Zanonia bibracteata Cramer, nom. superfl. (= Tradescantia zanonia (L.) Sw.).

See Pellegrini (2017).

Tradescantia subg. Campelia is the most widespread subgenus, extending from Mexico through Central America, the Antilles, and South America. In South America, it is distributed along the Andes, extending into the Amazon Forest and Atlantic Forest biomes, but skipping most of the South American seasonal biomes (e.g. the Caatinga, Cerrado, Chaco, Pampa, and Pantanal biomes; Fig. 1). The overall distribution of T. subg. Campelia recognised in the present study differs slightly from the one presented by Pellegrini (2017). This more accurate distribution results from the exclusion of dubious, cultivated, and invasive species records, made possible only by our ongoing and meticulous investigations of the horticulturally important species T. spathacea, T. zanonia, and T. zebrina.

Figure 1. 

Distribution map for Tradescantia subg. Campelia. Purple – Tradescantia sect. Campelia; White dots – Tradescantia sect. Corinna; Hatched purple – Tradescantia sect. Cymbispatha; Lilac – Tradescantia sect. Rhoeo.

Out of the four recognised sections, T. sect. Rhoeo is the most narrowly distributed one, with T. sect. Corinna being mostly Mesoamerican (but reaching southern Mexico), and T. sect. Cymbispatha extending from Mexico to Central America and the Andean region of South America. Finally, T. sect. Campelia is the most widely distributed section, with its distribution corresponding to that of the entire subgenus.

Due to the estimated species richness (ca 30 species; Marco Pellegrini pers. obs.) and known morphological variation within Tradescantia subg. Campelia, we propose its subdivision into four sections: 1) T. sect. Campelia; 2) T. sect. Corinna; 3) T. sect. Cymbispatha; and 4) T. sect. Rhoeo. This facilitates systematic efforts within this taxonomically complex and morphologically diverse group (Pellegrini 2017), which also includes the most commonly cultivated species in the genus.

Tradescantia sect. Corinna, T. sect. Cymbispatha, and T. sect. Rhoeo match the circumscription proposed by Hunt (1986a), while T. sect. Campelia is expanded to include T. sect. Zebrina sensu Hunt (1986a). To facilitate their characterisation and recognition, we provide an identification key to the sections of T. subg. Campelia. Detailed descriptions, comments, maps, illustrations, and further taxonomic updates will be provided for each section in their respective taxonomic accounts (Pellegrini et al. in prep.). This is made necessary due to the convoluted taxonomic and nomenclatural history of these sections and the included taxa.

Tradescantia discolor L’Hér. (= T. spathacea Sw.).

Herbs chamaephytes, robust, bromelioid to dracaenoid rosettes, solitary to clump-forming, monopodial, perennial, succulent, terrestrial, rupicolous or epiphytic, base definite; glandular microhairs with basal cell with a short neck, ca as wide as long, medial cell barrel-shaped, ca as wide as long, apex slightly wider than base, apical cell widely ellipsoid to obovoid, ca as wide as long, ca as wide as to slightly wider than the medial cell, apex acute, macrohairs absent (except for staminal moniliform hairs). Roots thin, fibrous. Stems ascending to erect, base becoming prostrate in older individuals, robust, succulent, unbranched, sometimes branched at base, rarely branching elsewhere due to damage to the apical bud, rooting at base or the nodes touching the substrate; internodes inconspicuous to elongate, becoming distally shorter, glabrous. Leaves spirally-alternate or pseudoverticillate, congested at the apex of the stem, sessile, glaucous when young, especially abaxially; sheaths succulent, slightly flaccid, glabrous, sometimes marcescent along the stems; ptyxis convolute; blades loriform to linear-lanceolate to narrowly lanceolate, slightly narrowed to constricted towards the base (but not forming a pseudopetiole), flat or conduplicate to canulate, succulent, cartilaginous, especially along the margin, glabrous on both sides, base symmetric, cuneate to truncate, margin flat, glabrous, apex acute to acuminate; midvein conspicuous or not, secondary veins inconspicuous, becoming more evident on both sides when dry. Synflorescences composed of a solitary main florescence or a main florescence and 1–3 coflorescences, axillary; synflorescence stems short, internodes short, glabrous; synflorescence leaves (peduncle bracts) present or not, if present bracteose. Inflorescences consisting of a shortly-pedunculate to pedunculate main florescence, internally mucilaginous; basal bract inconspicuous, tubular, hyaline, glabrous; peduncle glabrous; supernumerary bracts sometimes present, sheath absent; main axis inconspicuous; cincinnus bracts equal to unequal to each other, spathaceous, free, overlapping or not, conduplicate, straight to falcate, glabrous on both sides, base saccate or not, margin glabrous; cincinni 2, sessile, contracted, opposite, fused back-to-back into a double-cincinni, double-cincinni many-flowered; bracteoles spathaceous, enclosing the cincinnus, membranous, hyaline, glabrous. Flowers bisexual, slightly zygomorphic due to the unequal sepals, flat; floral buds oblongoid, glabrous, apex acute; pedicels succulent to spongy, glabrous, apically not gibbous, recurved at pre- and post-anthesis, erect to gently recurved at anthesis; sepals 3, free, subequal, the dorsal one slightly larger than the lateral ones, navicular, membranous or chartaceous, dorsally keeled or not, hyaline to semi-opaque, white to light green, glabrous, base obtuse to cuneate, margin entire, hyaline, apex acute, cucullate or not, becoming marcescent in fruit; petals 3, equal, free, sessile, flat, white, base obtuse, margin entire to minutely and unevenly lacerate, apex acute to obtuse; stamens 6, in two whorls, subequal, the outer whorl shorter than the inner one, filaments free from the petals and each other, straight at anthesis and post-anthesis, white, bearded on the lower 1/2 with moniliform hairs, hairs shorter than 1/2 the length of the filament, white, anthers basifixed, connective obdeltoid, apex truncate to slightly emarginate, anther sacs elliptic, divergent, pollen white to cream-coloured in vivo; ovary sessile, widely oblongoid to subglobose, white, smooth, glabrous, 3-locular, locules equal, 1-ovulate, ovules uniseriate, style cylindrical throughout, straight, white, stigma truncate, pistil shorter than the stamens. Capsules dehiscent, 3-valved, oblongoid to widely oblongoid to subglobose, smooth, glabrous, apex apiculate due to the persistent style base. Seeds (0–)1 per locule, narrowly oblong to oblong to oblong-elliptic, cleft towards the embryotega, ventrally flattened, exarillate, farinose, farinae white, testa divided into two regions (an outer rim and a large central region around the embryotega); embryotega semilateral, conspicuous, without a prominent apicule, apex obtuse, gently curved towards the cleft; hilum linear to gently curved, inside a deep and narrow groove.

