# Alisma
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> Source: https://en.wikipedia.org/wiki/Alisma
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{{Short description|Genus of aquatic plants}}
{{For|the birth control pill|Ethinylestradiol/cyproterone acetate}}
{{Automatic taxobox
|image = Alisma plantago-aquatica20090812 259.jpg
|image_caption = ''[Alisma plantago-aquatica](/source/Alisma_plantago-aquatica)''
|taxon = Alisma
|authority = [L.](/source/Carl_Linnaeus)
|subdivision_ranks = Species
|subdivision = See text
}}
'''''Alisma''''' is a genus of [flowering plant](/source/flowering_plant)s in the family [Alismataceae](/source/Alismataceae), members of which are commonly known as '''water-plantains'''. The genus consists of [aquatic plant](/source/aquatic_plant)s with [leaves](/source/Leaf) either floating or submerged, found in a variety of still water habitats around the world (nearly worldwide).[{{cite web | url = http://efloras.org/florataxon.aspx?flora_id=1&taxon_id=101042 | work = [Flora of North America](/source/Flora_of_North_America) | title = Alisma }}][[http://apps.kew.org/wcsp/namedetail.do?name_id=294751 Kew World Checklist of Selected Plant Families]] The [flower](/source/flower)s are [hermaphrodite](/source/plant_reproductive_morphology), and are arranged in [panicle](/source/panicle)s, [raceme](/source/raceme)s, or [umbel](/source/umbel)s. ''Alisma'' flowers have six [stamen](/source/stamen)s, numerous free [carpel](/source/carpel)s in a single whorl, each with 1 ovule, and subventral styles. The fruit is an [achene](/source/achene) with a short beak.
The nineteenth century [British](/source/British_people) art and social critic [John Ruskin](/source/John_Ruskin) believed that the particular curve of the leaf-ribs of ''Alisma'' represented a model of '[divine proportion](/source/Golden_ratio)' and helped shape his theory of [Gothic architecture](/source/Gothic_architecture).[J. Mordaunt Crook, "Ruskinian Gothic" in The Ruskin Polygon: Essays on the Imagination of John Ruskin ed. John Dixon Hunt and Faith M. Holland (Manchester University Press, 1982) pp. 65–93.]
{{lang|ga|Copóg Phádraig}} ("Patrick's leaf") is the Irish name for the water-plantain. It is reputed to ward off fairies.[{{Cite book |last=MacKillop |first=James |url=https://www.oxfordreference.com/display/10.1093/acref/9780198609674.001.0001/acref-9780198609674-e-1129?rskey=2KZe0K&result=1129 |title=A Dictionary of Celtic Mythology |publisher=Oxford University Press |year=2004 |isbn=9780198609674}}]
Water plantains are perennial plants. These herbs are usually emergent plants {{convert|0.1-1|m|in|sigfig=1|abbr=on}} high. They have broad leaves that can be either tapered or rounded at the base. When submerged, the plant produces ribbon-like leaves. Inflorescences are highly branched. They produce [whorls](/source/Whorl_(botany)) of perfect flowers either white or pinkish. The fruits are flat-sided nutlets {{convert|2.5-3|mm|in|abbr=on}} in length. These herbs usually flower in late May to early September, but this can vary with conditions.[Gleason and Cronquist (1991); Fernald (1970); Voss (1972).]
Water-plantains are [wetland](/source/wetland) plants and found in saturated soils and shallow water as well as [marsh](/source/marsh)es, wooded [swamp](/source/swamp)s, shrub swamps and flooded farmland. When introduced to an area, water plantain can rapidly reproduce.
==Species and subspecies==
The following taxa are recognized as of May 2014: