# 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 (e.g. for Trimezia gracilis, syn. Neomarica gracilis). 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 7 cm (2.8 in) in the case of T. pusilla to 1.6 m (5.2 ft) 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 (sepals) are larger than the inner ones (petals); both may have brown-purple markings at the base. The stamens have free filaments (i.e. they not fused together or fused to the style). 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" ('without character'). The genus name is derived from the Greek words tri, meaning "three", and meze, meaning "greater".
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 February 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 :
| Ravenna (2003) | Chukr & Giulietti (2008) | Gil & al. (2009) | Lovo & al. (2018) | PoWO (February 2025) |
| 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 (scapes) that are circular in cross-section, whereas Neomarica has flattened scapes. Lovo et al. (2018) consider these characteristics to be among those distinguishing their circumscription of Neomarica from the other genera into which they divide the tribe.

### Species

As of February 2025, 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. (2018), where given in their paper, is shown in the second column.
| PoWO (February 2025) | Lovo et al. (2018) |
| Trimezia altivallis Ravenna – Brazil (Espírito Santo) | Neomarica altivallis |
| Trimezia barretoi (R.C.Foster) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia barretoi |
| Trimezia brachypus (Baker) Ravenna – Brazil (Bahia) | Neomarica brachypus |
| Trimezia brevicaulis Ravenna – Brazil (Bahia, Minas Gerais) | Trimezia brevicaulis |
| Trimezia brevistaminea (Chukr) Christenh. & Byng – Brazil (Minas Gerais: Serra do Cipó) | Pseudotrimezia brevistaminea |
| Trimezia campanula Lovo & Mello-Silva – Brazil (Minas Gerais) | Trimezia campanula |
| Trimezia candida (Hassl.) Ravenna – SE. & S. Brazil to NE. Argentina | Neomarica candida |
| Trimezia capitellata Ravenna – Brazil (Minas Gerais) | Trimezia capitellata |
| Trimezia castaneomaculata (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Bahia, Espírito Santo) | Neomarica castaneomaculata |
| Trimezia cathartica (Klatt) Niederl. – Brazil (Bahia, Minas Gerais, Goiás) | Pseudotrimezia cathartica |
| Trimezia caulosa Ravenna – Brazil (Bahia) | Trimezia caulosa |
| Trimezia chimantensis Steyerm. – S. Venezuela (Macizo del Chimantá) | Trimezia chimantensis |
| Trimezia cipoana (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia sublateralis |
| Trimezia coerulea (G.Lodd.) Ravenna – SE. & S. Brazil to Paraguay | Neomarica coerulea |
| Trimezia concava (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia concava |
| Trimezia concolor Christenh. & Byng – Brazil (Minas Gerais: Serra do Cipó) | – |
| Trimezia datensis (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | – |
| Trimezia decora Ravenna – Brazil (São Paulo) | Neomarica decora |
| Trimezia decumbens Ravenna – Brazil (São Paulo) | Neomarica decumbens |
| Trimezia diamantinensis (Ravenna) Christenh. – Brazil (Minas Gerais) | Pseudotrimezia diamantinensis |
| Trimezia eburnea (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Bahia) | Neomarica eburnea |
| Trimezia elegans (Ravenna) Christenh. – Brazil (Minas Gerais: Pico Itambé) | Pseudotrimezia elegans |
| Trimezia exillima Ravenna – Brazil (Minas Gerais) | Trimezia exillima |
| Trimezia fistulosa R.C.Foster – Brazil (Minas Gerais: Serra do Cipó) | Pseudotrimezia fistulosa |
| Trimezia floscella (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Bahia) | Neomarica floscella |
| Trimezia fosteriana Steyerm. – Venezuela (Bolívar) | Trimezia fosteriana |
| Trimezia fulva (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia fulva |
| Trimezia glauca (Seub. ex Klatt) Ravenna – SE. & S. Brazil | Neomarica glauca |
| Trimezia gracilis (Herb.) Christenh. & Byng – WC. & SE. Brazil to Paraguay | Neomarica gracilis |
| Trimezia guaricana Ravenna – Venezuela (Guárico) | – |
| Trimezia guianensis Ravenna – Guyana | – |
| Trimezia humilis (Klatt) Ravenna – Venezuela, SE. & S. Brazil | Neomarica humilis |
| Trimezia imbricata (Hand.-Mazz.) Christenh. & Byng – SE. Brazil | Neomarica imbricata |