Pollen grains released as monads, medium-sized (P - 17.4–45.4 × E - 24.4–53.3 µm), heteropolar, oblate, outline elliptic in polar view, outline flattened-convex or biconvex in equatorial view, dry pollen boat-shaped. Aperture 1-sulcate, anasulcate; sulcus long and broad (26.7–56.4 × 12.1–22.9 µm), 1/4 to 1/3 of the total grain surface, non-operculate, sunken when dry, membrane nanogranulate-granulate or verrucate-granulate, with perforations on the foot of the sculptural elements. Sexine ultrasculpture densely microverrucate-perforate, sparsely rugulate or rugulate-fossulate, elements reduced and more closely together in the transitional zone. Exine 1–1.5 µm thick, internally striate-rugulate; tectum tectate-perforate to semitectate, insulate, undulate (Fig. 2).

Figure 2. 

Pollen morphology of Tradescantia sect. Rhoeo. A–C. Tradescantia concolor. A. General view showing the flattened-convex form, equatorial view. B. General view showing the large and broad sulcus and the microverrucate-perforate, sparsely rugulate elements, polar view. C. Detail of the verrucate-granulate and sparse nanogranulate elements. D–F. Tradescantia spathacea. D. General view showing the biconvex form, equatorial view. E. General view showing two pollen grains with a large and broad sulcus and the microverrucate-perforate sexine presenting sparsely rugulate-fossulate elements, polar view (top), oblique polar view (bottom). F. Detail of the nanogranulate-granulate membrane. Scale bars: A, B, D, E = 10 µm; C, F = 1 µm. Photographs A–C by Heidemarie Hallbritter, D–F by Amra Brkic.

Tradescantia sect. Rhoeo is naturally found only on the Yucatán Peninsula (Mexico) and surrounding areas, including Belize and Guatemala (Figs 1, 4). It is cultivated elsewhere around the globe, where it has sometimes become naturalised.

Tradescantia sect. Rhoeo is found in lowland to submontane seasonally dry forests and rainforests. Plants are terrestrial or rupicolous, but can also be commonly found growing as epiphytes (especially T. spathacea).

Tradescantia sect. Rhoeo is widely cultivated around the globe, especially in tropical regions. Out of the two recognised species, T. spathacea has sometimes become naturalised outside its native range (e.g. the West Indies, the Antilles, and Central America). However, they generally do not seem to act as aggressive and invasive weeds, unlike other species of Tradescantia (e.g. T. fluminensis Vell. and T. zebrina). The only exception appears to be T. spathacea in Australia and Florida, USA, where it is a well-established and aggressive garden escapee.

