Libertia grandiflora

Libertia grandiflora, the tukauki or mikoikoi, is a flowering plant in the family Iridaceae. The species is endemic to New Zealand. It is a clump-forming herbaceous perennial growing to tall by broad, with leathery linear leaves and panicles of white flowers in spring, followed by seed capsules. The Latin "grandiflora" means large flowered.
In cultivation this plant requires a sunny, sheltered location and protection from winter frosts. It has gained the Royal Horticultural Society's Award of Garden Merit.