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 different regions for one or more of the six species within the genus.

Most species are native to southern and central Africa, with one (Dietes robinsoniana) native to Lord Howe Island off the coast of Australia. A few species have become naturalized in other parts of the world.These plants were formerly placed in the genus Moraea, but were reclassified because they are rhizomatous. Like Moraea, they differ from Iris in having flowers with six free tepals that are not joined into a tube at their bases.

Some references mention the species Dietes vegeta or D. vegeta variegata, springing from some confusion with Moraea vegata (which grows from a corm, not a rhizome). The name D. vegeta is commonly misapplied to both D. grandiflora or D. iridioides.
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