''Althenia'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

aquatic plants Aquatic plants, also referred to as hydrophytes, are vascular plants and non-vascular plants that have adapted to live in aquatic environments ( saltwater or freshwater). In lakes, rivers and wetlands, aquatic vegetations provide cover for aquat ...

of the family

Potamogetonaceae The Potamogetonaceae, commonly referred to as the pondweed family, is an aquatic family of monocotyledonous flowering plants. The roughly 110 known species are divided over five genera. The largest genus in the family by far is '' Potamogeton'', ...

. This has long been a group of two species in the Mediterranean Europe and South Africa, but in 2016 was revised to include an Australasian relative, ''Lepilaena''. The genus is named after the agronomist

Jean Althen Jean-Baptiste Joannis Althen, better simply known as Jean Althen (Hovhannès Althounian; 1709–1774), was an Armenian agronomist from Safavid Iran who developed the cultivation of madder in France. Although the plant had been present in the regi ...

Description

This genus is made up of aquatic herbs. The bristle-like leaves are clustered at the nodes. The wider bases produce broad ligules. The flowers are unisexual. The male flowers have a perianth made of three minute scales and have a single stamen. The female flowers have a perianth made of one to three segments. The gynoecium has three carpels with a single pendulous ovule in each ovary. The filiform styles gradually pass into the carpels and the stigmas are large and oblique. The mature carpels are oblique and compressed with a winged or thickened margin. The seeds are pendulous, oblong and compressed. The embryo is straight.

Species

:* '' Althenia australis'' (aquatic) :* '' Althenia bilocularis'' (aquatic) :* '' Althenia cylindrocarpa'' (brackish water, marine) :* '' Althenia filiformis'' :* '' Althenia hearnii'' :* '' Althenia marina'' (marine) :* '' Althenia orientalis'' :* '' Althenia patentifolia'' :* '' Althenia preissii'' (aquatic) :* '' Althenia tzvelevii''

Lepilaena

''Lepilaena'' was a genus of

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

and marine

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

comprising 6 or more species

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to coastal and

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

or alkaline inland waters of temperate

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

, and

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. The species are appended with common names that derive from their description as water-mats; for example, ''L. australis'' is referred to as Austral water-mat and ''L. marina'' as Sea water-mat. Interpretation of molecular evidence for this poorly studied genus suggests a close affinity with ''

Zannichellia ''Zannichellia'' (common name horned pondweed) is a genus of submerged aquatic flowering plant, with threadlike leaves and tiny flowers. It is fully adapted to an aquatic life cycle, including underwater pollination Pollination is the transfe ...

'', another genus of aquatic plants. Two species are noted for their occurrence in marine environs, ''L. cylindrocarpa'' and ''L. marina'', in estuaries and tidal flats. ''L. cylindrocarpa'' is also found in a variety of brackish inland waters of mainland Australia. Other species may be found in habitats of fresh to brackish, still or slowly moving, coastal or inland waters. Based on the molecular and morphological evidence, all the species have been transferred to the genus ''Althenia'' in 2016. Ito, Y., Nr. Tanaka, P. García-Murillo, A.M. Muasya (2016
A new delimitation of the Afro-Eurasian plant genus ''Althenia'' to include its Australasian relative, ''Lepilaena'' (Potamogetonaceae) – evidence from DNA and morphological data
''

Molecular Phylogenetics and Evolution ''Molecular Phylogenetics and Evolution'' is a peer-reviewed scientific journal of evolutionary biology and phylogenetics. The journal is edited by E.A. Zimmer. Indexing The journal is indexed in: * EMBiology *Journal Citation Reports *Scopus ...

'' 98: 261-270.

References

External links

Flora of Western Australia
* * {{Taxonbar, from1=Q4736673, from2=Q144062 Aquatic plants Potamogetonaceae Alismatales genera