Althenia

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 and marine flowering plant comprising 6 or more species endemic{{cite book|editor=Klaus Kubitzki|title=Flowering Plants. Monocotyledons: Alismatanae and Commelinanae (except Gramineae) (The Families and Genera of Vascular Plants)

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, 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.

References

References

1. Hooker's J. Bot. Kew Gard. Misc. 7: 57. 1855 [[IPNI]]
2. "United States Department of Agriculture database".
3. Ito, Y., Nr. Tanaka, P. García-Murillo, A.M. Muasya (2016) [http://authors.elsevier.com/a/1SehA3m3nMlXJG 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]]'' '''98:''' 261-270.
4. "Genus Althenia".
5. Phillips, Edwin Percy. (1951). "The genera of South African flowering plants". Government Printer.
6. {{FloraBase
7. Hammer, Ulrich Theodore. (1986). "Saline Lake Ecosystems of the World". Springer London, Limited.
8. (2005). "Seagrasses: Biology, Ecology and Conservation". Springer-Verlag New York, LLC.
9. [[Yu Ito (botanist). Ito, Y.]], Nr. Tanaka, P. García-Murillo, A.M. Muasya (2016) [http://authors.elsevier.com/a/1SehA3m3nMlXJG 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]]'' '''98:''' 261-270.