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.Kew World Checklist of Selected Plant Families 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 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 (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., pp. 375–379
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 "" ('without character'). The genus name is derived from the Greek words , , meaning 'three' and , , meaning 'greater', referring to the outer three tepals being much larger than the inner three. p. 505.
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 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 Neomarica Neomarica Neomarica Pseudotrimezia Pseudotrimezia Pseudotrimezia Pseudotrimezia Pseudiris Pseudiris Deluciris
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 , 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 altivallisTrimezia barretoi (R.C.Foster) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia barretoiTrimezia brachypus (Baker) Ravenna – Brazil (Bahia)Neomarica brachypusTrimezia brevicaulis Ravenna – Brazil (Bahia, Minas Gerais)Trimezia brevicaulisTrimezia brevistaminea (Chukr) Christenh. & Byng – Brazil (Minas Gerais: Serra do Cipó)Pseudotrimezia brevistamineaTrimezia campanula Lovo & Mello-Silva – Brazil (Minas Gerais)Trimezia campanulaTrimezia candida (Hassl.) Ravenna – SE. & S. Brazil to NE. ArgentinaNeomarica candidaTrimezia capitellata Ravenna – Brazil (Minas Gerais)Trimezia capitellataTrimezia castaneomaculata (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Bahia, Espírito Santo)Neomarica castaneomaculataTrimezia cathartica (Klatt) Niederl. – Brazil (Bahia, Minas Gerais, Goiás)Pseudotrimezia catharticaTrimezia caulosa Ravenna – Brazil (Bahia)Trimezia caulosaTrimezia chimantensis Steyerm. – S. Venezuela (Macizo del Chimantá)Trimezia chimantensisTrimezia cipoana (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia sublateralisTrimezia coerulea (G.Lodd.) Ravenna – SE. & S. Brazil to ParaguayNeomarica coeruleaTrimezia concava (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia concavaTrimezia concolor Christenh. & Byng – Brazil (Minas Gerais: Serra do Cipó)–Trimezia datensis (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)–Trimezia decora Ravenna – Brazil (São Paulo)Neomarica decoraTrimezia decumbens Ravenna – Brazil (São Paulo)Neomarica decumbensTrimezia diamantinensis (Ravenna) Christenh. – Brazil (Minas Gerais)Pseudotrimezia diamantinensisTrimezia eburnea (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Bahia)Neomarica eburneaTrimezia elegans (Ravenna) Christenh. – Brazil (Minas Gerais: Pico Itambé)Pseudotrimezia elegansTrimezia exillima Ravenna – Brazil (Minas Gerais)Trimezia exillimaTrimezia fistulosa R.C.Foster – Brazil (Minas Gerais: Serra do Cipó)Pseudotrimezia fistulosaTrimezia floscella (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Bahia)Neomarica floscellaTrimezia fosteriana Steyerm. – Venezuela (Bolívar)Trimezia fosterianaTrimezia fulva (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia fulvaTrimezia glauca (Seub. ex Klatt) Ravenna – SE. & S. BrazilNeomarica glaucaTrimezia gracilis (Herb.) Christenh. & Byng – WC. & SE. Brazil to ParaguayNeomarica gracilisTrimezia guaricana Ravenna – Venezuela (Guárico)–Trimezia guianensis Ravenna – Guyana–Trimezia humilis (Klatt) Ravenna – Venezuela, SE. & S. BrazilNeomarica humilisTrimezia imbricata (Hand.-Mazz.) Christenh. & Byng – SE. BrazilNeomarica imbricataTrimezia involuta (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Bahia, Espírito Santo)Neomarica involutaTrimezia itacambirae (Ravenna) Christenh. & Byng – Brazil (Minas Gerais: Serra do Alagoas)–Trimezia itamarajuensis Ravenna – Brazil (Bahia: Itamaraju)–Trimezia itatiaica Ravenna – Brazil (Rio de Janeiro)Neomarica itatiaicaTrimezia jaguatirica Ravenna – Brazil (Minas Gerais)–Trimezia juncifolia (Klatt) Benth. & Hook.f. – C. & S. BrazilPseudotrimezia juncifoliaTrimezia laevis (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia pauliTrimezia latifolia Ravenna – Brazil (Paraná)Neomarica latifoliaTrimezia liebmannii Govaerts. – Brazil (Rio de Janeiro to Paraná)–Trimezia longifolia (Link & Otto) Christenh. & Byng – SE. BrazilNeomarica longifoliaTrimezia martinicensis (Jacq.) Herb. – C. America to Colombia, Lesser Antilles to BoliviaTrimezia martinicensisTrimezia mauroi (A.Gil & M.C.E.Amaral) Govaerts. – Brazil (Rio de Janeiro)Neomarica mauroiTrimezia 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 nanaTrimezia northiana (Schneev.) Ravenna – Brazil (Espírito Santo to Paraná)Neomarica northianaTrimezia organensis Ravenna – Brazil (Rio de Janeiro)incertae sedisTrimezia paradoxa Ravenna – Brazil (Maranhão)incertae sedisTrimezia pardina Ravenna – Brazil (Minas Gerais, Rio de Janeiro)Neomarica pardinaTrimezia plicatifolia Chukr – Brazil (Minas Gerais: Serra do Cabral)Pseudotrimezia plicatifoliaTrimezia portosecurensis Ravenna – Brazil (Bahia)Neomarica portosecurensisTrimezia pumila (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia pumilaTrimezia pusilla Ravenna – Brazil (Goiás: Serra Dourada)Pseudotrimezia pusillaTrimezia recurvata (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia recurvataTrimezia rotundata Ravenna – Brazil (Paraná)Trimezia rotundataTrimezia rupestris Ravenna – Brazil (Minas Gerais)Deluciris rupestrisTrimezia sabini (Lindl.) Ravenna – E. BrazilNeomarica sabiniTrimezia sancti-vicentei (A.Gil & M.C.E.Amaral) Govaerts. – Brazil (São Paulo)Neomarica sancti-vicenteiTrimezia sergipensis (A.Gil & M.C.E.Amaral) Christenh. & Byng – Brazil (Sergipe)Neomarica sergipensisTrimezia setacea (Klatt) Christenh. & Byng – Brazil (Minas Gerais: Serra do Cipó)–Trimezia silvestris (Vell.) Ravenna – SE. BrazilNeomarica silvestrisTrimezia sobolifera Ravenna – Florida, Mexico (Veracruz, Oaxaca), VenezuelaTrimezia soboliferaTrimezia spathata (Klatt) Baker – Brazil to NE. ArgentinaTrimezia spathataTrimezia speciosa (Chukr & A.Gil) Christenh. & Byng – Brazil (Bahia)Neomarica speciosaTrimezia steyermarkii R.C.Foster – S. Mexico to NW. VenezuelaTrimezia steyermarkiiTrimezia striata (Lovo & Mello-Silva) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia striataTrimezia synandra (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia synandraTrimezia tenuissima (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia tenuissimaTrimezia truncata Ravenna – Brazil (Minas Gerais)Pseudotrimezia truncataTrimezia unca Ravenna – Brazil (Bahia)–Trimezia variegata (M.Martens & Galeotti) Ravenna – C. & S. Mexico to PanamaNeomarica variegataTrimezia violacea (Klatt) Ravenna – Brazil (Bahia, Minas Gerais)Deluciris violaceaTrimezia warmingii (Klatt) Christenh. & Byng – Brazil (Minas Gerais)–Trimezia xyridea (Ravenna) Christenh. & Byng – Brazil (Minas Gerais)Pseudotrimezia planifolia
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.
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