Trimezia
Trimezia is a genus of flowering plants in the family Iridaceae, native to the warmer parts of southern Mexico, Central America, South America, Florida, and the West Indies. Trimezia is placed in the tribe Trimezieae. The division of the tribe into genera has varied considerably. In one approach, it contains only the genus Trimezia, which then includes the genera Neomarica, Pseudotrimezia and Pseudiris. In other approaches, two to five genera are recognized, sometimes also including the genus Deluciris.
The English names walking iris, apostle's iris and apostle plant have been used for many species, regardless of the generic placement. New plantlets form at the end of the flower spikes; after flowering, the spikes fall over and a new plant grows, so the plant "walks". Names including "apostle" refer to the incorrect belief that plants do not flower until 12 or more leaves are present.
Description
The rootstock is variously described as an elongated corm or a rhizome. Plants vary in height from about in the case of T. pusilla to in the case of T. spathata subsp. sincorana. Linear to lanceolate leaves grow from the base of the plant. Most species have flowers in some shade of yellow. The six tepals are arranged in two series. The outer tepals are larger than the inner ones ; both may have brown-purple markings at the base. The stamens have free filaments. The style is divided into three branches, each of which usually has two lobes.Taxonomy
The genus Trimezia was first published with an appropriate description by William Herbert in 1844. Herbert attributed the name to Salisbury, whose use he described as "absque charactere". The genus name is derived from the Greek words τρεῖς,, meaning 'three' and μείζων,, meaning 'greater', referring to the outer three tepals being much larger than the inner three.Trimezia is placed in the tribe Trimezieae of the subfamily Iridoideae. The number of genera into which the tribe is divided has varied considerably. Three genera were used before 2008: Trimezia, Neomarica and Pseudotrimezia. Some sources used all three; others combined Trimezia and Neomarica but retained Pseudotrimezia. A further genus, Pseudiris, was published in 2008. Molecular phylogenetic studies have shown that although the tribe is monophyletic, the genera as traditionally used, based on morphological characteristics, are not. Three of the four main clades found in these analyses combine species from more than one genus. One response to these findings, adopted as of 2025 by Plants of the World Online, is to combine genera; thus Deluciris, Neomarica, Pseudiris and Pseudotrimezia are all placed within Trimezia. An alternative approach, retaining the traditional genera but with changed circumscriptions, was put forward in 2018; an additional new genus, Deluciris, was also created within the tribe.
| Examples of alternative divisions of Trimezieae | Examples of alternative divisions of Trimezieae | Examples of alternative divisions of Trimezieae | Examples of alternative divisions of Trimezieae | Examples of alternative divisions of Trimezieae |
| Ravenna | Chukr & Giulietti | Gil & al. | Lovo & al. | PoWO |
| Trimezia | Trimezia | Trimezia | Trimezia | Trimezia |
| Trimezia | Neomarica | Neomarica | Neomarica | Trimezia |
| Pseudotrimezia | Pseudotrimezia | Pseudotrimezia | Pseudotrimezia | Trimezia |
| Pseudiris | Pseudiris | Trimezia | ||
| Deluciris | Trimezia |
Distinction between genera
When Trimezia was distinguished from Neomarica prior to molecular phylogenetic studies, i.e. entirely on morphological grounds, some vegetative characters were considered diagnostic. Trimezia in this sense always grows from corms, Neomarica almost always from rhizomes. Trimezia has flowering stems that are circular in cross-section, whereas Neomarica has flattened scapes. Lovo et al. consider these characteristics to be among those distinguishing their circumscription of Neomarica from the other genera into which they divide the tribe.Species
, Plants of the World Online accepted about 80 species of Trimezia. However, this includes species that other sources place in different genera in the tribe Trimezieae. The placement in Lovo et al., where given in their paper, is shown in the second column.| PoWO | Lovo et al. |
| Trimezia altivallis Ravenna – Brazil | Neomarica altivallis |
| Trimezia barretoi Christenh. & Byng – Brazil | Pseudotrimezia barretoi |
| Trimezia brachypus Ravenna – Brazil | Neomarica brachypus |
| Trimezia brevicaulis Ravenna – Brazil | Trimezia brevicaulis |
| Trimezia brevistaminea Christenh. & Byng – Brazil | Pseudotrimezia brevistaminea |
| Trimezia campanula Lovo & Mello-Silva – Brazil | Trimezia campanula |
