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Poaceae () or Gramineae () is a large and nearly ubiquitous
family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain the well-being of its members and of society. Ideally, families would off ...
of
monocotyledon Monocotyledons (), commonly referred to as monocots, ( ' Chase & Reveal) are and grass-like s (angiosperms), the s of which typically contain only one nic leaf, or . They constitute one of the major groups into which the flowering plants have tr ...
ous
flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

flowering plant
s known as grasses. It includes the
cereal A cereal is any grass cultivated (grown) for the edible components of its grain A grain is a small, hard, dry seed, with or without an attached husk, hull or fruit layer, harvested for human or animal consumption. A grain crop is a grain-pro ...

cereal
grasses,
bamboo Bamboos are a diverse group of evergreen perennial plant, perennial flowering plants in the subfamily (biology), subfamily Bambusoideae of the grass family ''Poaceae''. The origin of the word "bamboo" is uncertain, but it probably comes from t ...

bamboo
s and the grasses of natural
grassland Grasslands are areas where the vegetation Vegetation is an assemblage of plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things t ...

grassland
and species cultivated in
lawn A lawn is an area of soil-covered land planted with Poaceae, 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 pur ...

lawn
s and pasture. The latter are commonly referred to collectively as grass. With around 780
genera Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying gr ...
and around 12,000 species, the Poaceae is the fifth-largest plant family, following the
Asteraceae The family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain the well-being of its members and of society. Ideally, fam ...

Asteraceae
,
Orchidaceae Orchidaceae ( ), common name, commonly called the orchid family, is a diverse and widespread family (biology), family of flowering plants, with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two lar ...

Orchidaceae
,
Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

Fabaceae
and
Rubiaceae The Rubiaceae are a family (biology), family of flowering plants, commonly known as the coffee, madder, or bedstraw family. It consists of terrestrial trees, shrubs, lianas, or herbs that are recognizable by simple, opposite leaves with Petiole ...
. The Poaceae are the most economically important plant family, providing
staple food 215px, Unprocessed seeds of spelt, a historically important staple food A staple food, food staple, or simply a staple, is a food Food is any substance consumed to provide Nutrient, nutritional support for an organism. Food is usually of pla ...

staple food
s from domesticated
cereal A cereal is any grass cultivated (grown) for the edible components of its grain A grain is a small, hard, dry seed, with or without an attached husk, hull or fruit layer, harvested for human or animal consumption. A grain crop is a grain-pro ...

cereal
crops such as
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
,
wheat Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus ''Triticum''; the most widely grown is common wheat (''T. aestivum''). The archaeological r ...

wheat
,
rice Rice is the seed of the Poaceae, grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera ''Zizania (genus), Zizania'' and ''Porteresia'', bo ...

rice
,
barley Barley (''Hordeum vulgare''), a member of the grass family Poaceae () or Gramineae () is a large and nearly ubiquitous family In human society, family (from la, familia) is a group of people related either by consanguinity (by recogn ...

barley
, and
millet Millets () are a group of highly variable small-seeded grasses, widely grown around the world as cereal crops or grains for fodder and human food. Millets are important crops in the semiarid tropics of Asia and Africa (especially in Indi ...

millet
as well as
feed
feed
for meat-producing animals. They provide, through direct human consumption, just over one-half (51%) of all dietary energy; rice provides 20%, wheat supplies 20%, maize (corn) 5.5%, and other
grain A grain is a small, hard, dry seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, ...

grain
s 6%. Some members of the Poaceae are used as building materials (
bamboo Bamboos are a diverse group of evergreen perennial plant, perennial flowering plants in the subfamily (biology), subfamily Bambusoideae of the grass family ''Poaceae''. The origin of the word "bamboo" is uncertain, but it probably comes from t ...

bamboo
,
thatch Thatching is the craft of building a roof with dry vegetation such as straw Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain A grain is a small, hard, dry seed, with or without an attac ...

thatch
, and
straw Straw is an agricultural consisting of the dry s of plants after the and have been removed. It makes up about half of the yield of cereal crops such as , s, , and . It has a number of different uses, including , and , and . Straw i ...

straw
); others can provide a source of
biofuel Biofuel is fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy Thermal radiation in visible light can be seen on this hot metalwork. Thermal energy refers to several di ...

biofuel
, primarily via the conversion of maize to
ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an . It is a simple with the C2H6O. Its formula can be also written as −− or (an linked to a group), and is often as EtOH. Ethanol is a , , ...

ethanol
. Grasses have
stem Stem or STEM may refer to: Biology * Plant stem, the aboveground structures that have vascular tissue and that support leaves and flowers ** Stipe (botany), a stalk that supports some other structure ** Stipe (mycology), the stem supporting the c ...

stem
s that are hollow except at the nodes and narrow alternate leaves borne in two ranks. The lower part of each leaf encloses the stem, forming a leaf-sheath. The leaf grows from the base of the blade, an adaptation allowing it to cope with frequent grazing.
Grassland Grasslands are areas where the vegetation Vegetation is an assemblage of plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things t ...

