Hymenachne, synonymDallwatsonia, is a genus of widespread wetland plants in the grass family Poaceae. They are commonly known as marsh grasses.[5] They are distributed in tropical and subtropical regions of Asia, the Americas, and the Pacific Islands.[6] A species from the Americas, H. amplexicaulis, is well known in other parts of the world as an introduced and invasive species.[7]
Description
Hymenachne species are aquatic plants frequently found in marshes and other wet habitats. Their stems may be spongy with aerenchyma tissue.[8] The longest stems can reach 4 m (13 ft). They are perennial, sometimes with rhizomes. The leaves are linear or lance-shaped.[9] The inflorescence is usually a cylindrical, spike-shaped panicle, rarely with branches.[8]
Taxonomy
The genus Hymenachne was first described by Palisot de Beauvois in 1812.[10]Hymenachne is similar to the genus Sacciolepis,[8] first described in 1901. Both were formerly considered part of Panicum.[8] Many species placed in Hymenachne have previously been placed in Sacciolepis.[11]
In 1992, Bryan Kenneth Simon [es] described a new genus Dallwatsonia for a single new Australian species he called Dallwatsonia felliana. The genus was named for the Australian botanists Michael Dallwitz and Leslie Watson.[12] In 2014, ten further species were transferred from Panicum to Dallwatsonia by José Ramón Grande Allende, who noted that Dallwatsonia was closely related to Hymenachne, but could be distinguished by hollow rather than filled culms.[13] However, a molecular phylogenetic study published in 2014 supported the synonymy of Dallwatsonia and Hymenachne,[14] a conclusion also supported in a 2019 study.[15] As of November 2024[update], Plants of the World Online accepted Dallwatsonia as a synonym of Hymenachne.[3]
Species
As of November 2024[update], the following species were accepted:[3][16]
^Acosta, J.M.; Scataglini, M.A.; Reinheimer, R. & Zuloaga, F.O. (2014). "A phylogenetic study of subtribe Otachyriinae (Poaceae, Panicoideae, Paspaleae)". Plant Systematics and Evolution. 300 (10): 2155–2166. Bibcode:2014PSyEv.300.2155A. doi:10.1007/s00606-014-1034-8. hdl:11336/18975.
^Acosta, Juan M.; Zuloaga, Fernando O. & Reinheimer, Renata (2019), "Nuclear phylogeny and hypothesized allopolyploidization events in the Subtribe Otachyriinae (Paspaleae, Poaceae)", Systematics and Biodiversity, 17 (3): 277–294, Bibcode:2019SyBio..17..277A, doi:10.1080/14772000.2019.1572035, hdl:11336/116214