| Trimezia candida Ravenna – SE. & S. Brazil to NE. Argentina | Neomarica candida |
| Trimezia capitellata Ravenna – Brazil | Trimezia capitellata |
| Trimezia castaneomaculata Christenh. & Byng – Brazil | Neomarica castaneomaculata |
| Trimezia cathartica Niederl. – Brazil | Pseudotrimezia cathartica |
| Trimezia caulosa Ravenna – Brazil | Trimezia caulosa |
| Trimezia chimantensis Steyerm. – S. Venezuela | Trimezia chimantensis |
| Trimezia cipoana Christenh. & Byng – Brazil | Pseudotrimezia sublateralis |
| Trimezia coerulea Ravenna – SE. & S. Brazil to Paraguay | Neomarica coerulea |
| Trimezia concava Christenh. & Byng – Brazil | Pseudotrimezia concava |
| Trimezia concolor Christenh. & Byng – Brazil | – |
| Trimezia datensis Christenh. & Byng – Brazil | – |
| Trimezia decora Ravenna – Brazil | Neomarica decora |
| Trimezia decumbens Ravenna – Brazil | Neomarica decumbens |
| Trimezia diamantinensis Christenh. – Brazil | Pseudotrimezia diamantinensis |
| Trimezia eburnea Christenh. & Byng – Brazil | Neomarica eburnea |
| Trimezia elegans Christenh. – Brazil | Pseudotrimezia elegans |
| Trimezia exillima Ravenna – Brazil | Trimezia exillima |
| Trimezia fistulosa R.C.Foster – Brazil | Pseudotrimezia fistulosa |
| Trimezia floscella Christenh. & Byng – Brazil | Neomarica floscella |
| Trimezia fosteriana Steyerm. – Venezuela | Trimezia fosteriana |
| Trimezia fulva Christenh. & Byng – Brazil | Pseudotrimezia fulva |
| Trimezia glauca Ravenna – SE. & S. Brazil | Neomarica glauca |
| Trimezia gracilis Christenh. & Byng – WC. & SE. Brazil to Paraguay | Neomarica gracilis |
| Trimezia guaricana Ravenna – Venezuela | – |
| Trimezia guianensis Ravenna – Guyana | – |
| Trimezia humilis Ravenna – Venezuela, SE. & S. Brazil | Neomarica humilis |
| Trimezia imbricata Christenh. & Byng – SE. Brazil | Neomarica imbricata |
| Trimezia involuta Christenh. & Byng – Brazil | Neomarica involuta |
| Trimezia itacambirae Christenh. & Byng – Brazil | – |
| Trimezia itamarajuensis Ravenna – Brazil | – |
| Trimezia itatiaica Ravenna – Brazil | Neomarica itatiaica |
| Trimezia jaguatirica Ravenna – Brazil | – |
| Trimezia juncifolia Benth. & Hook.f. – C. & S. Brazil | Pseudotrimezia juncifolia |
| Trimezia laevis Christenh. & Byng – Brazil | Pseudotrimezia pauli |
| Trimezia latifolia Ravenna – Brazil | Neomarica latifolia |
| Trimezia liebmannii Govaerts. – Brazil | – |
| Trimezia longifolia Christenh. & Byng – SE. Brazil | Neomarica longifolia |
| Trimezia martinicensis Herb. – C. America to Colombia, Lesser Antilles to Bolivia | Trimezia martinicensis |
| Trimezia mauroi Govaerts. – Brazil | Neomarica mauroi |
| Trimezia mogolensis Ravenna – Brazil | – |
| Trimezia monticola Christenh. & Byng – Brazil | – |
| Trimezia nana Christenh. & Byng – Brazil | Pseudotrimezia nana |
| Trimezia northiana Ravenna – Brazil | Neomarica northiana |
| Trimezia organensis Ravenna – Brazil | incertae sedis |
| Trimezia paradoxa Ravenna – Brazil | incertae sedis |
| Trimezia pardina Ravenna – Brazil | Neomarica pardina |
| Trimezia plicatifolia Chukr – Brazil | Pseudotrimezia plicatifolia |
| Trimezia portosecurensis Ravenna – Brazil | Neomarica portosecurensis |
| Trimezia pumila Christenh. & Byng – Brazil | Pseudotrimezia pumila |
| Trimezia pusilla Ravenna – Brazil | Pseudotrimezia pusilla |
| Trimezia recurvata Christenh. & Byng – Brazil | Pseudotrimezia recurvata |
| Trimezia rotundata Ravenna – Brazil | Trimezia rotundata |
| Trimezia rupestris Ravenna – Brazil | Deluciris rupestris |
| Trimezia sabini Ravenna – E. Brazil | Neomarica sabini |
| Trimezia sancti-vicentei Govaerts. – Brazil | Neomarica sancti-vicentei |
| Trimezia sergipensis Christenh. & Byng – Brazil | Neomarica sergipensis |
| Trimezia setacea Christenh. & Byng – Brazil | – |
| Trimezia silvestris Ravenna – SE. Brazil | Neomarica silvestris |
| Trimezia sobolifera Ravenna – Florida, Mexico, Venezuela | Trimezia sobolifera |
| Trimezia spathata Baker – Brazil to NE. Argentina | Trimezia spathata |
| Trimezia speciosa Christenh. & Byng – Brazil | Neomarica speciosa |
| Trimezia steyermarkii R.C.Foster – S. Mexico to NW. Venezuela | Trimezia steyermarkii |
| Trimezia striata Christenh. & Byng – Brazil | Pseudotrimezia striata |
| Trimezia synandra Christenh. & Byng – Brazil | Pseudotrimezia synandra |
| Trimezia tenuissima Christenh. & Byng – Brazil | Pseudotrimezia tenuissima |
| Trimezia truncata Ravenna – Brazil | Pseudotrimezia truncata |
| Trimezia unca Ravenna – Brazil | – |
| Trimezia variegata Ravenna – C. & S. Mexico to Panama | Neomarica variegata |
| Trimezia violacea Ravenna – Brazil | Deluciris violacea |
| Trimezia warmingii Christenh. & Byng – Brazil | – |
| Trimezia xyridea Christenh. & Byng – Brazil | Pseudotrimezia planifolia |