Horticulturally very important, being cultivated as an ornamental around the world, typically grown as an outdoor groundcover or as a houseplant in temperate climates. Tradescantia spathacea is one of the longest-cultivated species outside of T. subg. Tradescantia, and a number of cultivars have been selected for their unusual variegated foliage and/or compact size. The variegation in T. sect. Rhoeo is typically caused by chimeral albino mutations (Tradescantia.uk 2025), rather than virus infections, as initially hypothesised by Pellegrini (2017). Mutations which occur in the shoot apical meristem are reproduced and maintained as the cells divide. When a mutation causes albino cells due to a reduction or absence of chlorophyll, the chimeral mixture of mutated and normal cells in the meristem produces a visible variegated pattern in the growing leaves (Frank and Chitwood 2016). Such mutations reduce the vigour of the plant, but are often selected for ornamental horticulture. Mericlinal or marginal chimaeras have separate layers of genetically distinct cells in the meristem, which result in leaves with a consistent pattern of one colour near the margin and another colour at the base and centre. Periclinal or sectoral chimaeras have a mixture of cells within one or more meristem layers, resulting in highly variable stripes or streaks (Tradescantia.uk 2025). In addition to albino cells, non-photosynthetic pigments can produce further colour variations, which may be selected genetically or vary according to environmental conditions (Pellegrini 2017; Tradescantia.uk 2025).

The leaves of T. spathacea are cooked to extract a purple dye, which the Mayans used to colour fabrics and cosmetics (Standley and Steyermark 1952). Tradescantia spathacea (and possibly also T. concolor) is used in Mexico for the treatment of sores and wounds, as well as for its antiseptic and anti-inflammatory properties. Further traditional uses include (Prajapati et al. 2020; Butnariu et al. 2022): 1) preparations made using the whole plant as insecticide, to treat wounds, cough, and to loosen mucus; 2) root preparations to treat cold, sore throat, whooping cough, and nasal bleeding; 3) stem preparations to treat hematemesis; 4) leaf preparations to treat burn wounds, psoriasis, grazes, cough, cold, sore throat, whooping cough, nasal bleeding, asthma, dysentery, haemoptysis, tuberculosis, kidney infections, haematuria, diarrhoea, entrorrhagia, hypoglycaemia, snakebites, anxiety and depression, and as an anticonceptional; and 5) flower preparations to treat cough, fever, and bronchitis. Medical trials have also demonstrated significant medicinal potential for T. spathacea in the treatment of AIDS, breast cancer, lymphocyte stimulation, tuberculosis, and as a potent antibacterial, antiviral agent, and antioxidant (Prajapati et al. 2020; Butnariu et al. 2022).

Species in this section are commonly known worldwide as Boat-lily, cradle-lily, Moses-in-the-cradle, oyster-lily, and oyster plant (English), and as Adam en Eva, barco-de-Moises, cordobán, hierba-del-cáncer, maguey blanco, magueyito blanco, niñas embarcadas, planta-de-hígado, señoritas embarcadas (Spanish). In Belize, it is known as es’chiu. In Mexico, they are known by a series of names, depending on the region and language. They are known in Mayan as chactasam / chak tsam / chak-ts’am / chactsan / chaktasan, matlali, yaxtsam / yastsana / yaxtsana / yaxtsanah / ya’axts’ana’, ta’ak / ya’ak, ts’am (country, Campeche, Quintana Roo, Tabasco, Veracruz, and Yucatán); ej pets’ (Campeche, Quintana Roo, and Yucatán); and eek’pets and chac tzab (Yucatán). In Mixe, they are known as tsa’am (country, Campeche, Tabasco, Veracruz, and Yucatán). Finally, in Mexican Spanish, they are known as hierba del cáncer, maguey, zopilotera (country), and roeo (Campeche, Quintana Roo, and Yucatán).

From the Romanised “Rhoiṓ” of the Ancient Greek “Ῥοιώ”, derived from the Greek “ῥείω” (rheíō, meaning “to flow” or “stream”). The name might refer to two distinct female characters from Greek mythology: 1) the daughter of the Argonaut hero Staphylus (son of the wine-god Dionysus), lover of the Olympian god Apollo, and mother of Anius (Smith 1873: 178); or 2) a Trojan naiad daughter (also known as Strymo, from the Romanised “Strȳmōn” of the Ancient Greek “Στρυμών”, meaning “stream” or “river”) of the river god Scamander, wife of King Laomedon of Troy, and mother of Tithonus (Smith 1873: 390; Dindorf 1875: 154, 369). Both characters have names associated with rivers and streams, although for different reasons. However, Hance (1852: 659) provides no etymology for his name, let alone which of the two Rhoeo he might be referring to.

Nonetheless, based on the Greek mythos, it is much more likely that the name refers to the first Rhoeo. According to legend (Smith 1873: 178), when Staphylus discovered Rhoeo’s pregnancy, he believed his daughter had become pregnant by a regular man, rather than a god. Taken by rage, he placed her inside a chest and cast her out to sea. Rhoeo ended up landing on the island of Delos, which Apollo protected. It would make sense that Hance (1852) intended to make a parallel between the boat-shaped inflorescence of T. spathacea and the chest in which Rhoeo was placed. Interestingly, a similar motif can be observed in most vernacular names for members of this group (e.g. boat-lily, cradle-lily, Moses-in-the-cradle, etc.).

