Poaceae () or Gramineae () is a large and nearly ubiquitous
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
of
monocotyledon
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 embryonic leaf, or cotyledon. They constitute one of ...
ous
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s commonly known as grasses. It includes the
cereal
A cereal is any Poaceae, grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, Cereal germ, germ, and bran. Cereal Grain, grain crops are grown in greater quantit ...
grasses,
bamboo
Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...
s and the grasses of natural
grassland
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
and species cultivated in
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. L ...
s and
pasture
Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep, or swine ...
. The latter are commonly referred to collectively as grass.
With around 780
genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
and around 12,000 species,
the Poaceae is the fifth-largest
plant family
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of ...
, following the
Asteraceae
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...
,
Orchidaceae
Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant.
Along with the Asteraceae, they are one of the two largest families of flowering ...
,
and
Rubiaceae
The Rubiaceae are a 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 interpetiolar stipules ...
.
The Poaceae are the most economically important plant family, providing
staple food
A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
s from domesticated
cereal
A cereal is any Poaceae, grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, Cereal germ, germ, and bran. Cereal Grain, grain crops are grown in greater quantit ...
crops such as
maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
,
wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that 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 archaeologi ...
,
rice
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
,
barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley pr ...
, and
millet
Millets () are a highly varied group of small-seeded grasses, widely grown around the world as cereal crops or grains for fodder and human food. Most species generally referred to as millets belong to the tribe Paniceae, but some millets al ...
as well as
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 fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legum ...
s 6%. Some members of the Poaceae are used as building materials (
bamboo
Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...
,
thatch
Thatching is the craft of building a roof with dry vegetation such as straw, water reed, sedge (''Cladium mariscus''), rushes, heather, or palm branches, layering the vegetation so as to shed water away from the inner roof. Since the bulk of ...
, and
straw
Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...
); others can provide a source of
biofuel
Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (E ...
, primarily via the conversion of maize to
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
.
Grasses have
stem
Stem or STEM may refer to:
Plant structures
* Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang
* Stipe (botany), a stalk to support some other structure
* Stipe (mycology), the stem of a mushro ...
s that are hollow except 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
*Vertex (geometry), a point where two ...
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
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
s such as
savannah
A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the Canopy (forest), canopy does not close. The open canopy allows sufficient light to rea ...
and
prairie
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
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 harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, excluding
Greenland
Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
and
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
. Grasses are also an important part of the vegetation in many other habitats, including
wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...
s,
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 function. The United Nations' ...
s and
tundra
In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless moun ...
.
Though they are commonly called "grasses", groups such as the
seagrasses
Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the orde ...
,
rushes and
sedges
The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...
fall outside this family. The rushes and sedges are related to the Poaceae, being members of the
order Poales
The Poales are a large order of flowering plants in the monocotyledons, and includes families of plants such as the grasses, bromeliads, and sedges. Sixteen plant families are currently recognized by botanists to be part of Poales.
Descriptio ...
, but the seagrasses are members of order
Alismatales
The Alismatales (alismatids) are an order of flowering plants including about 4,500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats.
Description
The Alismatales compri ...
. 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 embryonic leaf, or cotyledon. They constitute one of ...
group of plants.
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 (b ...
or
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 wide ...
herbs
In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...
,
[ generally with the following characteristics (the image gallery can be used for reference):
The stems 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
*Vertex (geometry), a point where two ...
, where the leaves are attached. Grass leaves
A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
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 of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
phytolith
Phytoliths (from Greek, "plant stone") are rigid, microscopic structures made of silica, found in some plant tissues and persisting after the decay of the plant. These plants take up silica from the soil, whereupon it is deposited within different ...
s, which discourage grazing animals; some, such as sword grass, 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 and leafstalk of many grasses (Poaceae) and sedges. A ligule is also a strap-shaped extension of the corolla, such as that of a ...
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, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s of Poaceae are characteristically arranged in 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, each having one or more florets.[ The spikelets are further grouped into panicles or spikes. The part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two (or sometimes fewer) ]bracts
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...
at the base, called glumes
In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma and ...
, 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
Science and mathematics
* Lemma (botany), a ...
—and one internal—the palea. The flowers are usually hermaphroditic
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes.
Many taxonomic groups of animals (mostly invertebrates) do not have separ ...
—maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
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 grasses, sedges, and rushes. Other common anemophilous plan ...
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 (sepals) and the corolla (petals) or tepals when ...
is reduced to two scales, called ''lodicule
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'',[ that expand and contract to spread the lemma and palea; these are generally interpreted to be modified sepals. The ]fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
of grasses is a caryopsis
In botany, a caryopsis (plural caryopses) is a type of simple fruit—one that is monocarpellate (formed from a single carpel) and indehiscent (not opening at maturity) and resembles an achene, except that in a caryopsis the pericarp is fused ...