Grassland
s such as
savannah A savanna or savannah is a mixed woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ' woods), a low-density forming open s with plenty of sunlight and li ...

savannah
and
prairie Wheatfield intersection in the Southern Saskatchewan prairies, Canada. Prairies are ecosystem An ecosystem is a community (ecology), community of living organisms in conjunction with the nonliving components of their environment, interact ...
where grasses are dominant are estimated to constitute 40.5% of the land area of the
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wit ...

Earth
, excluding
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an * * * within the and the , located between the and oceans, east of the . Though a part of the continent of , Greenland has been politically and culturally associated with (spec ...

Greenland
and
Antarctica Antarctica ( or ) is 's southernmost . It contains the geographic and is situated in the region of the , almost entirely south of the , and is surrounded by the . At , it is the fifth-largest continent and nearly twice the size of . At 0.00 ...

Antarctica
. Grasses are also an important part of the vegetation in many other habitats, including
wetland A wetland is a distinct ecosystem that is flooded by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in the soils. ...

wetland
s,
forest A forest is an area of land dominated by s. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ( ...

forest
s and
tundra In physical geography Physical geography (also known as physiography) is one of the two fields of geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of the ...

tundra
. Though they are commonly called "grasses", groups such as the
seagrasses Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...
, rushes and
sedges The Cyperaceae are a family of graminoid In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in t ...
fall outside this family. The rushes and sedges are related to the Poaceae, being members of the
order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or waste, and the habit of achieving a ...
Poales The Poales are a large order (biology), order of flowering plants in the monocotyledons, and includes families of plants such as the Poaceae, grasses, bromeliads, and Cyperaceae, sedges. Sixteen plant families are currently recognized by botanis ...
, but the seagrasses are members of order
Alismatales The Alismatales (alismatids) are an order of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Family (biolog ...
. However, all of them belong to the
monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. The ...
group of plants.


Etymology

The name Poaceae was given by
John Hendley Barnhart John Hendley Barnhart (October 4, 1871 – November 11, 1949) was an American botanist and author, specializing in biographies of botanists.Gleaston, H. A. John Hendley Barnhart—An appreciation. '' Journal of the New York Botanical Garden'' August ...
in 1895, based on the tribe Poeae described in 1814 by Robert Brown, and the type genus ''
Poa ''Poa'' is a of about 500 of es, native to the temperate regions of both hemispheres. Common names include meadow-grass (mainly in Europe and Asia), bluegrass (mainly in North America), tussock (some species), and speargrass. ''Poa'' () is ...

Poa
'' described in 1753 by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his as Carl von Linné, p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised , the modern system of naming organisms. He is known as the ...

Carl Linnaeus
. The term is derived from the Ancient Greek πόα (póa, "fodder").


Evolutionary history

Grasses include some of the most versatile
plant life-formPlant life-form schemes constitute a way of classifying plants alternatively to the ordinary species-genus-family scientific classification In biology Biology is the natural science that studies life and living organisms, including thei ...
s. They became widespread toward the end of the
Cretaceous The Cretaceous ( ) is a that lasted from about 145 to 66 (Mya). It is the third and final period of the , as well as the longest. At around 79 million years, it is the longest geological period of the entire . The name is derived from the Latin ...

Cretaceous
period, and fossilized
dinosaur Dinosaurs are a diverse group of reptile Reptiles, as most commonly defined, are the animals in the Class (biology), class Reptilia , a paraphyletic grouping comprising all amniotes except synapsids (mammals and their extinct relatives) a ...

dinosaur
dung (
coprolite A coprolite (also known as a coprolith) is fossilized A fossil (from Classical Latin Classical Latin is the form of Latin language Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the ...

coprolite
s) have been found containing
phytolith Phytoliths (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approxim ...
s of a variety that include grasses that are related to modern
rice Rice is the seed of the Poaceae, grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera ''Zizania (genus), Zizania'' and ''Porteresia'', bo ...