Tradescantia sect. Rhoeo has pollen of the Tradescantia type (i.e. Type 3 sensu Poole and Hunt 1980). Poole and Hunt (1980) studied both species recognised by us as different cultivars or varieties of Rhoeo spathacea (Sw.) Stearn (ranks applied inconsistently in their study). These authors included both species in their pollen Type 3, based on the size of their pollen grains (P - 15–45 × E - 26–62 µm), “cerebroid” exine ornamentation (i.e. microverrucate-perforate sensu Halbritter et al. 2018), insulate tectum, coarsely granulate sulcal membrane, and thinner exine (1–1.5 µm thick). Nonetheless, the sulcal membrane of T. sect. Rhoeo is recorded by us as nanogranulate-granulate or verrucate-granulate, with this difference being species-specific. Poole and Hunt (1980) also highlighted the difference in polar and equatorial axis length between both species, with T. spathacea (either as R. spathacea var. spathacea or R. spathacea ‘Discolor’) having smaller pollen grains when compared to T. concolor (either as R. spathacea var. concolor or R. spathacea ‘Concolor’).

Tradescantia sect. Rhoeo has a basic chromosome number of x = 6 (Sax 1931; Jones and Jopling 1972; Hunt 1986a; Pellegrini 2017). The complement is symmetric, consisting of metacentric and submetacentric chromosomes, which are smaller than the x = 6 chromosomes of T. subg. Mandonia, T. subg. Setcreasea, and T. subg. Tradescantia (Jones and Jopling 1972; Hunt 1986a; Pellegrini 2017). The basic chromosome number x = 6 is one of the synapomorphies supporting the clade comprising T. subg. Campelia, T. subg. Mandonia, T. subg. Setcreasea, and T. subg. Tradescantia (Pellegrini 2017).

Rhoeo was described based on Tradescantia discolor (= T. spathacea) and was recognised as a monospecific genus for almost 100 years (Hunt 1986a). The genus was proposed solely based on its 1-ovulate locules, but was most widely recognised for its succulent and bromelioid habit. However, it shares with Tradescantia the double-cincinni fused back-to-back and subtended by frondose bracts, each individual cincinnus sessile and contracted, the Tradescantia-type flower, the Tradescantia-type pollen, seeds with a linear hilum, and the basic chromosome number of x = 6 (Hunt 1986a; Pellegrini 2017). Based on these morphological similarities, Hunt (1986a) reduced Rhoeo to a section in Tradescantia.

Tradescantia sect. Rhoeo is very distinctive and easily differentiated from T. sect. Campelia, T. sect. Corinna, and T. sect. Cymbispatha due to its bromelioid to dracaenoid habit, monopodial growth, glandular microhairs with cells as wide as long, lack of macrohairs on the vegetative organs and most reproductive ones (except for the staminal hairs), robust stems, convolute ptyxis, very succulent leaves, axillary clustered synflorescences, connectives obdeltoid, and its elliptic anther sacs. It shares with T. sect. Campelia a well-developed hypodermis on both sides of the leaf-blade, with T. sect. Corinna its spathaceous bracteoles, and with T. sect. Cymbispatha its flat flowers.

[Illustration] Original illustration by Walter Hood Fitch at the Illustration section of the Royal Botanic Gardens, Kew’s Library and Archives, later published in Baker (1868: t. 48); lectotype (designated here).

Herbs 10–120 m tall, 20–90 cm diam., bromelioid to dracaenoid rosettes. Stems ascending to erect, rooting at base; internodes 0.1–9.7 cm long, a very long internode followed by many inconspicuous to very short ones (causing the pseudoverticillate phyllotaxy), light green to green. Leaves pseudoverticillate; sheaths 0.8–1.9 cm long, light green to light silvery-green; blades 17.5–40 × 1.6–5.5 cm, ascending to patent, generally the larger leaves becoming deflexed with age, adaxially light green to green, abaxially light green to light silvery-green, rarely olive-green, margin light green to yellowish-green to vinaceous; midvein conspicuous or not, adaxially canaliculate, becoming inconspicuous on the upper third, abaxially inconspicuous, secondary veins 3–4 pairs, inconspicuous, becoming more evident on both sides when dry. Synflorescences composed of a solitary main florescence, rarely a main florescence and 1–2(–many) coflorescences; synflorescence internodes 0.6–4.9 cm long, cream-coloured to light green; synflorescence leaves (peduncle bracts) present or not, when present frondose to bracteose, sometimes reduced to a bladeless sheath, chartaceous to cartilaginous (frondose to bracteose) or membranous (bladeless sheath), adaxially cream-coloured to light green, abaxially cream-coloured to light green to green. Inflorescences with peduncle 1.9–3.4 cm long, light green; supernumerary bracts sometimes present, when present equal to subequal to the cincinnus bracts; cincinnus bracts 2.2–5.3 × 2.5–5.1 cm, equal to each other, trullate to widely trullate to very widely trullate, concave to navicular, overlapping or not, adaxially light green, becoming white to cream-coloured at base, light green to green along the veins and margin, abaxially green to silvery-green, becoming cream-coloured to light green to light silvery-green at base, green along the veins and margin, margin rarely speckled with pink to vinaceous, base cuneate to obtuse, saccate, apex acuminate to cuspidate, secondary veins 3–8 pairs; double-cincinni 30–50-flowered; bracteoles with base sometimes suffused with light green. Flowers with floral buds 5.3–5.8 × 3–3.5 mm, white to light green; pedicels 1.5–1.8 cm long, white to light green; sepals 4.5–6.5 × 2.5–3.5 mm, elliptic to widely elliptic to widely ovate, chartaceous, dorsally keeled, semi-opaque, white to light green, apex acute, cucullate; petals 6.5–8 × 6.5–7 mm, widely ovate to very widely ovate; stamens with filaments 6.7–8.8 mm long, anthers 0.8–1 × 0.9–1.3 mm, connective cream-coloured to pale yellow, anther sacs cream-coloured to pale pink to brownish-pink; ovary 1.9–2.5 × 1.5–2.2 mm, style 2.7–3.9 mm long. Capsules 3.8–5.2 × 2.7–4.9 mm, widely oblongoid to subglobose, when immature light green to green, becoming greenish-brown to tan-coloured when mature. Seeds 2.9–4.5 × 1.6–2.3 mm, oblong to oblong-elliptic, densely farinose, outer rim scrobiculate, ridges radiating from the embryotega, central testa smooth or almost so.

