Apostle Plant

''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
/ref> ''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.

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.

File:Lily flower.jpg, ''Trimezia candida'' (syn. ''Neomarica candida'')
File:Gardenology.org-IMG 9843 rbgm10dec.jpg, '' T. coerulea'' (syn. ''Neomarica coerulea'')
File:Trimezia fosteriana flower.JPG, '' T. fosteriana''
File:Trimezia juncifolia.jpg, Flower of '' T. juncifolia'' (syn. ''Pseudotrimezia juncifolia'')
File:Trimezia martinicensis.jpg, Flower of '' T. martinicensis'', naturalized in Malaysia
File:Trimezia violacea flower.jpg, 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.

References

{{Taxonbar, from1=Q2709295, from2=Q65041036, from3=Q1955537, from4=Q17412808, from5=Q7255671

Iridaceae genera
Taxa named by William Herbert (botanist)
Flora of the Neotropical realm