rice
and
bamboo Bamboos are a diverse group of evergreen perennial plant, perennial flowering plants in the subfamily (biology), subfamily Bambusoideae of the grass family ''Poaceae''. The origin of the word "bamboo" is uncertain, but it probably comes from t ...

bamboo
. Grasses have adapted to conditions in lush
rain forest Rainforests are forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing and ecological func ...

rain forest
s, dry
desert upright=1.5, alt=see caption, Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab Emirates">Rub'_al_Khali.html" ;"title="Sand dunes in the Rub' al Khali">Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab ...

desert
s, cold mountains and even intertidal habitats, and are currently the most widespread plant type; grass is a valuable source of food and energy for all sorts of wildlife and organics. A cladogram shows subfamilies and approximate species numbers in brackets: Before 2005, fossil findings indicated that grasses evolved around 55 million years ago. Findings of grass-like
phytolith Phytoliths (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approxim ...
s in
Cretaceous The Cretaceous ( ) is a that lasted from about 145 to 66 (Mya). It is the third and final period of the , as well as the longest. At around 79 million years, it is the longest geological period of the entire . The name is derived from the Latin ...

Cretaceous
dinosaur
coprolite A coprolite (also known as a coprolith) is fossilized A fossil (from Classical Latin Classical Latin is the form of Latin language Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the ...

coprolite
s from the latest Cretaceous (
Maastrichtian The Maastrichtian () is, in the ICS ICS may refer to: Computing * Image Cytometry Standard, a digital multidimensional image file format used in life sciences microscopy * Industrial control system, computer systems and networks used to contr ...
) aged
Lameta Formation The Lameta Formation, also known as the Infratrappean Beds, is a sedimentary Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at the Earth's surface, followed by cementation ...
of India have pushed this date back to 66 million years ago. In 2011, revised dating of the origins of the rice tribe
Oryzeae Oryzeae is a tribe The term tribe is used in many different contexts to refer to a category of human Humans (''Homo sapiens'') are the most populous and widespread species of primates, characterized by bipedality, opposable thumbs, hairl ...
due to findings from the same deposit suggested a date as early as 107 to 129 Mya. Wu, You & Li (2018) described grass microfossils extracted from a specimen of the
hadrosauroid Hadrosauroidea is a clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic—that is, composed of a common ancestor and all its lineag ...
dinosaur Dinosaurs are a diverse group of reptile Reptiles, as most commonly defined, are the animals in the Class (biology), class Reptilia , a paraphyletic grouping comprising all amniotes except synapsids (mammals and their extinct relatives) a ...

dinosaur
''
Equijubus ''Equijubus'' (; ''Mǎzōng'' meaning "horse mane" after the area Mǎzōng Mountain 马鬃山 in which it was found), is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of thi ...
normani'' from the
Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145& ...
(
Albian The Albian is both an age of the geologic timescale The geologic time scale (GTS) is a system of chronological datingChronological dating, or simply dating, is the process of attributing to an object or event a date in the past, allowing suc ...
) Zhonggou Formation (
China China (), officially the People's Republic of China (PRC; ), is a country in . It is the world's , with a of more than 1.4 billion. China spans five geographical and 14 different countries, the in the world after . Covering an area of ap ...

China
), which were found to belong to primitive lineages within Poaceae, similar in position to the Anomochlooideae. The authors noted that India became separated from
Antarctica Antarctica ( or ) is 's southernmost . It contains the geographic and is situated in the region of the , almost entirely south of the , and is surrounded by the . At , it is the fifth-largest continent and nearly twice the size of . At 0.00 ...

Antarctica
, and therefore also all other continents, approximately at the beginning of late
Aptian The Aptian is an in the or a in the . It is a subdivision of the or and encompasses the time from 125.0 ± 1.0 to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the and precedes the , all part of the Lower/Early ...
, so the presence of grasses in both India and China during the Cretaceous indicates that the ancestor of Indian grasses must have existed before late Aptian. Wu, You & Li considered the
Barremian The Barremian is an age in the geologic timescale The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and ...
origin for grasses to be probable. The relationships among the three subfamilies Bambusoideae, Oryzoideae and Pooideae in the BOP clade have been resolved: Bambusoideae and Pooideae are more closely related to each other than to Oryzoideae. This separation occurred within the relatively short time span of about 4 million years. According to
Lester Charles King Lester Charles King (1907–1989) was an English geologist and geomorphologist known for his theories on scarp retreat. He offered a very different view of the origin of continental landscaping than that of William Morris Davis William Morris Dav ...
the spread of grasses in the would have changed patterns of hillslope evolution favouring slopes that are convex upslope and concave downslope and lacking a were common. King argued that this was the result of more slowly acting surface wash caused by carpets of grass which in turn would have resulted in relatively more soil creep.


Description

Grasses may be
annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year **Yearbook **Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), a ...
or
perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and incl ...
herbs, generally with the following characteristics (the image gallery can be used for reference): The of grasses, called culms, are usually cylindrical (more rarely flattened, but not 3-angled) and are hollow, plugged at the
nodes In general, a node is a localized swelling (a "knot") or a point of intersection (a Vertex (graph theory), vertex). Node may refer to: In mathematics *Vertex (graph theory), a vertex in a mathematical graph *Node (autonomous system), behaviour fo ...
, where the leaves are attached. Grass
leaves A leaf (plural leaves) is the principal lateral appendage of the vascular plant plant stem, stem, usually borne above ground and specialized for photosynthesis. The leaves, stem, flower and fruit together form the shoot system. Leaves are ...

leaves
are nearly always alternate and distichous (in one plane), and have parallel veins. Each leaf is differentiated into a lower sheath hugging the stem and a blade with entire (i.e., smooth) margins. The leaf blades of many grasses are hardened with
silica Silicon dioxide, also known as silica, is an oxide An oxide () is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any su ...

silica
phytolith Phytoliths (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approxim ...
s, which discourage grazing animals; some, such as , are sharp enough to cut human skin. A membranous appendage or fringe of hairs called the
ligule A ligule (from "strap", variant of ''lingula'', from ''lingua'' "tongue") is a thin outgrowth at the junction of leaf A leaf (plural leaves) is the principal lateral appendage of the , usually borne above ground and specialized for . Th ...
lies at the junction between sheath and blade, preventing water or insects from penetrating into the sheath.
Flower A flower, sometimes known as a bloom or blossom Image:Cerisier du Japon Prunus serrulata.jpg, Cherry blossoms in Paris in full bloom. In botany, blossoms are the flowers of stone fruit fruit tree, trees (genus ''Prunus'') and of some other plan ...

Flower
s of Poaceae are characteristically arranged in
spikelet A spikelet, in botany, describes the typical arrangement of the flowers of Poaceae, grasses, Cyperaceae, sedges and some other Monocots. Each spikelet has one or more florets. The spikelets are further grouped into Raceme, panicles or spikes. The ...
s, each having one or more florets. The spikelets are further grouped into . The part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two (or sometimes fewer)
bracts ''). All the "leaves" in this image are bracts. In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in th ...

bracts
at the base, called
glumes Chaff (; ) is the dry, scaly protective of s or similar fine, dry, scaly plant material (such as scaly parts of s or finely chopped ). Chaff is indigestible by humans, but can eat it. In it is used as livestock , or is a waste material ed into ...
, followed by one or more florets. A floret consists of the flower surrounded by two bracts, one external—the
lemma Lemma may refer to: Language and linguistics * Lemma (morphology), the canonical, dictionary or citation form of a word * Lemma (psycholinguistics), a mental abstraction of a word about to be uttered * Headword, under which a set of related dict ...
—and one internal—the palea. The flowers are usually
hermaphroditic In reproductive biology, a hermaphrodite () is an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life ...
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
being an important exception—and mainly
anemophilous Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including Poaceae, grasses, Cyperaceae, sedges, and Juncaceae, rushes. ...
or wind-pollinated, although insects occasionally play a role. The
perianth The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (botany), calyx (sepals) and the corolla (flower), ...
is reduced to two scales, called ''
lodicule A spikelet, in botany, describes the typical arrangement of the flowers of Poaceae, grasses, Cyperaceae, sedges and some other Monocots. Each spikelet has one or more florets. The spikelets are further grouped into Raceme, panicles or spikes. The ...
s'', that expand and contract to spread the lemma and palea; these are generally interpreted to be modified sepals. The
fruit In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the ...

fruit
of grasses is a
caryopsis Wheat spikelet with the three anthers sticking out, right In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who spec ...
, in which the seed coat is fused to the fruit wall. A
tiller A tiller or till is a lever A lever ( or ) is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or '':wikt:fulcrum, fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the loc ...
is a leafy shoot other than the first shoot produced from the seed.


