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Poales

(Order)

Overview

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Poales is 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.

The earliest fossils attributed to the Polaes dates to the late Cretaceous period about 65.5 million years ago, though some studies (e.g., Bremer, 2002) suggest the origin of the of the group may extend to nearly 115 million years ago, likely in South America. The earliest known fossils include pollen and fruits. The flowers are typically small, enclosed by bracts, and arranged in an inflorescence (except in the genus Mayaca, with solitary terminal flowers). The flowers of many species are wind pollinated; the seeds usually contain starch.

The APG III system (2009) accepts the order and places it in a clade called commelinids, in the monocots. It uses this circumscription:

The earlier APG system (1998) adopted the same placement, although it used the spelling "commelinoids", and used the following circumscription (i.e., it did not include the plants in families Bromeliaceae and Mayacaceae in the order):

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 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).

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The Poales is 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 barley, maize, millet, rice, and wheat. It is also the largest family in the order, far outnumbering its competitors:

b>Po ales is 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.

The earliest fossils attributed to the Polaes dates to the late Cretaceous period about 65.5 million years ago, though some studies (e.g., Bremer, 2002) suggest the origin of the of the group may extend to nearly 115 million years ago, likely in South America. The earliest known fossils include pollen and fruits. The flowers are typically small, enclosed by bracts, and arranged in an inflorescence (except in the genus Mayaca, with solitary terminal flowers). The flowers of many species are wind pollinated; the seeds usually contain starch.

The APG III system (2009) accepts the order and places it in a clade called commelinids, in the monocots. It uses this circumscription:

The earlier APG system (1998) adopted the same placement, although it used the spelling "commelinoids", and used the following circumscription (i.e., it did not include the plants in families Bromeliaceae and Mayacaceae in the order):

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 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).

[ Back to top ]

The Poales is 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 barley, maize, millet, rice, and wheat. It is also the largest family in the order, far outnumbering its competitors:

References

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External links

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Taxonomy

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The Order Poales is further organized into finer groupings including:

Families

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Anarthriaceae

Anarthriaceae is the botanical name for a family of flowering plants. Such a family has rarely been recognized by taxonomists. [more]

Bromeliaceae

Bromeliaceae (the bromeliads) is a family of monocot flowering plants of around 3,170 species native mainly to the tropical Americas, with a few species found in the American subtropics and one in tropical west Africa, Pitcairnia feliciana. It is one of the basal families within the Poales and is unique because it is 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 epiphytic Tillandsia species that gather water only from leaf structures called trichomes, and a large number of desert-dwelling succulents. [more]

Centrolepidaceae

Centrolepidaceae is a botanical name for a family of flowering plants. Such a family has been recognized by most taxonomists. [more]

Cyperaceae

Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. 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 all kinds of situations, many are associated with wetlands, or with poor soils. Ecological communities dominated by sedges are known as sedgelands. [more]

Ecdeiocoleaceae

Ecdeiocoleaceae is the botanical name for a family of flowering plants. Such a family has rarely been recognized by taxonomists. [more]

Eriocaulaceae

The Eriocaulaceae or pipewort family is a family of monocotyledonous flowering plants in the order Poales. The family is large, with about 1,150-1,200 species described in ten genera. The family is 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 e.g. 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 repoted from Southern part of India and the regions of Western Ghats Hot spots. [more]

Flagellariaceae

Lianas high climbing, robust, glabrous. Rhizome sympodial, diffuse. Stems terete, solid, hard, apically usually equally branched; axillary buds absent. Leaves distichous, circinate; leaf sheath tubular, closed, connected with leaf blade by a short pseudopetiole; leaf blade grasslike, stomata paracytic, apex extended into tendril; tendril simple, involutely coiled, abaxially flattened, hard. Inflorescences terminal, paniculate. Flowers bisexual or rarely unisexual, sessile, actinomorphic, 3-merous, small; perianth segments 6, in 2 whorls, free, whitish, petaloid, membranous, persistent, 3 inner ones largest. Stamens 6, in 2 whorls, exserted; filaments filiform; anthers basifixed, linear-oblong to linear, sagittate, 2-loculed, latrorse, dehiscing by longitudinal slits; pollen grains ulcerate and similar to those of grasses. Ovary superior, obtusely 3-angled, 3-loculed; ovule 1 per locule; placentation axile. Style very short; stigmas 3, linear-clavate. Fruit drupaceous with 1(or 2) seeds. Seeds globose or flattened; endosperm copious, starchy; embryo minute.[1] [more]

Gramineae

[more]

Joinvilleaceae

Joinvilleaceae is a family of flowering plants. The APG II system, of 2003 (unchanged from the APG system, 1998) assigns it to the order Poales in the clade commelinids in the monocots. The family consists of one genus with four currently accepted species, distributed from the Malay Peninsula to the Caroline Islands and high islands in the Pacific Ocean. It is evolutionarily significant as a relictual group that is a close relative of grasses. They closely resemble large grass plants, in both general appearance and microanatomy, but possess fleshy fruits. [more]

Juncaceae

Juncaceae, the rush family, are a monocotyledonous family of flowering plants. There are eight genera and about 400 species. Members of the Juncaceae are slow-growing, rhizomatous, herbaceous plants, and they may superficially resemble grasses. They often grow on infertile soils in a wide range of moisture conditions. The most well-known and biggest genus is Juncus. Most of the Juncus species grow exclusively in wetland habitats. A few rushes are annuals, but most are perennials. [more]

Mayacaceae

Mayaca is a genus of flowering plants, often placed in its own family, the Mayacaceae. In the APG II system of 2003, it is assigned to the Order Poales in the clade commelinids. The Cronquist system, of 1981, also recognised such a family and placed it in the order Commelinales in the subclass Commelinidae. The genus consists of probably fewer than a dozen species. [more]

Poaceae

The Poaceae (also known as the Gramineae) is a large and nearly ubiquitous family of monocot flowering plants. Members of this family are commonly called (land) grasses, although the term (land) "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes (Juncaceae) and sedges (Cyperaceae). As for the seagrasses, they all belong to the Alismatales, a different monocot order altogether. This broad and general use of the word "grass" has led to plants of the Poaceae often being called "true grasses". With over 10,025 currently accepted species, the Poaceae represent the fifth largest plant family. Only the Orchidaceae, Asteraceae, Fabaceae, and Rubiaceae have more species. [more]

Rapateaceae

[more]

Restionaceae

Restionaceae, also called restiads, is the botanical name for a family of rush-like flowering plants native to the Southern Hemisphere. The Restionaceae likely originated during the Cretaceous period, based on evidence from fossil pollen. [more]

Sparganiaceae

Sparganiaceae is the botanical name for a family of flowering plants. Such a family was previously recognized by most taxonomists. [more]

Thurniaceae

[more]

Typhaceae

Typhaceae is the botanical name for a family of flowering plants. Such a family has been recognized by most taxonomists. [more]

Xyridaceae

Xyridaceae is the botanical name of a family of flowering plants. Such a family has been recognized by many taxonomists and is known as the Yellow-eyed-grass Family. [more]

At least 666 species and subspecies belong to the Family Xyridaceae.

More info about the Family Xyridaceae may be found here.

References

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External links

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Bibliography

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Footnotes

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  1. Guofang Wu & Kai Larsen "Flagellariaceae". in Flora of China Vol. 24 Page 1. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org.

Sources

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Last Revised: August 24, 2012
2012/08/24 13:13:58