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.

Poales
Temporal range: Late Cretaceous - Recent (but see text) 66–0 Ma
Zboże
Common wheat (Triticum aestivum)
Scientific classification
Kingdom: Plantae
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Small[1]
Families

See text

Diversity
About 1,050 genera

Description

The flowers are typically small, enclosed by bracts, and arranged in inflorescences (except in three species of the genus Mayaca, which possess very reduced, one-flowered inflorescences). The flowers of many species are wind pollinated; the seeds usually contain starch.

Taxonomy

The APG III system (2009) accepts the order within a monocot clade called commelinids, and accepts the following 16 families:[1]

The earlier APG system (1998) adopted the same placement of the order, although it used the spelling "commelinoids". It did not include the Bromeliaceae and Mayaceae, but had the additional families Prioniaceae (now included in Thurniaceae), Sparganiaceae (now in Typhaceae), and Hydatellaceae (now transferred out of the monocots; recently discovered to be an 'early-diverging' lineage of flowering plants).

The morphology-based Cronquist system did not include an order named Poales, assigning these families to the orders Bromeliales, Cyperales, Hydatellales, Juncales, Restionales and Typhales.

In early systems, an order including the grass family did not go by the name Poales but by a descriptive botanical name such as Graminales in the Engler system (update of 1964) and in the Hutchinson system (first edition, first volume, 1926), Glumiflorae in the Wettstein system (last revised 1935) or Glumaceae in the Bentham & Hooker system (third volume, 1883).

Evolution and phylogeny

The earliest fossils attributed to the Poales date to the late Cretaceous period about 66 million years ago, though some studies (e.g., Bremer, 2002) suggest the origin of the group may extend to nearly 115 million years ago, likely in South America. The earliest known fossils include pollen and fruits.

The phylogenetic position of Poales within the commelinids was difficult to resolve, but an analysis using complete chloroplast DNA found support for Poales as sister group of Commelinales plus Zingiberales.[2] Major lineages within the Poales have been referred to as bromeliad, cyperid, xyrid, graminid, and restiid clades. A phylogenetic analysis resolved most relationships within the order but found weak support for the monophyly of the cyperid clade.[3] The relationship between Centrolepidaceae and Restoniaceae within the restiid clade remains unclear; the first may actually be embedded in the latter.[3][4]

Commelinales

Zingiberales

Poales
Bromeliad clade

Bromeliaceae

Typhaceae

Cyperid clade

Mayacaceae

Rapateaceae

Thurniaceae

Cyperaceae

Juncaceae

Xyrid clade

Eriocaulaceae

Xyridaceae

Graminid clade

Flagellariaceae

Poaceae

Ecdeiocoleaceae

Joinvilleaceae

Restiid clade

Anarthriaceae

Centrolepidaceae

Restionaceae

Diversity

The four most species-rich families in the order are:

  • Poaceae: 12,070 species
  • Cyperaceae: 5,500 species
  • Bromeliaceae: 3,170 species
  • Eriocaulaceae: 1,150 species
Typha latifolia Finland

Typha latifolia, Typhaceae

Carex demissa detail.jpeg

Carex demissa, Cyperaceae

N Xyrc D9741

Xyris complanata, Xyridaceae

Elegia capensis CHCH 2

Elegia capensis, Restionaceae

Japanese Foxtail millet 02

Foxtail millet, Poaceae

Uses

The Poales are the most economically important order of monocots and possibly the most important order of plants in general. Within the order, by far the most important family economically is the family of grasses (Poaceae, syn. Gramineae), which includes the starch staples barley, maize, millet, rice, and wheat as well as bamboos (mostly used structurally, like wood, but somewhat as vegetables), and a few "seasonings" like sugarcane and lemongrass. Graminoids, especially the grasses, are typically dominant in open (low moisture but not yet arid, or also fire climax) habitats like prairie/steppe and savannah and thus form a large proportion of the forage of grazing livestock. Possibly due to pastoral nostalgia or simply a desire for open areas for play, they dominate most Western yards as lawns, which consume vast sums of money in upkeep (artificial grazing—mowing—for aesthetics and to keep the allergenic flowers suppressed, irrigation, and fertilizer). Many Bromeliaceae are used as ornamental plants (and one, the pineapple, is internationally grown in the tropics for fruit). Many wetland species of sedges, rushes, grasses, and cattails are important habitat plants for waterfowl, are used in weaving chair seats, and (especially cattails) were important pre-agricultural food sources for man. Two sedges, chufa (Cyperus esculentus, also a significant weed) and water chestnut (Eleocharis dulcis) are still at least locally important wetland starchy root crops.