Growth and development

Grass blades grow at the base of the blade and not from elongated stem tips. This low growth point evolved in response to grazing animals and allows grasses to be or regularly without severe damage to the plant. Three general classifications of growth habit present in grasses: bunch-type (also called caespitose),
stolon In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms ...
iferous, and
rhizomatous Lotus rhizome peeled and sliced In botany Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds ...

rhizomatous
. The success of the grasses lies in part in their morphology and growth processes and in part in their physiological diversity. There are both C3 and C4 grasses, referring to the photosynthetic pathway for carbon fixation. The C4 grasses have a photosynthetic pathway, linked to specialized
Kranz leaf anatomy Kranz may refer to: * Kranz (surname) * Kranz Maduke, fictional List_of_Black_Cat_characters#Kranz_Maduke, character in ''Black Cat'' comic series See also

* Frankfurter Kranz, cake * Krantz, a surname * Cranz (disambiguation) * Crantz (1 ...
, which allows for increased
water use efficiency Water-use efficiency (WUE) refers to the ratio In mathematics, a ratio indicates how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eigh ...
, rendering them better adapted to hot, arid environments. The C3 grasses are referred to as "cool-season" grasses, while the C4 plants are considered "warm-season" grasses. * Annual cool-season –
wheat Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus ''Triticum''; the most widely grown is common wheat (''T. aestivum''). The archaeological r ...

wheat
,
rye Rye (''Secale cereale'') is a grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants known as grasses. It includes the cereal grasses, bamboo Bamboos are a diverse group of ev ...

rye
, annual bluegrass (annual meadowgrass, ''
Poa annua ''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 ...

Poa annua
''), and
oat The oat (''Avena sativa''), sometimes called the common oat, is a of grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and ). While oats are suitable for human consumption as and , one of the m ...
* Perennial cool-season – orchardgrass (cocksfoot, ''
Dactylis glomerata:''For information on the plant Cocksfoot, please refer to Dactylis glomerata.'' ''Dactylis Glomerata'' is the sixth studio album by Swedish doom metal Doom metal is an extreme metal, extreme subgenre of heavy metal music that typically uses s ...

Dactylis glomerata
''), fescue (''
Festuca ''Festuca'' (fescue) is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, includi ...

Festuca
'' spp.),
Kentucky bluegrass ''Poa pratensis'', commonly known as Kentucky bluegrass (or blue grass), smooth meadow-grass, or common meadow-grass, is a perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' ...
and perennial ryegrass (''Lolium perenne'') * Annual warm-season –
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
, sudangrass, and pearl millet * Perennial warm-season – big bluestem, Indiangrass, Bermudagrass and switchgrass. Although the C4 species are all in the PACMAD clade (see diagram above), it seems that various forms of C4 have arisen some twenty or more times, in various subfamilies or genera. In the ''Aristida'' genus for example, one species (''A. longifolia'') is C3 but the approximately 300 other species are C4. As another example, the whole tribe of Andropogoneae, which includes
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
, sorghum, sugar cane, "Job's tears", and bluestem grasses, is C4. Around 46 percent of grass species are C4 plants.


Distribution

The grass family is one of the most widely distributed and abundant groups of plants on
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wit ...

Earth
. Grasses are found on every continent, including
Antarctica Antarctica ( or ) is 's southernmost . It contains the geographic and is situated in the region of the , almost entirely south of the , and is surrounded by the . At , it is the fifth-largest continent and nearly twice the size of . At 0.00 ...

Antarctica
with the presence of Deschampsia antarctica, Antarctic hair grass on the Antarctic Peninsula.


Ecology

Grasses are the Dominance (ecology), dominant vegetation in many habitats, including
grassland Grasslands are areas where the vegetation Vegetation is an assemblage of plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things t ...

grassland
, salt-marsh, reedswamp and steppes. They also occur as a smaller part of the vegetation in almost every other terrestrial habitat. Grass-dominated biomes are called grasslands. If only large, contiguous areas of grasslands are counted, these biomes cover 31% of the planet's land. Grasslands include pampas, steppes, and
prairie Wheatfield intersection in the Southern Saskatchewan prairies, Canada. Prairies are ecosystem An ecosystem is a community (ecology), community of living organisms in conjunction with the nonliving components of their environment, interact ...
s. Grasses provide food to many Grazing (behaviour), grazing mammals, as well as to many List of Lepidoptera that feed on grasses, species of Butterfly, butterflies and moths. Many types of animals eat grass as their main source of food, and are called ''graminivores'' – these include cattle, sheep, horses, rabbits and many invertebrates, such as grasshoppers and the caterpillars of many Satyridae, brown butterflies. Grasses are also eaten by Omnivore, omnivorous or even occasionally by primarily Carnivore, carnivorous animals. Grasses dominate certain Biome, biomes, especially Temperate grasslands, savannas, and shrublands, temperate grasslands, because many species are adapted to grazing and fire. Grasses are unusual in that the meristem is near the bottom of the plant; hence, grasses can quickly recover from cropping at the top. The evolution of large grazing animals in the Cenozoic contributed to the spread of grasses. Without large grazers, fire-cleared areas are quickly colonized by grasses, and with enough rain, tree seedlings. Trees eventually outcompete most grasses. Trampling grazers kill seedling trees but not grasses.


