Rytidosperma is a genus of tufted perennial grasses in the family Poaceae (order Poales), described by Steudel in 1854. The genus is commonly known as wallaby grasses and comprises roughly 80 species, with the greatest diversity in Australia and New Zealand and smaller contingents in insular Southeast Asia, southern South America (Chile and Argentina), Hawaii, and Easter Island.
Plants are tufted perennials forming compact to spreading clumps. The inflorescence is an open to spike-like contracted panicle, occasionally reduced to a raceme, with few spikelets that are white or pale at maturity. Spikelets are pedicellate and disarticulate above the glumes and between the florets, bearing 3–9 bisexual florets. The glumes are subequal, acute, broad-keeled, longer than the lemma, faintly 5–7-nerved, and often streaked with purple; their margins are translucent and gape at maturity to expose the hairy florets. Lemmas are soft to leathery, rounded on the back and clothed with hairs arranged in tufts, transverse rows, or rows of tufts; the apex is deeply bilobed with lobes usually drawn out into slender bristles, and a central awn arises in the sinus, typically reflexed or geniculate and twisted. The callus is bearded and the palea is 2-keeled with ciliate keels.
The genus has undergone considerable taxonomic revision. Several former Rytidosperma species have been transferred to related genera including Austrodanthonia, Notodanthonia, Joycea, Erythranthera, Merxmuellera, and Tenaxia, all of which are treated as synonyms under the broader circumscription accepted by GBIF. In Australia, 27 species are recognised across all states except the Northern Territory.
Distribution
Rytidosperma is predominantly an Australasian genus, with approximately 27 species native to Australia (all states except the Northern Territory) and further diversity in New Zealand. A smaller number of species extend into insular Southeast Asia, southern South America (Chile and Argentina), and isolated Pacific islands including Hawaii and Easter Island.
Taxonomy Notes
Rytidosperma Steud. was published in Synopsis Plantarum Glumacearum 1: 425 (1854). The genus has a complex synonymy: Austrodanthonia H.P.Linder, Notodanthonia Zotov, Joycea H.P.Linder, Erythranthera Zotov, Pyrrhanthera Zotov, Thonandia H.P.Linder, and Monostachya Merr. are all treated as synonyms. Additionally, some former Rytidosperma species have been transferred to Merxmuellera and Tenaxia.