References

  1. ^ a b Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Archived from the original (PDF) on 2017-05-25. Retrieved 2013-07-06.
  2. ^ Barrett, Craig F.; Baker, William J.; Comer, Jason R.; Conran, John G.; Lahmeyer, Sean C.; Leebens-Mack, James H.; Li, Jeff; Lim, Gwynne S.; Mayfield-Jones, Dustin R.; Perez, Leticia; Medina, Jesus; Pires, J. Chris; Santos, Cristian; Wm. Stevenson, Dennis; Zomlefer, Wendy B.; Davis, Jerrold I. (2015). "Plastid genomes reveal support for deep phylogenetic relationships and extensive rate variation among palms and other commelinid monocots". New Phytologist. 209 (2): 855–870. doi:10.1111/nph.13617. ISSN 0028-646X. PMID 26350789.
  3. ^ a b Bouchenak-Khelladi, Yanis; Muasya, A. Muthama; Linder, H. Peter (2014). "A revised evolutionary history of Poales: origins and diversification". Botanical Journal of the Linnean Society. 175 (1): 4–16. doi:10.1111/boj.12160. ISSN 0024-4074. open access
  4. ^ Briggs, Barbara G.; Marchant, Adam D.; Perkins, Andrew J. (2014). "Phylogeny of the restiid clade (Poales) and implications for the classification of Anarthriaceae, Centrolepidaceae and Australian Restionaceae". Taxon. 63 (1): 24–46. doi:10.12705/631.1. ISSN 0040-0262.

External links

Bromeliaceae

The Bromeliaceae (the bromeliads) are a family of monocot flowering plants of 51 genera and around 3475 known species native mainly to the tropical Americas, with a few species found in the American subtropics and one in tropical west Africa, Pitcairnia feliciana.They are among the basal families within the Poales and are the only family within the order that has septal nectaries and inferior ovaries. These inferior ovaries characterize the Bromelioideae, a subfamily of the Bromeliaceae. The family includes both epiphytes, such as Spanish moss (Tillandsia usneoides), and terrestrial species, such as the pineapple (Ananas comosus). Many bromeliads are able to store water in a structure formed by their tightly-overlapping leaf bases. However, the family is diverse enough to include the tank bromeliads, grey-leaved epiphyte Tillandsia species that gather water only from leaf structures called trichomes, and a large number of desert-dwelling succulents.

The largest bromeliad is Puya raimondii, which reaches 3–4 m tall in vegetative growth with a flower spike 9–10 m tall, and the smallest is Spanish moss.

Commelinids

In plant taxonomy, commelinids (originally commelinoids) (plural, not capitalised) is a name used by the APG IV system for a clade within the monocots, which in its turn is a clade within the angiosperms. The commelinids are the only clade that the APG has informally named within the monocots. The remaining monocots are a paraphyletic unit. Also known as the commelinid monocots it forms one of three groupings within the monocots, and the final branch, the other two groups being the alismatid monocots and the lilioid monocots.

Cymbopogon

Cymbopogon, better known as lemongrass, is a genus of Asian, African, Australian, and tropical island plants in the grass family.

Some species (particularly Cymbopogon citratus) are commonly cultivated as culinary and medicinal herbs because of their scent, resembling that of lemons (Citrus limon). Common names include lemon grass, barbed wire grass, silky heads, citronella grass, cha de Dartigalongue, fever grass, tanglad, serai, hierba Luisa, or gavati chahapati, amongst many others.

