Trimezia martinicensis is a species of bulbous plant in the family Iridaceae. Originally from South America and the West Indies, it is now widely naturalized throughout the tropics.[1] Common names include Martinique trimezia, yellow walking iris[2] and forenoon yellow flag.[3]
Trimezia martinicensis is closely related to T. steyermarkii, with which it has been widely confused. Clive Innes describes T. martinicensis as having a brown mark at the base of each outer tepal, whereas T. steyermarkii has brownish-purple bands. In Kubitzki & Huber (1998), the flowers of T. martinicensis are shown as opening less widely than those of T. steyermarkii. The inner tepals of both species are S-shaped in cross-section; those of T. martinicensis are more-or-less upright (Innes describes them as "folded inwards"), whereas those of T. steyermarkii bend outwards into a more elongated shape so that the top of the S is not visible from above.[4] A diagnostic feature is that the style crests of T. martinicensis are short, whereas those of T. steyermarkii are longer,[4] about 3- long, comparable in length to its anthers, which are about 4abbr=onNaNabbr=on long.[5] Another difference is that the leaves of T. martinicensis are narrower, only about 1.3abbr=onNaNabbr=on wide, whereas those of T. steyermarkii are 2.5- wide.