Taxonomy

There are about 12,000 grass species in about 771 genera that are classified into 12 subfamilies. See the full list of Poaceae genera. * Anomochlooideae Robert Knud Friedrich Pilger, Pilg. ex Eva Hedwig Ingeborg Potztal, Potztal, a small lineage of broad-leaved grasses that includes two genera (''Anomochloa'', ''Streptochaeta'') * Pharoideae Lynn G. Clark, L.G.Clark & Emmet J. Judziewicz, Judz., a small lineage of grasses of three genera, including ''Pharus'' and ''Leptaspis'' * Puelioideae L.G.Clark, Mikio Kobayashi, M.Kobay., Sarah Mathews, S.Mathews, Russell Edwin Spangler, Spangler & Elizabeth Anne Kellogg, E.A.Kellogg, a small lineage of the African genus ''Puelia'' * Pooideae, including
wheat Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus ''Triticum''; the most widely grown is common wheat (''T. aestivum''). The archaeological r ...

wheat
,
barley Barley (''Hordeum vulgare''), a member of the grass family Poaceae () or Gramineae () is a large and nearly ubiquitous family In human society, family (from la, familia) is a group of people related either by consanguinity (by recogn ...

barley
,
oat The oat (''Avena sativa''), sometimes called the common oat, is a of grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and ). While oats are suitable for human consumption as and , one of the m ...
s, brome-grass (''Bromus''), reed-grasses (''Calamagrostis'') and many lawn and pasture grasses such as Bluegrass (grass), bluegrass (''Poa'') * Bambusoideae, including
bamboo Bamboos are a diverse group of evergreen perennial plant, perennial flowering plants in the subfamily (biology), subfamily Bambusoideae of the grass family ''Poaceae''. The origin of the word "bamboo" is uncertain, but it probably comes from t ...

bamboo
* Ehrhartoideae, including
rice Rice is the seed of the Poaceae, grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera ''Zizania (genus), Zizania'' and ''Porteresia'', bo ...

rice
and wild rice * Aristideae, Aristidoideae, including ''Aristida'' * Arundinoideae, including giant reed and common reed * Chloridoideae, including the lovegrasses (''Eragrostis'', about 350 species, including teff), dropseeds (''Sporobolus'', some 160 species), finger millet (''Eleusine coracana'' (L.) Gaertn.), and the muhly grasses (''Muhlenbergia'', about 175 species) * Panicoideae, including panic grass,
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
, sorghum, sugarcane, most
millet Millets () are a group of highly variable small-seeded grasses, widely grown around the world as cereal crops or grains for fodder and human food. Millets are important crops in the semiarid tropics of Asia and Africa (especially in Indi ...

millet
s, fonio, "Job's tears", and bluestem grasses * Micrairoideae * Danthonieae, Danthonioideae, including Cortaderia, pampas grass


Uses

Grasses are, in human terms, perhaps the most economically important plant family. Their economic importance stems from several areas, including food production, industry, and
lawn A lawn is an area of soil-covered land planted with Poaceae, 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 pur ...

lawn
s. They have been grown as food for domesticated animals for up to 6,000 years and the grains of grasses such as
wheat Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus ''Triticum''; the most widely grown is common wheat (''T. aestivum''). The archaeological r ...

wheat
, rice, maize (corn) and
barley Barley (''Hordeum vulgare''), a member of the grass family Poaceae () or Gramineae () is a large and nearly ubiquitous family In human society, family (from la, familia) is a group of people related either by consanguinity (by recogn ...

barley
have been the most important human food crops. Grasses are also used in the manufacture of thatching, thatch, paper, fuel, clothing, Building insulation, insulation, timber for fence, fencing, furniture, scaffolding and construction materials, floor matting, #Sports turf, sports turf and basket weaving, baskets.