Cynodon dactylon

Cynodon dactylon, also known as Vilfa stellata, Bermuda grass, Dhoob, dūrvā grass, dubo, dog's tooth grass, Bahama grass, devil's grass, couch grass, Indian doab, arugampul, grama, wiregrass and scutch grass, is a grass that originated in Africa. Although it is not native to Bermuda, it is an abundant invasive species there. It is presumed to have arrived in North America from Bermuda, resulting in its common name. In Bermuda it has been known as crab grass (also a name for Digitaria sanguinalis).

Cyperaceae

The Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble the closely related rushes and the more distantly related grasses. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus Carex with over 2,000 species. These species are widely distributed, with the centers of diversity for the group occurring in tropical Asia and tropical South America. While sedges may be found growing in almost all environments, many are associated with wetlands, or with poor soils. Ecological communities dominated by sedges are known as sedgelands.

Features distinguishing members of the sedge family from grasses or rushes are stems with triangular cross-sections (with occasional exceptions) and leaves that are spirally arranged in three ranks (grasses have alternate leaves forming two ranks).Some well-known sedges include the water chestnut (Eleocharis dulcis) and the papyrus sedge (Cyperus papyrus), from which the Ancient Egyptian writing material was made. This family also includes cotton-grass (Eriophorum), spike-rush (Eleocharis), sawgrass (Cladium), nutsedge or nutgrass (Cyperus rotundus, a common lawn weed), and white star sedge (Rhynchospora colorata).

Eriocaulaceae

The Eriocaulaceae are a family of monocotyledonous flowering plants in the order Poales, commonly known as the pipewort family. The family is large, with about 1207 known species described in seven genera. They are widely distributed, with the centers of diversity for the group occurring in tropical regions, particularly the Americas. Very few species extend to temperate regions, with only 16 species in the United States, mostly in the southern states from California to Florida, only two species in Canada, and only one species (Eriocaulon aquaticum) in Europe. They tend to be associated with wet soils, many growing in shallow water. This is also reported from the southern part of India and the regions of Western Ghats hot spots.

The species are mostly herbaceous perennial plants, though some are annual plants; they resemble plants in the related families Cyperaceae (sedges) and Juncaceae (rushes), and like them, have rather small, wind-pollinated flowers grouped together in capitulum-like inflorescences.

GeneraActinocephalus

Comanthera

Eriocaulon - pipewort

Lachnocaulon - bogbutton

Leiothrix

Mesanthemum

Paepalanthus

Rondonanthus

Syngonanthus

Tonina

Graminid clade

The graminid clade is a clade of plants in the order Poales uniting four families, of which the grasses (Poaceae) are the most species-rich. Its sister group is the restiid clade.

Juncaceae

Juncaceae is a family of flowering plants, commonly known as the rush family. It consists of 8 genera and about 464 known species of slow-growing, rhizomatous, herbaceous monocotyledonous plants that may superficially resemble grasses and sedges. They often grow on infertile soils in a wide range of moisture conditions. The best-known and largest genus is Juncus. Most of the Juncus species grow exclusively in wetland habitats. A few rushes, such as Juncus bufonius are annuals, but most are perennials.

Paepalanthus bromelioides

Paepalanthus bromelioides is a species in the flowering plant family Eriocaulaceae. This family is placed in the Poales, close to the Bromeliaceae, whose morphology this genus shares. Paepalanthus bromelioides is native to Cerrado, the area in which the carnivorous bromeliad Brocchinia reducta is also found. There is some speculation that the occasional insects trapped in the urn of this plant are evidence of its being a carnivorous plant.

Poaceae

Poaceae () or Gramineae is a large and nearly ubiquitous family of monocotyledonous flowering plants known as grasses, commonly referred to collectively as grass. Poaceae includes the cereal grasses, bamboos and the grasses of natural grassland and cultivated lawns and pasture. Grasses have stems 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. With around 780 genera and around 12,000 species, Poaceae are the fifth-largest plant family, following the Asteraceae, Orchidaceae, Fabaceae and Rubiaceae.Grasslands such as savannah and prairie where grasses are dominant are estimated to constitute 40.5% of the land area of the Earth, excluding Greenland and Antarctica. Grasses are also an important part of the vegetation in many other habitats, including wetlands, forests and tundra.

The Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops such as maize, wheat, rice, barley, and millet as well as forage, building materials (bamboo, thatch, straw) and fuel (ethanol).

Though they are commonly called "grasses", seagrasses, rushes, and sedges fall outside this family. The rushes and sedges are related to the Poaceae, being members of the order Poales, but the seagrasses are members of order Alismatales.

Rapateaceae

The Rapateaceae are a family of flowering plants. The botanical name has been recognized by most taxonomists.

The APG II system of 2003 also recognizes this family, and assigns it to the order Poales in the clade commelinids, in the monocots. This represents a slight change from the APG system, 1998, which left the family unplaced as to order, but placed it in the same clade (although it used the spelling "commelinoids"). The family is divided into 16 genera with a total of about 94 known species, found in tropical South America and tropical west Africa.

The Cronquist system of 1981 also recognized this family and placed it in the order Commelinales in the subclass Commelinidae in class Liliopsida in division Magnoliophyta.

Reed (plant)

Reed is a common name for several tall, grass-like plants of wetlands.

Restionaceae

The Restionaceae, also called restiads and restios, are a family of annual or perennial rush-like flowering plants native to the Southern Hemisphere; they vary from a few centimeters to 3 m in height. Following the APG IV (2016): the family now includes the former families Anarthriaceae, Centrolepidaceae and Lyginiaceae, and as such includes 51 genera with 572 known species. Based on evidence from fossil pollens, the Restionaceae likely originated more than 65 million years ago during the Late Cretaceous period, when the southern continents were still part of Gondwana.

Sparganium

Sparganium (bur-reed) is a genus of flowering plants, described as a genus by Linnaeus in 1753. It is widespread in wet areas in temperate regions of both the Northern and Southern Hemispheres. The plants are perennial marsh plants that can grow to 3.5 m (depending on the species), with epicene flowers.It was previously placed alone in the family Sparganiaceae. Sparganium is closely related to the Typhaceae and the APG III system (2009) includes Sparganium in that family. It has been determined from phylogenetic analysis to be the closest living relative of the genus Typha (cat-tail).

Triodia (plant)

Triodia is a large genus of hummock-forming bunchgrass endemic to Australia. They are known by the common name spinifex, although they are not a part of the coastal genus Spinifex. Many of the soft-leaved members of this species were formerly included in the genus Plectrachne.

Type genus

In biological classification, especially zoology, the type genus is the genus which defines a biological family and the root of the family name.

Typha

Typha is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush, or reedmace, in American English as reed, cattail, or punks, in Australia as cumbungi or bulrush, in Canada as bulrush or cattail, and in New Zealand as raupō. Other taxa of plants may be known as bulrush, including some sedges in Scirpus and related genera.

The genus is largely distributed in the Northern Hemisphere, where it is found in a variety of wetland habitats.

The rhizomes are edible. Evidence of preserved starch grains on grinding stones suggests they were already eaten in Europe 30,000 years ago.

Typhaceae

The Typhaceae () are a family of flowering plants, sometimes called the cattail family. The botanical name for the family has been recognized by most taxonomists.

Xyridaceae

The Xyridaceae are a family of flowering plants. The botanical name has been recognized by many taxonomists and is known as the yellow-eyed grass family.

The APG II system, of 2003 (unchanged from the APG system of 1998), also recognizes this family, and assigns it to the order Poales in the clade commelinids, in the monocots. This treatment in APG II represents a slight change from the APG system of 1998, which had recognized the family Abolbodaceae for some of the plants included here; that family was unplaced as to order, but was assigned to this same clade (although APG used the spelling "commelinoids").

The family contains almost 400 species in five genera, but most of the species are found in the genus Xyris (see also Abolboda). The species are mostly tropical and subtropical.

The Cronquist system of 1981 also recognized such a family and placed it in the order Commelinales in the subclass Commelinidae in class Liliopsida in division Magnoliophyta.

The Wettstein system, last updated in 1935, placed the family in order Enantioblastae.

Xyris torta, twisted yellow-eyed grass, is on Minnesota's endangered species list.

Close up view of wheat Orders of Monocotyledons
Alismatid monocots
Lilioid monocots
Commelinids

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