''Pseudoraphis spinescens'', called spiny mudgrass or Moira grass is a

rhizomatous 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 ...

and

stolon In biology, a stolon ( from Latin ''wikt:stolo, stolō'', genitive ''stolōnis'' – "branch"), also known as a runner, is a horizontal connection between parts of an organism. It may be part of the organism, or of its skeleton. Typically, animal ...

iferous aquatic or semi-aquatic perennial

grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and spe ...

, with ascending stems forming loose, floating mats in water to 1 m deep or more, or with stems to 50 cm high when not submerged. Moira grass (''Pseudoraphis spinescens'') was first described in 1810 by

Robert Brown Robert Brown may refer to: Robert Brown (born 1965), British Director, Animator and author Entertainers and artists * Washboard Sam or Robert Brown (1910–1966), American musician and singer * Robert W. Brown (1917–2009), American printmaker ...

as ''Panicum spinescens'', and subsequently transferred to ''

Pseudoraphis ''Pseudoraphis'' is a genus of Asian and Australian plants in the grass family, commonly known as mudgrasses.Watson, L. and M. J. Dallwitz. 1992 onwards''Pseudoraphis'' Griff.The Grass Genera of the World.Joyce W. Vickery in 1950. ''Pseudoraphis spinescens'' is native to floodplains in Asia and Australasia, it is a C4 species, requiring seasonal cycles of prolonged, deep flooding interspersed with drying to achieve maximum growth and reproduction. Between flood events, ''P. spinescens'' forms a deep thatch of collapsed dry stems until flooding recurs and growth recommences. A study in southeastern Australia found that ''P. spinescens'' does not have a viable long-lived seed bank in floodplain soil, presumably regenerating from vegetative propagules and rootstocks. In the Murray-Darling Basin, prior to regulation of the

Murray River The Murray River (in South Australia: River Murray; Ngarrindjeri language, Ngarrindjeri: ''Millewa'', Yorta Yorta language, Yorta Yorta: ''Dhungala'' or ''Tongala'') is a river in Southeastern Australia. It is List of rivers of Australia, Aust ...

, extensive ''Pseudoraphis spinescens'' dominated floodplain marshes existed in areas that were typically seasonally flooded for 5–9 months duration in most years, to a minimum water depth of 0.5 m, and completely dry during late summer and autumn. ''Pseudoraphis spinescens'' is an important species in floodplain marsh ecosystems, providing habitat and food for a range of fauna including birds, frogs, fish and insects, and key ecosystem functions such as

nutrient cycling A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyc ...

and primary productivity.

Significance in the Murray Darling Basin

The Barmah Forest Ramsar site on the

floodplain in northern

Victoria (Australia) Victoria, commonly abbreviated as Vic, is a States and territories of Australia, state in southeastern Australia. It is the second-smallest state (after Tasmania), with a land area of ; the second-most-populated state (after New South Wales), ...

is a bioregionally significant seasonal floodplain wetland, historically the most extensive areas of Moira grass (''Pseudoraphis spinescens'') plains in the Murray-Darling Basin occurred in this region. The extent of floodplain marshes in Barmah forest has been severely reduced since European settlement, with the introduction of large grazing animals and the diversion of water from the

. Floodplain areas previously dominated by aquatic species such as Moira grass (''Pseudoraphis spinescens''), common reed (''

Phragmites australis ''Phragmites australis'', known as the common reed, is a species of flowering plant in the grass family Poaceae. It is a wetland grass that can grow up to tall and has a cosmopolitan distribution worldwide. Description ''Phragmites australis' ...

'') and cumbungi ( ''Typha'' spp.) are now covered with species adapted to lower levels of flooding, mainly river red gums (''

Eucalyptus camaldulensis ''Eucalyptus camaldulensis'', commonly known as river red gum, is a flowering plant in the family Myrtaceae, and is Endemism, endemic to Australia. It is a tree with smooth white or cream-coloured bark, lance-shaped or curved adult leaves, flow ...

'') and giant rush (''

Juncus ingens ''Juncus ingens'', common name giant rush, is a dioecious perennial with horizontal or ascending rhizomes. The stems are erect, dull green, (1.5–2–5 m tall and 4–10 mm in diameter, cataphylls are to 40 cm or more long. The inflorescence is ...

''). A 2017

CSIRO The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency that is responsible for scientific research and its commercial and industrial applications. CSIRO works with leading organisations arou ...

analysis found that the management changes most likely to result in an increase in the current extent of Moira grass plains in

Barmah National Park The Barmah National Park, formerly Barmah State Park, is a national park located in the Hume (region), Hume region of the States and territories of Australia, Australian state of Victoria (Australia), Victoria. The park is located adjacent to th ...

, over the next 10 years are reducing grazing, and increasing flood duration and depth. Most significantly, the removal of the large population of

feral horse A feral horse is a free-roaming horse of domesticated stock. As such, a feral horse is not a wild animal in the sense of an animal without domesticated ancestors. However, some populations of feral horses are managed as wildlife, and thes ...

s in

is estimated to result in a 61% increase in the current extent of the Moira grass plains. An analysis of the rate of vegetation change in Barmah Forest, published in 2014, predicted that if no management actions were taken, ''Pseudoraphis spinescens'' dominated grassy wetlands would become locally extinct by 2026.

:Water regime for vigorous growth ::Maintenance: Flooding for vigorous grasslands of ''Pseudoraphis spinescens'' should be seasonal, annual and fairly predictable, with a seasonal dry phase. Small variations in water regime favour its competitors, leading to a compositional or structural change. Growth after flooding is from rootstock, rather than fragments or seeds. :::Frequency of flooding: Annual or near annual, i.e. every year, occasionally once in two years. :::Depth of flooding: Initially depth is not critical: flood peak may exceed 2 m, then water levels should stabilise at about 1 to 1.5 m for two to three months, but not less than 0.5 m until drying out. :::Duration of flooding: On average about seven months. Can tolerate less: no less than five months if starting in winter, and no less than three months if starting in spring. Can tolerate longer: but durations of 10 months should happen rarely and not in sequential years. :::Timing of flooding: Floods can start at any time from winter to early spring. ::Regeneration: Importance of seeds and seed bank is not known. No information on seedling growth. ::Critical flood interval: Reflood after two years to maintain vigour. ''Pseudoraphis spinescens'' grasslands should not be without flooding for more than five years.

References

External links

Atlas of Living Australia: ''Pseudoraphis spinescens''

Flora of Victoria: ''Pseudoraphis spinescens''
{{Taxonbar, from=Q10885615 Flora of Australia Flora of Victoria (state) Panicoideae