Pollen biconvex in equatorial view. Axis P - 21 (24.1 ± 0.3) 27 × E - 39.2 (45.2 ± 0.5) 53.3 µm. Sulcus 39.5 (45.4 ± 0.7) 56.4 × 12.1 (15.8 ± 0.5) 22.9 µm, membrane nanogranulate-granulate. Sexine ultrasculpture microverrucate-perforate, sparsely rugulate-fossulate. Exine 1 (1.4 ± 0.1) 1.5 µm thick; tectum tectate-perforate to semitectate (Fig. 2A–C).

Tradescantia concolor is restricted to the Yucatán Peninsula and surrounding areas, occurring in Belize, Guatemala, and Mexico (Campeche, Chiapas, Tabasco, Quintana Roo, and Yucatán) (Fig. 4).

Tradescantia concolor can be found growing from 20 to 600 m a.s.l. in lowland to lower montane rainforests and seasonally dry forests, as terrestrial or rupicolous, more rarely as an epiphyte.

Tradescantia concolor flowers and fruits profusely throughout the year if conditions are suitable, especially in cultivation. In the wild, it is most frequently found in bloom and fruit from September to March. It flowers commonly in cultivation, including as an indoor container plant, without any apparent requirement for seasonal or environmental triggers. It is self-compatible, readily producing viable seeds even when isolated (Avery Rowe pers. obs.).

Commonly known in Mexico (Spanish) as maguey blanco and maguey verde (Campeche, Quintana Roo, and Yucatán).

Derives from the combination of the Latin prefix “con-” (indicating “completeness”) + “color”, in reference to its completely green leaves.

Tradescantia concolor possesses a wide EOO (ca 211,075 km²) and AOO (ca 392 km²). It is still consistently observed in the wild, forming medium- to large-sized subpopulations. Thus, following the IUCN (2012) criteria and the IUCN Standards and Petitions Committee (2024) recommendations, we suggest that it be considered Least Concern (LC, criterion B).

Figure 3. 

Tradescantia concolor. A. Habit showing the erect and elongated stems, and pseudo-verticillate leaves. B. Detail of the stem showing the pseudo-verticillate phyllotaxy and axillary inflorescences. C. Detail of the leaf sheaths. D. Detail of the adaxial side of the leaf blade showing the characteristic dark green colouration with yellowish-green margin. E. Detail of the abaxial side of the leaf blade showing the characteristic green colouration. F. Detail of the inflorescence showing the non-overlapping cincinnus bracts with a saccate base and an immature fruit exserted from the bracts. G. Front view of a flower showing the membranous sepals. H. Detail of the anther showing the obdeltoid yellow connective and red to maroon anther sacs. I. Detail of the style showing the truncate stigma. J. Immature capsule with a mature seed showing the seed’s oblong outline, semi-lateral embryotega, and linear hilum slightly shorter than the seed. Photographs A–B, E by Philip K. Nelson; C–D, J by Avery Rowe; F, H–I by Jim Conrad.

MEXICO – Campeche • Hopelchen, 5 km S of centre of Hopelchen along road to Dzibalchen; 30 Dec. 1985; fl., fr.; M. Nee 32389; NY, US, XAL. – Chiapas • Ocosingo, Nuevo Guerrero; 11 Apr. 2002; fl.; G. Aguilar M. 490; MEXU. – Quintana Roo • Felipe Carillo, Puerto, Lag. Chichankanab; 26 Mar. 1984; fl.; J.J. Ortiz 478; CICY, MEXU, XAL. – Tabasco • Tenosique, 10 km de Tenosique, a 100 m de la antena; 19 Feb. 1983; fl.; Zamudio et al. 259; CASAT, MEXU. – Veracruz • Soteapan, San Fernando; 16 Oct. 1999; fl.; M. Leonti 90; MEXU. – Yucatán • Tekax, Cueva de Akil, 8 km al O de Akil, enfrente de la bomba de riego; 3 Aug. 1997; fl.; G. Ibarra-Manríquez et al. 4133; MEXU.

