Poales

Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
(unranked):	Commelinids
Order:	Poales Small
families
See text

Billbergia pyramidalis of familyBromeliaceae

Setaria verticillata from familyPoaceae

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.

Recent studies (e.g., Bremer, 2000) place the origin of the Poales in South America nearly 115 million years ago. The earliest known fossils include pollenand fruits that have been dated to the late Cretaceous. 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:

• order Poales

  family Anarthriaceae

  family Bromeliaceae

  family Centrolepidaceae

  family Cyperaceae

  family Ecdeiocoleaceae

  family Eriocaulaceae

  family Flagellariaceae

  family Joinvilleaceae

  family Juncaceae

  family Mayacaceae

  family Poaceae

  family Rapateaceae

  family Restionaceae

  family Thurniaceae

  family Typhaceae

  family Xyridaceae

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):

• order Poales

  family Anarthriaceae

  family Centrolepidaceae

  family Cyperaceae

  family Ecdeiocoleaceae

  family Eriocaulaceae

  family Flagellariaceae

  family Hydatellaceae (now transferred out of the monocots; recently discovered to be an 'early-diverging' lineage of flowering plants.)

  family Joinvilleaceae

  family Juncaceae

  family Poaceae

  family Prioniaceae

  family Restionaceae

  family Sparganiaceae (now included in family Typhaceae.)

  family Thurniaceae

  family Typhaceae

  family Xyridaceae

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 theHutchinson system (first edition, first volume, 1926), Glumiflorae in the Wettstein system (last revised 1935) or Glumaceae in the Bentham & Hooker system (third volume, 1883).

[edit]Uses

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:

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

[edit]References