, in which the seed coat is fused to the fruit wall.[
A ]tiller
A tiller or till is a lever used to steer a vehicle. The mechanism is primarily used in watercraft, where it is attached to an outboard motor, rudder post or stock to provide leverage in the form of torque for the helmsman to turn the rudder. ...
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 grazed or mown regularly without severe damage to the plant.
Three general classifications of growth habit present in grasses: bunch-type (also called caespitose), stolon
In biology, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external s ...
iferous, and rhizomatous
In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
.
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 character in ''Black Cat'' comic series
See also
* Frankfurter Kranz, cake
* Krantz, a surname
* Cranz (disambiguation)
* Crantz (1722–1799), European botanist & physician Hei ...
, which allows for increased water use efficiency
Water-use efficiency (WUE) refers to the ratio of water used in plant metabolism to water lost by the plant through transpiration. Two types of water-use efficiency are referred to most frequently:
*photosynthetic water-use efficiency (also call ...
, 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 that 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 archaeologi ...
, 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 ...
''), and oat
The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human con ...
* Perennial cool-season – orchardgrass (cocksfoot, ''Dactylis glomerata
''Dactylis Glomerata'' is the sixth studio album by Swedish doom metal band Candlemass, released in 1998. This was their first album released since their split in 1994.
The album was originally destined to be the second release by Candlemass ...
''), fescue (''Festuca
''Festuca'' (fescue) is a genus of flowering plants belonging to the grass family Poaceae (subfamily Pooideae). They are evergreen or herbaceous perennial tufted grasses with a height range of and a cosmopolitan distribution, occurring on every ...
'' spp.), Kentucky bluegrass
''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 and Morocco. Altho ...
and perennial ryegrass (''Lolium perenne
''Lolium perenne'', common name perennial ryegrass, English ryegrass, winter ryegrass, or ray grass, is a grass from the family Poaceae. It is native to Europe, Asia and northern Africa, but is widely cultivated and naturalised around the world.
...
'')
* Annual warm-season – maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
, sudangrass, and pearl millet
Pearl millet (''Cenchrus americanus'', commonly known as the synonym ''Pennisetum glaucum''; also known as 'Bajra' in Hindi, 'Sajje' in Kannada, 'Kambu' in Tamil, 'Bajeer' in Kumaoni and 'Maiwa' in Hausa, 'Mexoeira' in Mozambique) is the most w ...
* Perennial warm-season – big bluestem
''Andropogon gerardi'', commonly known as big bluestem, is a species of tall grass native to much of the Great Plains and grassland regions of central and eastern North America. It is also known as tall bluestem, bluejoint, and turkeyfoot.
Taxon ...
, Indiangrass
''Sorghastrum nutans'', commonly known as either Indiangrass or yellow Indiangrass, is a North American prairie grass found in the central and eastern United States and Canada, especially in the Great Plains and tallgrass prairies.
Descriptio ...
, Bermudagrass
''Cynodon dactylon'', commonly known as Bermuda grass, is a grass found worldwide. It is native to Europe, Africa, Australia and much of Asia. It has been introduced to the Americas. Although it is not native to Bermuda, it is an abundant invasi ...
and switchgrass
''Panicum virgatum'', commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico. Switchgrass is one of the ...
.
Although the C4 species are all in the PACMAD clade
The PACMAD clade (previously PACCMAD, PACCAD, or PACC) is one of two major lineages (or clades) of the true grasses (Poaceae), regrouping six subfamilies and about 5700 species, more than half of all true grasses. Its sister group is the BOP c ...
(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
''Aristida'' is a very nearly cosmopolitan genus of plants in the grass family. ''Aristida'' is distinguished by having three awns (bristles) on each lemma of each floret. The genus includes about 300 species found worldwide, often in arid war ...
'' 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
The Andropogoneae, sometimes called the sorghum tribe, are a large tribe of grasses (family Poaceae) with roughly 1,200 species in 90 genera, mainly distributed in tropical and subtropical areas. They include such important crops as maize (corn), ...
, which includes maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
, sorghum
''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many othe ...
, sugar cane
Sugarcane or sugar cane is a species of (often hybrid) tall, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar production. The plants are 2–6 m (6–20 ft) tall with stout, jointed, fibrous stalks t ...
, "Job's tears
Job's tears (''Coix lacryma-jobi)'', also known as Adlay or Adlay millet, is a tall grain-bearing perennial tropical plant of the family Poaceae (grass family). It is native to Southeast Asia and introduced to Northern China and India in remote ...
", and bluestem grass
Bluestem can refer to various grasses:
* Little bluestem (''Schizachyrium scoparium'')
* Big bluestem (''Andropogon gerardii'') and other species of the genus '' Andropogon''
* Species in the genus ''Dichanthium''
* Cane bluestem and Caucasian bl ...
es, is C4. Around 46 percent of grass species are C4 plants.