BELIZE – Belize • Gracie Rock, 1.5 miles S of Mile 22 on Western Highway; 4–5 Jun. 1973; fl., fr.; T.B. Croat 23833; MO, US. – Cayo • Line Transect 1, West of Hummingbird Highway, 7 miles S of junction with Western Highway; 8 Aug. 1970; fl., fr.; D.L. Spellman & W.W. Newey 1977; MO. – Corozal • s.loc.; 1931–1932; fl., fr.; P.H. Gentle 355; F, US. – Orange Walk • Honey Camp; Nov. 1928; fl., fr.; C.L. Lundell 102; K, US. – Stann Creek • Humming Bird Highway, high ridge, base of hill, Humming Bird Gap; 15 Aug. 1956; fl., fr.; P.H. Gentle 9215; F, K. – Toledo • Las Sierritas, 20 km west of Big Creek Settlement, eastern slopes of Cerrito, the tallest hill in Las Sierritas; 4 Dec. 1997; fl., fr.; T. Hawkins 1617; MEXU, MO, US, VRJ.

GUATEMALA – El Petén • San José, NW shore of Lake Petén Itzá, between Nuevo San José and La Providencia/Trinidad; 15 Dec. 1994; fl., fr.; B. Wallnöfer 9617; MO, W, U.

Tradescantia concolor was initially deemed to only represent a variation in leaf colouration of T. spathacea. However, in addition to the morphological differences highlighted in the key, both species also differ in their distribution and ecological preferences (Fig. 4). Pollen morphology also differs between both species, with T. concolor having larger [P - 21 (24.1 ± 0.3) 27 × E - 39.2 (45.2 ± 0.5) 53.3 µm] and biconvex grains, smaller sulcus [39.5 (45.4 ± 0.7) 56.4 × 12.1 (15.8 ± 0.5) 22.9 µm], different membrane ornamentation (nanogranulate-granulate), sexine with distinct ornamentation (microverrucate-perforate, sparsely rugulate-fossulate), and generally thicker exine [1 (1.4 ± 0.1) 1.5 µm]. Finally, despite being partially sympatric with T. spathacea and exhibiting overlap in phenology, no naturally occurring intermediate specimens have been observed or reported, which suggests that they do not hybridise. This further supports the recognition of two distinct entities.

Tradescantia concolor has historically been recognised as either a variety, a form, or, in the past 40 years, as a cultivar (i.e. Tradescantia spathacea ‘Concolor’). Cultivated specimens are generally unnamed wild forms. The species’ characteristic growth form and phyllotaxy may not be evident in cultivation, especially when plants are grown in smaller pots or plots, due to pruning long or leafless stems.

Figure 4. 

Distribution map for Tradescantia sect. Rhoeo. Green – Tropical and Subtropical Moist Broadleaf Forests; Pale Yellow – Tropical and Subtropical Dry Broadleaf Forests; Brown – Tropical and Subtropical Coniferous Forests; Red – Deserts and Xeric Shrublands; Teal – Mangroves and Coastal Environments.

Figure 5. 

Tradescantia spathacea. A. Habit, showing the erect and elongated stem, and plantlets at the base of the mother plant. B. Detail of the stem showing the marcescent leaf sheaths and secondary roots. C. Detail of the stem showing the spirally-alternate phyllotaxy with leaves congested at the apex of the stem. D. Detail of the adaxial side of the leaf blade showing the characteristic dark green colouration with vinaceous margin. E. Detail of the abaxial side of the leaf blade showing the characteristic vinaceous colouration. F. Inflorescence showing the presence of one supernumerary bract and overlapping cincinnus bracts with non-saccate base. G. Detail of the inflorescence with partially removed cincinnus bracts showing the spathaceous and membranous bracteoles and flower buds, flowers, and fruits in various stages of development. H. Front view of a flower showing the membranous sepals. I. Detail of the anther showing the obdeltoid yellow connective and red to maroon anther sacs. J. Detail of the style showing the truncate stigma. K. Immature capsule with a mature seed showing the seed’s narrowly elliptic outline, semi-lateral embryotega, and linear hilum as long as the seed. Photographs by Marco O.O. Pellegrini.

Cultivation requirements are flexible, and a range of soil types, light levels, and temperatures is tolerated. Container-grown specimens are susceptible to rot from excess moisture but are highly tolerant of drought. Growth is rapid, and propagation is easily achieved through stem cuttings, which also results in the production of numerous plantlets below the cut.

Leaves adaxially light green to green to olive-green, variegated with yellow stripes, abaxially olive-green.

Cultivar of unknown origin, most likely lost from cultivation, as it has not been documented since it was first described.

The Latin name would not be commonly considered valid following the ICNCP (Brickell et al. 2016). However, it is accepted by an ICRA decision as the plant has not been given any other names.