| Trimezia involuta (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Bahia, Espírito Santo) | Neomarica involuta |
| Trimezia itacambirae (Ravenna) Christenh. & Byng – Brazil (Minas Gerais: Serra do Alagoas) | – |
| Trimezia itamarajuensis Ravenna – Brazil (Bahia: Itamaraju) | – |
| Trimezia itatiaica Ravenna – Brazil (Rio de Janeiro) | Neomarica itatiaica |
| Trimezia jaguatirica Ravenna – Brazil (Minas Gerais) | – |
| Trimezia juncifolia (Klatt) Benth. & Hook.f. – C. & S. Brazil | Pseudotrimezia juncifolia |
| Trimezia laevis (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia pauli |
| Trimezia latifolia Ravenna – Brazil (Paraná) | Neomarica latifolia |
| Trimezia liebmannii Govaerts. – Brazil (Rio de Janeiro to Paraná) | – |
| Trimezia longifolia (Link & Otto) Christenh. & Byng – SE. Brazil | Neomarica longifolia |
| Trimezia martinicensis (Jacq.) Herb. – C. America to Colombia, Lesser Antilles to Bolivia | Trimezia martinicensis |
| Trimezia mauroi (A.Gil & M.C.E.Amaral) Govaerts. – Brazil (Rio de Janeiro) | Neomarica mauroi |
| Trimezia mogolensis Ravenna – Brazil (Minas Gerais) | – |
| Trimezia monticola (Klatt) Christenh. & Byng – Brazil (Minas Gerais: Pico do Itambé) | – |
| Trimezia nana (Lovo & Mello-Silva) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia nana |
| Trimezia northiana (Schneev.) Ravenna – Brazil (Espírito Santo to Paraná) | Neomarica northiana |
| Trimezia organensis Ravenna – Brazil (Rio de Janeiro) | incertae sedis |
| Trimezia paradoxa Ravenna – Brazil (Maranhão) | incertae sedis |
| Trimezia pardina Ravenna – Brazil (Minas Gerais, Rio de Janeiro) | Neomarica pardina |
| Trimezia plicatifolia Chukr – Brazil (Minas Gerais: Serra do Cabral) | Pseudotrimezia plicatifolia |
| Trimezia portosecurensis Ravenna – Brazil (Bahia) | Neomarica portosecurensis |
| Trimezia pumila (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia pumila |
| Trimezia pusilla Ravenna – Brazil (Goiás: Serra Dourada) | Pseudotrimezia pusilla |
| Trimezia recurvata (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia recurvata |
| Trimezia rotundata Ravenna – Brazil (Paraná) | Trimezia rotundata |
| Trimezia rupestris Ravenna – Brazil (Minas Gerais) | Deluciris rupestris |
| Trimezia sabini (Lindl.) Ravenna – E. Brazil | Neomarica sabini |
| Trimezia sancti-vicentei (A.Gil & M.C.E.Amaral) Govaerts. – Brazil (São Paulo) | Neomarica sancti-vicentei |
| Trimezia sergipensis (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Sergipe) | Neomarica sergipensis |
| Trimezia setacea (Klatt) Christenh. & Byng – Brazil (Minas Gerais: Serra do Cipó) | – |
| Trimezia silvestris (Vell.) Ravenna – SE. Brazil | Neomarica silvestris |
| Trimezia sobolifera Ravenna – Florida, Mexico (Veracruz, Oaxaca), Venezuela | Trimezia sobolifera |
| Trimezia spathata (Klatt) Baker – Brazil to NE. Argentina | Trimezia spathata |
| Trimezia speciosa (Chukr & A.Gil) Christenh. & Byng – Brazil (Bahia) | Neomarica speciosa |
| Trimezia steyermarkii R.C.Foster – S. Mexico to NW. Venezuela | Trimezia steyermarkii |
| Trimezia striata (Lovo & Mello-Silva) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia striata |
| Trimezia synandra (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia synandra |
| Trimezia tenuissima (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia tenuissima |
| Trimezia truncata Ravenna – Brazil (Minas Gerais) | Pseudotrimezia truncata |
| Trimezia unca Ravenna – Brazil (Bahia) | – |
| Trimezia variegata (M.Martens & Galeotti) Ravenna – C. & S. Mexico to Panama | Neomarica variegata |
| Trimezia violacea (Klatt) Ravenna – Brazil (Bahia, Minas Gerais) | Deluciris violacea |
| Trimezia warmingii (Klatt) Christenh. & Byng – Brazil (Minas Gerais) | – |
| Trimezia xyridea (Ravenna) Christenh. & Byng – Brazil (Minas Gerais) | Pseudotrimezia planifolia |
* Trimezia candida (syn. Neomarica candida)
* T. coerulea (syn. Neomarica coerulea)
* T. fosteriana
* Flower of T. juncifolia (syn. Pseudotrimezia juncifolia)
* Flower of T. martinicensis, naturalized in Malaysia
* Flower of Trimezia violaceae (syn. Deluciris violacea) in Goiás, Brazil

## Distribution and habitat

The genus is native to the warmer parts of southern Mexico, Central America, South America, Florida, and parts of the West Indies. Trimezia species typically grow in damp grassland.