Australian winged iris with a purple twist

This is a native Australian iris relative called Diplarrena latifolia 'Amethyst Fairy'. It looks a lot like the better known Dietes, or False Iris, with most species from Africa but one from Lord Howe Island. Or perhaps Morea, the Cape Tulip, a commonly grown iris-like plant from Africa through to Mediterranean and Asia. 

There are at most (see below) two species of Diplarrena, both from eastern Australia. Diplarrena moraea is widespread in south-eastern New South Wales, Victoria and Tasmania, and Diplarrena latifolia only grows naturally in Tasmania where it can dominate threatened subalpine 'rushlands' (swampy areas with mostly sedges, grasses and the like).

Oh, and watch out for the misspelling of the genus name as 'Diplarrhena', which might seem more logical given its etymology (again, see below).

The Australian Cultivar Registration Authority (ACRA), tracks the cultivar 'Amethyst Fairy' back to a wild population of Diplarrena latifolia from Tasmania. The name is a reference to the purple stripes and patches of colour in the centre of the flower, and to the dainty wing-like nature of the white petals. 

While I've accepted two species here, some consider Diplarrena latifolia to be a local variant of Diplarrena moraea. So only one species. In that case this cultivar is either Diplarrena moraea 'Amethyst Fairy' or sometimes simply Diplarrena 'Amethyst Fairy'.

Whether one species or two, they are all commonly called Butterfly Flag or White Iris, a reflection of their similarity to the best known member of its plant family Iridaceae, the iris or 'flag'. 

As with all Diplarrena, and like the closely related Dietes, the flower lasts only a day but is soon replaced by the next.  These photos were taken in late October, a month after they were planted in the Greening Cities garden, one of the display gardens in the Australian Garden at Royal Botanic Gardens Cranbourne (which is a lot of 'gardens').

So what's going on in those flowers? Like all members of the iris family there are six petal-like segments, with the outer ones in this genus soft, white and spreading. The inner segments are the furled, colourful bits in the middle!

Inside there are three male bits (stamens), two of them fertile (the yellowish blurs in the two pictures above) and one shorter, without a pollen-bearing anther. The genus name is from the Ancient Greek word for double (diplo) and male (arrhen). Hence two functioning stamens, and the temptation to add an 'h' to the name.

The female part is longer than the stamens and three-branched. I'm presuming that the frosty surfaced structure where the inner floral parts meet in the picture above is one of the stigma branches?