''Dietes robinsoniana'', the Lord Howe wedding lily, is found naturally only on

Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland P ...

. It grows on cliff faces, often in exposed situations. Found also on forest margins and the tops of

Mount Gower Mount Gower (also known as Big Hill), is the highest mountain on Australia's subtropical Lord Howe Island in the Tasman Sea. With a height of above sea level, and a relatively flat summit plateau, it stands at the southern end of Lord Howe, just ...

and

Mount Lidgbird Mount Lidgbird, also Mount Ledgbird and Big Hill, is located in the southern section of Lord Howe Island, just north of Mount Gower, from which it is separated by the saddle at the head of Erskine Valley, and has its peak at above sea level. ...

and behind the beaches on Lord Howe Island. It is one of the world's most intriguing and remarkable biogeographic disjunctions, with its nearest phylogenetic relatives occurring in Africa. Dietes robinsoniana qtl1

This is the largest plant in the genus ''

Dietes ''Dietes'' is a genus of rhizomatous plants of the family Iridaceae, first described as a genus in 1866. Common names include wood iris, fortnight lily, African iris, Japanese iris and butterfly iris, each of which may be used differently in diff ...

''. It does not tolerate cold temperatures.Cundall. P., (2008) Native Plants:The definitive guide to Australian plants, Global Book Publishing Lane Cove, N.S.W, page 65, It is an uncommon plant, though it may be locally abundant in certain sites. Growing up to tall, the leaves are sword-shaped or linear, 4 to 7 cm wide. Flowering occurs from September to December. The flowers are white with yellow, lasting for one day only.
Link to a flower photo:
Flat triangular seeds form in a roundish shaped capsule, 3 to 4 cm long. The black seeds are around 10 mm long.

References

Iridaceae Endemic flora of Lord Howe Island Plants described in 1871 Garden plants Taxa named by Ferdinand von Mueller Taxa named by Charles Moore {{Iridaceae-stub