Proto Polynesian: *Kuta
REFLEXES IN SOME POLYNESIAN LANGUAGES:
Tongan: Kuta, Kutu (Eleocharis dulcis, "Chinese water chestnut", Cyperaceae); Kuta "mats woven from kuta culms".
Samoan: 'utu'utu (Eleocharis dulcis "Chinese water chestnut ", Cyperaceae)
Mangaian: Kuta (Reed sp. - Eleocharis sp.?, Cyperaceae).
Maori: Kuta (Eleocharis sphaculata, "Bamboo spike sedge", and Kutakuta (Schoenoplectus tabernaemontani, "Soft-stem bulrush ", Cyperaceae)

COGNATE REFLEXES IN SOME OTHER AUSTRONESIAN LANGUAGES
Fijian: Kuta (Eleocharis interstincta, "Knotted spikerush ", Cyperaceae)

The prototypical kuta is probably the Fijian "knotted spike rush", Eleocharis interstincta. As with its New Zealand counterpart, the culm (the stem that you see above the water – the true leaves of the plant are very small, close to the base of the culm and usually well hidden from view, a couple of feet below the water level) is segmented with septa (internal divisions) that are visible on the outside. Its culms are up to 2 m in length.

The Samoan and Tongan counterpart, the so-called "Chinese water chestnuts", with edible rhizomes, and culms growing to about 1 1/2 m tall, is found throughout the tropics, and is native to several of the Pacific Islands, including Fiji, Tonga (where it is especially associated with the island of Vava'u) and Hawaii, as well as parts of the United States. It is similar in appearance to the Fijian kuta, to which it is closely related botanically, except for the smooth rather than ringed surface of the culms, and occupies a similar exological niche, able to thrive in deeper water than most lake and river-margin plants. It was therefore a natural candidate for the name bestowed on it. The rhizomes of this plant are eaten in many parts of the world; they are good sources of fibre and some minerals and vitamins. The dried culms are used for weaving in Tonga, in much the same way as those of the closely related New Zealand kuta. In Tonga the word kuta denotes both the sedge, Eleocharis dulcis, and mats woven from the dried culms. Kutu, cognate with the Samoan word 'utu'utu, is an alternative name for the plant only. The Samoan name may reflect a residual memory of the Fijian species, as a reduplicated form often indicates likeness or similarity to the object named by the word root.

Although edible rhizomes are called "Chinese water chestnuts", these plants are not related to the "true" water chestnuts, three species of the genus Trapa (Lythraceae), which are not sedges, but members of the same order of plants as the pōhutukawa. The chestnuts that grow on trees (Castanea species) are botanically quite distant from both their sets of English-language namesakes.