Machaerina, commonly known as twigrush, is a genus of approximately 52–55 accepted species of rhizomatous perennial plants in the sedge family Cyperaceae, placed in the order Poales. The genus has a wide pantropical and warm-temperate distribution, with species native to tropical America, the West Indies, Malesia, Australia, and the Pacific region; Australia alone hosts around 17 species, of which 11 are endemic.
Plants in the genus are characterised by tufted culms that are erect and pithy, and leaves that are mainly basal, laterally compressed, distichous, and equitant at the base; leaf blades range from flat to terete depending on species. The inflorescence is panicle-like with culm-like involucral bracts, and spikelets are usually clustered, each bearing 1–5 bisexual flowers. The perianth is absent; stamens number three; the style is 3-fid and deciduous, with a thickened base that persists on the nut as a hemispherical to conical apex. The nut is trigonous to terete and prominently to obscurely 3-ribbed.
The genus formerly encompassed Baumea Gaudich., which is now treated as a synonym; both genera were also at times placed within Cladium sensu lato, though molecular work has shown that grouping to be unnatural. Among the species in cultivation or commonly encountered in the wild are Machaerina juncea, recognisable by all leaves reduced to flattened mucros, and Machaerina rubiginosa, distinguished by its brightly coloured orange to red-brown nuts and dense spikelet clusters.
Etymology
The genus name Machaerina derives from the Greek machaira, meaning a large knife, in reference to the blade-like shape of the leaves in the type species, Machaerina restioides.
Distribution
Machaerina species occur across tropical America, the West Indies, Malesia, Australia, and the broader Pacific region. Australia has the richest representation, with around 17 species recorded from all states, of which approximately 11 are endemic.
Taxonomy Notes
The genus formerly included Baumea Gaudich., now treated as a synonym of Machaerina (per PlantNET/APNI). Both genera were historically placed within Cladium sensu lato, but that arrangement is not supported by current phylogenetic data. GBIF records no separate authorship for the genus at the accepted name level.