MEXICO – Campeche • San Francisco de Campeche, cultivated at the West Indies (most likely Jamaica); 1784–1786; fl.; O.P. Swartz s.n.; lectotype (designated here): S [S-R-6172!]; isolectotype: S [S07-10830!].

Herbs 10–60 cm tall, 10–70 cm diam., bromelioid rosettes. Stems ascending to erect, base becoming prostrate in older individuals, rooting at base or the nodes touching the substrate; internodes 0.2–3.1 cm long, distally shorter, light green to green to dark green or vinaceous to purple. Leaves spirally-alternate; sheaths (1–)1.6–3.4 cm long, green to cream-coloured to pink to purplish-pink becoming vinaceous to purple towards the apex; blades 15.3–35.2 × 2.4–6.8 cm, ascending to patent, adaxially dark bluish-green to greyish-green to dark green to green, abaxially vinaceous to purple, margin vinaceous to purple; midvein slightly conspicuous to conspicuous, adaxially impressed to canaliculate, becoming slightly prominent on the upper third, abaxially slightly prominent, round, secondary veins 3–5 pairs, inconspicuous, becoming more evident on both sides when dry. Synflorescences composed of a solitary main florescence or a main florescence and 1–4(–many) coflorescences; synflorescence internodes 0.6–3.9 cm long, light green to cream-coloured to purplish-pink; synflorescence leaves (peduncle bracts) present, bracteose or reduced to a bladeless sheath, chartaceous, adaxially cream-coloured to light green, abaxially green suffused with pink to vinaceous. Inflorescences with peduncle 1.1–4.5 cm long, light green to cream-coloured to pale pink; supernumerary bracts present, sometimes absent, when present much narrower than the cincinnus bracts, otherwise similar; cincinnus bracts 1.9–4.8 × 1.9–6.9 cm, subequal to unequal to each other, widely trullate to very widely trullate to rhombic to transversally trullate, conduplicate, overlapping, adaxially light green to green, becoming cream-coloured to light green towards the basal third, pink to vinaceous along the veins and margin, abaxially pink to purplish-pink to vinaceous to purple, becoming cream-coloured to pale pink towards the basal third, vinaceous to purple along the veins and margin, base cuneate to obtuse to truncate, not saccate, apex acute to acuminate; double-cincinni 10–50-flowered; bracteoles with base suffused with light green, apex suffused with pale pink. Flowers with floral buds 2.8–5.5 × 1.2–3.5 mm, light green to white to pale pink; pedicels 0.8–1.7 cm long, white to light green or pale pink to pale reddish-pink; sepals 3.2–5.9 × 1.7–3.6 mm, oblong to lanceolate to ovate, membranous, not dorsally keeled, hyaline to semi-opaque, light green to white to pale pink, apex acute, straight; petals 4.6–8.1 × 4.3–7.8 mm, widely trullate to very widely trullate to rhombic; stamens with filaments 4.4–8.3 mm long, anthers 0.5–0.8 × 0.7–1.3 mm, connective yellow to ochre to orange-yellow, anther sacs red to maroon to brown; ovary 1.3–2.2 × 1.2–1.7 mm, style 1.9–4.7 mm long. Capsules 2.2–4.2 × 1.7–2.8 mm, oblongoid, when immature pink to reddish-pink to vinaceous, becoming tan-coloured when mature. Seeds 1.8–3.7 × 1–1.7 mm, narrowly oblong to oblong-elliptic, sparsely farinose to farinose, farinae white, outer rim conspicuously scrobiculate, ridges continuous to the ones from the central testa, central testa faintly scrobiculate, ridges radiating from the embryotega.

Pollen flattened-convex in equatorial view. Axis P - 17.4 (18.4 ± 0.5) 19.4 × E - 24.4 (32 ± 1) 45.4 µm. Sulcus 26.7 (35.8 ± 0.7) 45.4 × 12.3 (13.9 ± 0.2) 16.2 µm, membrane verrucate-granulate with sparse nanogranules. Sexine ultrasculpture microverrucate-perforate, sparsely rugulate. Exine 1 (1.1 ± 0.1) 1.25 µm thick; tectum tectate-perforate (Fig. 2D–F).

Tradescantia spathacea is restricted in the wild to the Yucatán Peninsula and surrounding areas, occurring in Belize, Guatemala, and Mexico (Campeche, Chiapas, Oaxaca, Quintana Roo, Tabasco, Veracruz, and Yucatán) (Fig. 4). It is naturalised in Cuba, the Antilles, the West Indies, Honduras, Nicaragua, Costa Rica, and Panama, and widely cultivated elsewhere. It is very frequently found growing around ancient Mayan sites, as it was domesticated for the production of purple dye (Standley and Steyermark 1952).

Tradescantia spathacea can be found growing from 0–600 m a.s.l. in lowland to lower montane rainforests, more commonly as terrestrial or rupicolous, but also as an epiphyte.

