Theflowers are typically small, enclosed by bracts, and arranged ininflorescences (except in three species of the genusMayaca, which possess very reduced, one-flowered inflorescences). The flowers of many species are wind pollinated; the seeds usually containstarch.
The earlierAPG 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 familiesPrioniaceae (now included in Thurniaceae),Sparganiaceae (now in Typhaceae), andHydatellaceae (now transferred out of the monocots; recently discovered to be an 'early-diverging' lineage of flowering plants).
The earliest fossils attributed to the Poales date to the lateCretaceous 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 inSouth America. The earliest known fossils includepollen and fruits.
The phylogenetic position of Poales within the commelinids was difficult to resolve, but an analysis using completechloroplast DNA found support for Poales as sister group ofCommelinales plusZingiberales.[2] Major lineages within the Poales have been referred to asbromeliad,cyperid,xyrid,graminid, andrestiid 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]
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 staplesbarley,maize,millet,rice, andwheat 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.
^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.ISSN0040-0262.
Judd, W. S., C. S. Campbell, E. A. Kellogg, P. F. Stevens, M. J. Donoghue (2002).Plant Systematics: A Phylogenetic Approach, 2nd edition. pp. 276–292 (Poales). Sinauer Associates, Sunderland, Massachusetts.ISBN0-87893-403-0 .
Linder, H. Peter; Rudall, Paula J. (2005). "Evolutionary History of the Poales".Annual Review of Ecology, Evolution, and Systematics.36:107–124.doi:10.1146/annurev.ecolsys.36.102403.135635.
Small, J. K. (1903).Flora of the Southeastern United States, 48.New York,United States
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