Ranunculus lyallii (Mountain buttercup, Mount Cook buttercup, or, although not a lily, Mount Cook lily), is a species of Ranunculus (buttercup), endemic to New Zealand, where it occurs in the South Island and on Stewart Island at altitudes of 700–1,500 m.[1][2] R. lyallii is the largest species in the genus Ranunculus, growing over a metre in height.

Contemporary botanist Sir Joseph Hooker, (1817–1911), noted in his Flora Antarctica:

Among his many important botanical discoveries in this survey was that of the monarch of all buttercups, the gigantic white-flowered Ranunculus lyallii, the only known species with peltate leaves, the 'water-lily' of the New Zealand shepherds.--Joseph Dalton Hooker (1895) 33 Journal of Botany, p. 209.It is a herbaceous perennial plant growing to 60–100 cm tall (the largest species of buttercup), with a stout rhizome.

Other companies connected with the airline used the same logo until the Mount Cook Group was disbanded in 1989.

[5] The iconic flower has featured on New Zealand Post stamps as early as 1936 and repeatedly in later decades as part of sets relating to conservation and scenery.