Taxonomy
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'' Augu ...
in 1895, based on the tribe Poeae described in 1814 by Robert Brown, and the type genus '' Poa'' described in 1753 by Carl Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
. The term is derived from the Ancient Greek Wiktionary:Poa, πόα (póa, "fodder").
Evolutionary history
Grasses include some of the most versatile plant life-forms. They became widespread toward the end of the Cretaceous period, and fossilized dinosaur dung (coprolites) have been found containing phytolith
Phytoliths (from Greek, "plant stone") are rigid, microscopic structures made of silica, found in some plant tissues and persisting after the decay of the plant. These plants take up silica from the soil, whereupon it is deposited within different ...
s of a variety that include grasses that are related to modern rice
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
and bamboo
Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...
. Grasses have adapted to conditions in lush rain forests, dry deserts, cold mountains and even Intertidal ecology, intertidal habitats, and are currently the most widespread plant type; grass is a valuable source of food and energy for all sorts of wildlife.
A cladogram shows subfamilies and approximate species numbers in brackets:[ ]
Before 2005, fossil findings indicated that grasses evolved around 55 million years ago. Finds of grass-like phytolith
Phytoliths (from Greek, "plant stone") are rigid, microscopic structures made of silica, found in some plant tissues and persisting after the decay of the plant. These plants take up silica from the soil, whereupon it is deposited within different ...
s in Cretaceous dinosaur coprolites from the latest Cretaceous (Maastrichtian) aged Lameta Formation of India have pushed this date back to 66 million years ago. In 2011, fossils from the same deposit were found to belong to the modern rice tribe Oryzeae, suggesting substantial diversification of major lineages by this time.
Wu, You & Li (2018) described grass microfossils extracted from the teeth of the Hadrosauroidea, hadrosauroid dinosaur ''Equijubus normani'' from northern China, dating to the Albian stage of the Early Cretaceous approximately 113–100 million years ago, which were found to belong to primitive lineages within Poaceae, similar in position to the Anomochlooideae. These are currently the oldest known grass fossils.
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 the spread of grasses in the Neogene, Late Cenozoic would have changed patterns of hillslope evolution favouring slopes that are convex upslope and concave downslope and lacking a escarpment, free face 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 downhill creep, soil creep.
Subdivisions
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 that 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 archaeologi ...
, barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley pr ...
, oat
The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human con ...
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 flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...
* Ehrhartoideae, including rice
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
and wild rice
* Aristideae, Aristidoideae, including ''Aristida
''Aristida'' is a very nearly cosmopolitan genus of plants in the grass family. ''Aristida'' is distinguished by having three awns (bristles) on each lemma of each floret. The genus includes about 300 species found worldwide, often in arid war ...
''
* 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 and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
, sorghum
''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many othe ...
, sugarcane, most millet
Millets () are a highly varied group of small-seeded grasses, widely grown around the world as cereal crops or grains for fodder and human food. Most species generally referred to as millets belong to the tribe Paniceae, but some millets al ...
s, fonio, "Job's tears
Job's tears (''Coix lacryma-jobi)'', also known as Adlay or Adlay millet, is a tall grain-bearing perennial tropical plant of the family Poaceae (grass family). It is native to Southeast Asia and introduced to Northern China and India in remote ...
", and bluestem grass
Bluestem can refer to various grasses:
* Little bluestem (''Schizachyrium scoparium'')
* Big bluestem (''Andropogon gerardii'') and other species of the genus '' Andropogon''
* Species in the genus ''Dichanthium''
* Cane bluestem and Caucasian bl ...
es
* Micrairoideae
* Danthonieae, Danthonioideae, including Cortaderia, pampas grass
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 harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. Grasses are found on every continent, including Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
. The Antarctic hair grass, ''Deschampsia antarctica'' is one of only two plant species native to the western Antarctic Peninsula.
Ecology
Grasses are the Dominance (ecology), dominant vegetation in many habitats, including grassland
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
, 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
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
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.
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 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. L ...
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 that 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 archaeologi ...
, rice, maize (corn) and barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley pr ...
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 Poaceae, grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, Cereal germ, germ, and bran. Cereal Grain, grain crops are grown in greater quantit ...
s'' or ''grain
A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legum ...
s'' (although the latter term, when used agriculturally, refers to both cereals and similar seeds of other plant species, such as buckwheat 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 South 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
Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep, or swine ...
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 byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...
, or in silos as silage. Straw (and sometimes hay) may also be used as bedding for animals.
An example of a sod-forming perennial grass used in agriculture is ''Thinopyrum intermedium''.
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 a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (E ...
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
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
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 Ligule, 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
The PACMAD clade (previously PACCMAD, PACCAD, or PACC) is one of two major lineages (or clades) of the true grasses (Poaceae), regrouping six subfamilies and about 5700 species, more than half of all true grasses. Its sister group is the BOP c ...
* Thinopyrum intermedium
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 Albian first appearances