blue Grass Seed Company Building is on the National Register of Historic Places. Since the 1950s and early 1960s, 90% of Kentucky bluegrass seed in the United States has been produced on specialist farms in Idaho, Oregon and Washington. During the 1990s, botanists began experimenting with hybrids of Poa pratensis and Texas bluegrass (P. arachnifera), with the goal of creating a drought and heat-resistant lawn grass. In warm climates, such hybrids may remain green year-round. Bella Bluegrass is a brand-named dwarf variant of Poa pratentis developed by the University of Nebraska–Lincoln. It has relatively deep roots and propagates relatively rapidly horizontally from its root system but grows to only 2–5 inches (5–13 cm) in above-ground height, basically eliminating the need for mowing lawns that use it. It cannot be reproduced by seed and thus depends on sod plugs or sprigging for its production.

NFL playing surfaces Source:

Huntington Bank Field in Cleveland, Ohio Empower Field at Mile High in Denver, Colorado New Highmark Stadium in Orchard Park, New York Acrisure Stadium in Pittsburgh, Pennsylvania

MLB playing surfaces Source:

Yankee Stadium in Bronx, New York Oriole Park at Camden Yards in Baltimore, Maryland Progressive Field in Cleveland, Ohio Angel Stadium in Anaheim, California Busch Stadium in St. Louis, Missouri Citizens Bank Park in Philadelphia, Pennsylvania American Family Field in Milwaukee, Wisconsin Nationals Park in Washington, D.C. Citi Field in Queens, New York Comerica Park in Detroit, Michigan Guaranteed Rate Field in Chicago, Illinois Target Field in Minneapolis, Minnesota PNC Park in Pittsburgh, Pennsylvania Fenway Park in Boston, Massachusetts Oakland Coliseum in Oakland, California Coors Field in Denver, Colorado (Kentucky Bluegrass/Perennial Ryegrass Blend) T-Mobile Park in Seattle, Washington (Kentucky Bluegrass/Perennial Ryegrass Blend) Great American Ball Park in Cincinnati, Ohio (Kentucky Bluegrass Blend) Wrigley Field in Chicago, Illinois (Kentucky Bluegrass/Clover Blend) Kauffman Stadium in Kansas City, Missouri (Kentucky Bluegrass/Perennial Ryegrass Blend)

Gallery

References

Further reading Flora Europaea: Poa pratensis European Poa Database Horticultural information on this turfgrass; growing it in the home garden * The Observers Book of Grasses, Sedges and Rushes. Frances Rose. pages 42–43 PennState Extension Kentucky Bluegrass Facts and Identification Kew gardens grass database

External links Media related to poa pratensis (category) at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with Poa pratensis

Start with the simplest possible case. Write down what Poa pratensis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Poa pratensis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Poa pratensis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Poa pratensis

In research: Poa pratensis appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Poa pratensis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Poa pratensis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Botanical taxa named by Carl Linnaeus, Cosmopolitan species, Grasses of Africa, so understanding it makes those chapters shorter.
In everyday life: Look for Poa pratensis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Poa pratensis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Poa pratensis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Poa pratensis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Poa pratensis in simple terms?

Why does Poa pratensis matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Poa pratensis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Poa pratensis.