Austroderia is a genus of five species of tall perennial tussock grasses in the family Poaceae (order Poales), endemic to New Zealand. The plants are commonly known as toetoe, a name derived from Māori meaning “to shred or divide.” Growing to between 0.5 and 6 metres in height, Austroderia species form robust clumps recognisable by their waxy leaves, conspicuous veins between the midrib and leaf margin, and drooping white flower plumes that turn yellow through summer — a combination of traits that distinguishes them from the closely related South American pampas grasses (Cortaderia selloana and C. jubata).
The genus was first formally described in 2010 by Hans Peter Linder and Nigel P. Barker following a phylogenetic analysis of the subfamily Danthonioideae. Its five member species — A. toetoe, A. fulvida, A. splendens, A. richardii, and A. turbaria — had previously been classified within Cortaderia and were transferred to Austroderia in 2011. Austroderia is most closely related to Cortaderia of South America and to Chimaerochloa. Austroderia richardii serves as the type species of the genus.
The species occupy a range of coastal and riparian habitats across New Zealand: A. fulvida and A. richardii occur on both the North and South Islands, A. splendens is restricted to the upper North Island, A. toetoe to the lower North Island, and A. turbaria is endemic to the Chatham Islands. A. richardii has also become naturalised in Tasmania. Toetoe typically grows at beaches, along coastal cliffs, and beside streams.
Two South American congeners, Cortaderia jubata and C. selloana (pampas grass), were introduced to New Zealand as cattle fodder in the 19th century and are now regarded as invasive weeds that displace native toetoe populations.
Etymology
The genus name Austroderia was coined by combining “Cortaderia” with the Latin australis (“southern”), reflecting the genus’s southern-hemisphere distribution and its relationship with Cortaderia. The common name toetoe is Māori and literally means “to shred or divide,” with cognates across Polynesian languages where it describes splitting Pandanus leaves into strips. The flower stem has its own name, kākaho, which also has Polynesian-language cognates typically referring to stalks of Miscanthus floridulus.
Distribution
Austroderia is endemic to New Zealand, with species distributed across distinct geographic zones: A. fulvida and A. richardii on both the North and South Islands, A. splendens in the upper North Island, A. toetoe in the lower North Island, and A. turbaria restricted to the Chatham Islands. A. richardii has also naturalised in Tasmania. Plants grow in coastal and riparian settings — beaches, coastal cliffs, and stream margins.
Ecology
Native toetoe populations are threatened by competition from introduced South American pampas grasses (Cortaderia jubata and C. selloana), brought to New Zealand as cattle fodder in the 19th century. These invasive species are visually similar to toetoe but differ in having non-waxy leaves and erect, often pink or purple flower plumes; they spread aggressively and are regarded as serious environmental weeds across New Zealand.
Taxonomy Notes
Austroderia was segregated from Cortaderia in 2010 by Hans Peter Linder and Nigel P. Barker on the basis of phylogenetic analysis of Danthonioideae, and the five member species were formally transferred in 2011. The genus is placed in subfamily Danthonioideae of Poaceae, and is most closely related to Cortaderia (South America) and Chimaerochloa. The group’s distinctiveness had been recognised as early as 1853. Austroderia richardii is the type species.
