''Hymenachne'' is a genus of widespread

wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

plants that is in the

grass family Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns and ...

. They may be known commonly as marsh grasses. They are distributed in tropical and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

regions of Asia, the Americas, and the

Pacific Islands Collectively called the Pacific Islands, the islands in the Pacific Ocean are further categorized into three major island groups: Melanesia, Micronesia, and Polynesia. Depending on the context, the term ''Pacific Islands'' may refer to one of se ...

.Clarkson, J. R., et al. (2011)
A report of hybridisation in ''Hymenachne'' (Poaceae, Panicoideae) with description of ''Hymenachne'' × ''calamitosa'', a new species of hybrid origin from tropical Australia.
''Telopea'' 13(1-2), 105-14. A species from the Americas, ''H. amplexicaulis'', is well known in other parts of the world as an introduced and

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

. ''Hymenachne'' is similar to genus ''

Sacciolepis ''Sacciolepis'' is a genus of plants in the grass family. Cupscale grass is a common name for plants in this genus. They are widespread in tropical and warmer temperate regions. Many are native to Africa, with others in Asia, Australia, and th ...

''. Both were formerly considered part of '' Panicum''.''Hymenachne''.
Flora of China. ''Hymenachne''

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

s frequently found in marshes and other wet habitats. Their stems are spongy with aerenchyma tissue. The longest stems can reach 4 meters. They are perennial, sometimes with

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

s. The leaves are linear or lance-shaped.''Hymenachne''.
Grassbase - The World Online Grass Flora. The inflorescence is usually a

cylindrical A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infini ...

, spike-shaped

panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a panicle are of ...

, rarely with branches.

Diversity

; Accepted speciesKew World Checklist of Selected Plant Families
/ref>GRIN Species Records of ''Hymenachne''.
Germplasm Resources Information Network (GRIN) * ''

Hymenachne amplexicaulis ''Hymenachne amplexicaulis'', also known as West Indian marsh grass in the US, Olive hymenachne in Australia, and hereafter referred to as hymenachne, is New World species in the genus ''Hymenachne ''Hymenachne'' is a genus of widespread wetla ...

'' – West Indian marsh grass, olive hymenachne - West Indies; Latin America from Mexico to Uruguay; naturalized in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, parts of Asia, Florida * '' Hymenachne assamica'' -

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, Assam,

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...

, Thailand * ''

Hymenachne donacifolia ''Hymenachne'' is a genus of widespread wetlands plants that is in the grass family. They may be known commonly as marsh grasses. They are distributed in tropical and subtropical regions of Asia, the Americas, and the Pacific Islands.Clarkson, J. ...

'' - Cuba, Puerto Rico, Trinidad; Latin America from

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. The republic of Honduras is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Oce ...

to Paraguay * ''

Hymenachne grumosa ''Hymenachne'' is a genus of widespread wetlands plants that is in the Poaceae, grass family. They may be known commonly as marsh grasses. They are distributed in tropics, tropical and subtropics, subtropical regions of Asia, the Americas, and th ...

'' - Paraguay, Uruguay, Brazil, Argentina * ''

Hymenachne patens ''Hymenachne'' is a genus of widespread wetlands plants that is in the Poaceae, grass family. They may be known commonly as marsh grasses. They are distributed in tropics, tropical and subtropics, subtropical regions of Asia, the Americas, and th ...

'' -

( Anhui, Fujian, Jiangxi) * '' Hymenachne pernambucense'' - Paraguay, Uruguay, Brazil, Argentina * ''

Hymenachne wombaliensis ''Hymenachne'' is a genus of widespread wetlands plants that is in the grass family. They may be known commonly as marsh grasses. They are distributed in tropical and subtropical regions of Asia, the Americas, and the Pacific Islands.Clarkson, J. ...

'' - Zaïre ; formerly included see '' Panicum

Pennisetum ''Pennisetum'' is a widespread genus of plants in the grass family, native to tropical and warm temperate regions of the world. They are known commonly as fountaingrasses (fountain grasses).Sacciolepis ''Sacciolepis'' is a genus of plants in the grass family. Cupscale grass is a common name for plants in this genus. They are widespread in tropical and warmer temperate regions. Many are native to Africa, with others in Asia, Australia, and th ...

References

{{Taxonbar, from=Q2198236 Panicoideae Poaceae genera