Food production

Of all crops grown, 70% are grasses. Agricultural grasses grown for their edible seeds are called ''
cereal A cereal is any grass cultivated (grown) for the edible components of its grain A grain is a small, hard, dry seed, with or without an attached husk, hull or fruit layer, harvested for human or animal consumption. A grain crop is a grain-pro ...

cereal
s'' or ''grains'' (although the latter term, when used agriculturally, refers to both cereals and legumes). Three cereals—rice, wheat, and maize (corn)—provide more than half of all calories consumed by humans. Cereals constitute the major source of carbohydrates for humans and perhaps the major source of protein; these include rice (in Southern Asia, southern and eastern Asia), maize (in Central America, Central and South America), and wheat and barley (in Europe, northern Asia and the Americas). Sugarcane is the major source of sugar production. Additional food uses of sugarcane include sprouting, sprouted grain, shoots, and rhizomes, and in drink they include sugarcane juice and plant milk, as well as rum, beer, whisky, and Żubrówka, vodka. Bamboo shoots are used in numerous Asian dishes and broths, and are available in supermarkets in various sliced forms, in both fresh, fermented and canned versions. Lemongrass is a grass used as a culinary herb for its citrus-like flavor and scent. Many species of grass are grown as pasture for foraging or as fodder for prescribed livestock feeds, particularly in the case of cattle, horses, and sheep. Such grasses may be cut and stored for later feeding, especially for the winter, in the form of bales of hay or
straw Straw is an agricultural consisting of the dry s of plants after the and have been removed. It makes up about half of the yield of cereal crops such as , s, , and . It has a number of different uses, including , and , and . Straw i ...

straw
, or in silos as silage. Straw (and sometimes hay) may also be used as bedding for animals.


Industry

Grasses are used as raw material for a multitude of purposes, including construction and in the composition of building materials such as cob (material), cob, for insulation, in the manufacture of paper and board such as oriented structural straw board. Grass fiber can be used for making Esparto#Esparto paper, paper,
biofuel Biofuel is fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy Thermal radiation in visible light can be seen on this hot metalwork. Thermal energy refers to several di ...

biofuel
production, nonwoven fabrics, and as replacement for glass fibers used in reinforced plastics. Bamboo scaffolding is able to withstand typhoon-force winds that would break steel scaffolding. Larger bamboos and ''Arundo donax'' have stout culms that can be used in a manner similar to timber, ''Arundo'' is used to make reeds for woodwind instruments, and bamboo is used for innumerable implements. ''Phragmites, ''Phragmites australis'''' (common reed) is important for thatching and wall construction of homes in Africa. Grasses are used in water treatment systems, in wetland conservation and land reclamation, and used to lessen the erosional impact of urban storm water runoff.


Lawn and ornamental use

Grasses are the primary plant used in lawns, which themselves derive from grazed
grassland Grasslands are areas where the vegetation Vegetation is an assemblage of plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things t ...

grassland
s in Europe. They also provide an important means of erosion control (e.g., along roadsides), especially on sloping land. Grass lawns are an important covering of playing surfaces in many sports, including football (soccer), American football, tennis, golf, cricket, softball and baseball. Ornamental grasses, such as perennial bunch grasses, are used in many styles of garden design for their foliage, inflorescences, seed heads. They are often used in natural landscaping, xeriscaping and slope and beach stabilization in contemporary landscaping, wildlife gardening, and native plant gardening. They are used as screens and hedges.


Sports turf

Grass playing fields, courses and pitches are the traditional playing surfaces for many sports, including American football, association football, baseball, cricket, golf, and Rugby football, rugby. Grass surfaces are also sometimes used for horse racing and tennis. Type of maintenance and species of grass used may be important factors for some sports, less critical for others. In some sports facilities, including indoor domes and other places where maintenance of a grass field would be difficult, grass may be replaced with artificial turf, a synthetic grass-like substitute.


Cricket

In cricket, the pitch is the strip of carefully mowed and rolled grass where the bowler bowls. In the days leading up to the match it is repeatedly mowed and rolled to produce a very hard, flat surface for the ball to bounce off.


Golf

Grass on golf courses is kept in three distinct conditions: that of the ''rough'', the ''fairway'', and the ''putting green''. Grass on the fairway is mown short and even, allowing the player to strike the ball cleanly. Playing from the rough is a disadvantage because the long grass may affect the flight of the ball. Grass on the putting green is the shortest and most even, ideally allowing the ball to roll smoothly over the surface. An entire industry revolves around the development and marketing of turf grass varieties.


Tennis

In tennis, grass is grown on very hard-packed soil, and the bounce of a tennis ball may vary depending on the grass's health, how recently it has been mowed, and the wear and tear of recent play. The surface is softer than hard courts and Clay court, clay (other tennis surfaces), so the ball bounces lower, and players must reach the ball faster resulting in a different style of play which may suit some players more than others. Among the world's most prestigious court for grass tennis is Centre Court at Wimbledon, London which hosts the final of the annual Wimbledon Championships in England, one of the four Grand Slam (tennis), Grand Slam tournaments.


Economically important grasses

A number of grasses are invasive species that damage natural ecosystems, including forms of ''Phragmites australis'' which are native to Eurasia but has spread around the world.


Role in society

Grasses have long had significance in human society. They have been cultivated as feed for people and domesticated animals for thousands of years. The primary ingredient of beer is usually barley or wheat, both of which have been used for this purpose for over 4,000 years. In some places, particularly in suburban areas, the maintenance of a grass lawn is a sign of a homeowner's responsibility to the overall appearance of their neighborhood. One work credits lawn maintenance to: In communities with drought problems, watering of lawns may be outdoor water-use restriction, restricted to certain times of day or days of the week. Many US municipalities and homeowners' associations have rules which require lawns to be maintained to certain specifications, sanctioning those who allow the grass to grow too long. The smell of the freshly cut grass is produced mainly by cis-3-Hexenal. Some common aphorisms involve grass. For example: * "The grass is always greener on the other side" suggests an alternate state of affairs will always seem preferable to one's own. * "Don't let the grass grow under your feet" tells someone to get moving. * "A snake in the grass" means dangers that are hidden. * "When elephants fight, it is the grass which suffers" tells of bystanders caught in the crossfire. A folk myth about grass is that it refuses to grow where any violent death has occurred.Olmert, Michael (1996). ''Milton's Teeth and Ovid's Umbrella: Curiouser & Curiouser Adventures in History'', p. 208. Simon & Schuster, New York. .


Image gallery

File:Ruwbeemdgras Poa trivialis ligula.jpg, Leaves of ''Poa trivialis'' showing the ligules File:Bamboo DSCN2465.jpg, Bamboo stem and leaves, nodes are evident File:Chasmanthium latifolium-spikelet.jpg, A ''Chasmanthium latifolium'' spikelet File:En Spica spiculae.png, Wheat spike and spikelet File:En Aperta.png, Spikelet opened to show caryopsis File:Harestail grass.jpg, Harestail grass File:Grass.jpg, Grass File:Saccharum-officinarum2.JPG, Sugarcane (''Saccharum officinarum'') File:Bromus hordeaceus unten.jpeg, Roots of ''Bromus hordeaceus'' File:Ohra.jpg, Barley mature spikes (''Hordeum vulgare'') File:Koeh-283.jpg, Illustration depicting both staminate and pistillate flowers of maize (''Zea mays'') File:Flowering Grass.JPG, A grass flower head (meadow foxtail) showing the plain-coloured flowers with large anthers. File:Grass Anthers.JPG, Anthers detached from a meadow foxtail flower File:Setaria verticillata W IMG 1084.jpg, ''Setaria verticillata'', bristly foxtail File:Setaria verticillata W IMG 1083.jpg, ''Setaria verticillata'', bristly foxtail File:Oryza sativa in Kadavoor.jpg, ''Oryza sativa'', Kerala, India


See also

* Agrostology * Forb *GrassBase * PACMAD clade


References


External links

*
Need a Definition of Grass?

Vegetative Key to Grasses

Poaceae
a
''The Plant List''


a
''The Families of Flowering Plants (DELTA)''


at th
''Angiosperm Phylogeny Website''

''Poaceae Classification''
from the onlin
''Catalogue of New World Grasses''

Poaceae
at the onlin
''Guide to the Flora of Mongolia''

Poaceae
at the onlin
''Flora of Taiwan''

Poaceae
at the onlin
''Flora of Pakistan''

Poaceae
at the onlin
''Flora of Zimbabwe''

Poaceae
at the onlin
''Flora of Western Australia''
* Grasses of Australia (AusGrass2) – http://ausgrass2.myspecies.info/
Gramineae
at the onlin
''Flora of New Zealand''

NZ Grass Key
An Interactive Key to New Zealand Grasses a
''Landcare Research''

The Grass Genera of the World
a
''DELTA intkey''



''GrassWorld''
{{Authority control Poaceae, Poales families Grasses, Grasslands Plant life-forms Plants by habit Extant Early Cretaceous first appearances