Tradescantia spathacea flowers and fruits profusely throughout the year if conditions are suitable, especially in cultivation. In the wild, it is most frequently found in bloom and fruit from October to June. Wild forms of T. spathacea flower readily in cultivation, including as indoor container plants, without any apparent requirement for seasonal or environmental triggers. It is strongly to partially self-compatible, with some individuals and populations showing lower pollination success, fruit formation and seed set in selfed flowers. This is supported by cultivation observations by two of us. Plants cultivated by MOOP were found to be highly self-compatible, with over 70% of flowers developing into fruits and consistently setting viable seeds. Alternatively, plants cultivated by AR had a low fruit set rate when in isolation, with fruits producing (0–)1–2 fertile seeds due to abortion.

Commonly known in Mexico (Spanish) as maguey morado and maguey rojo (Campeche, Quintana Roo, and Yucatán).

From the combination of the Greek “σπάθη” (spáthē, meaning “broad blade”) + the suffix “-āceā” (indicating “resemblance” or “similarity”) in reference to the spathe-like cincinnus bracts.

Tradescantia spathacea has a wide EOO (ca 521,395 km²) and AOO (ca 1,328 km²). It is consistently observed in the wild, forming large subpopulations, in addition to being widely cultivated around the world, even becoming slightly invasive in several countries. Thus, following the IUCN (2012) criteria and the IUCN Standards and Petitions Committee (2024) recommendations, we suggest that it be considered Least Concern (LC, criterion B).

MEXICO – Campeche • Hopelchén, Jardín Botánico de Zoh-Laguna a 10 km al N de Xpujil, camino a Dzibachén; 22 Jul. 1996; fl., fr.; P. Alvaro M. 405; MEXU. – Chiapas • Ocosingo, a 12 km al NO del Crucero de Bonampak; 12 Feb. 2003; fl., fr.; G. Aguilar M. & C. Chancayun 5595; MEXU. – Oaxaca • St. Maria Petapa, jardin de Sra. Crisofora; 14 Sep. 1992; fl.; B. Frei 142; FB, MEXU, ZT. – Quintana Roo • Carretera Chetumal-Escárcega, a 4 km de la desviación de Chetumal; 25 Sep. 2004; fl., fr.; R. Duno de Stefano & B. Torke 2017; CICY, MEXU. – Tabasco • Nacajuca, Tapotzinfo cerca de Masateupa, al norte de Nacajuca; 17 Jan. 1979; fl.; A. Martínez & C. Cowan 1891; MEXU. – Veracruz • Cercanias de San Andres Tuxtla; Jun. 1955; fl.; Dr. Sandoval s.n.; MEXU [MEXU no. 6819]. – Yucatán • Izamal, Walls of Cenotes and ruins; Jun. 1916; fl.; G.F. Gaumer et al. 23381; F, MA, MO, US.

BELIZE – Cayo • Near Terra Nova Forest reserve, ca 21 km N of Black Man Eddy Village and the Belize River; 5 Jul. 1995; fl., fr.; D.E. Atha et al. 974; K, NY. – Orange Walk • Honey Camp; Nov. 1928; fl., fr.; C.L. Lundell 101; K, US. – Toledo • Dolores, ca 40 km SW of Punta Gorda; 1 Feb. 1990; fl., fr.; M.J. Balick et al. 2570; NY, US.

GUATEMALA – El Petén • Uaxactún; 23 Apr. 1931; fl., fr.; H.H. Bartlett 12701; MICH, US.

Tradescantia spathacea is likely the most well-known species in the genus, easily recognised by its bromelioid habit, strongly discolourous leaves, axillary inflorescences with large boat-shaped bracts, and small, white flowers barely exserted from the bracts. Pollen grains of T. spathacea are smaller [P - 17.4 (18.4 ± 0.5) 19.4 × E - 24.4 (32 ± 1) 45.4 µm] and flattened-convex, with a longer but narrower sulcus [26.7 (35.8 ± 0.7) 45.4 × 12.3 (13.9 ± 0.2) 16.2 µm], membrane verrucate-granulate with sparse nanogranules, sexine microverrucate-perforate and sparsely rugulate, and generally thinner exine [1 (1.1 ± 0.1) 1.25 µm].

Tradescantia spathacea is one of the oldest cultivated species in the genus. Natural wild forms of the species are now rare in cultivation, and the majority of cultivated specimens belong to the miniature-sized Bantam Group, established here. Most cultivars are selected for their variegated foliage, which seems to display a range of chimeral albino mutations. We accept six cultivars for T. spathacea, with five of these representing miniature forms, for which we establish a new Group.

Cultivation requirements are flexible, and a range of soil types, light levels, and temperatures is tolerated. Container-grown specimens are susceptible to root and stem rot from excess moisture, but are highly tolerant of drought. Growth is rapid, and propagation is easily achieved through stem cuttings, which also results in the production of numerous plantlets below the cut.

Habit same as the wild form; leaves adaxially dark olive-green, with longitudinal yellow stripes, abaxially vinaceous to purple; flowers same as the wild form, except for the sterile pollen; fruits and seeds never produced.

Flowers commonly. However, pollen appears sterile, and seeds are never produced.

Collected in the wild in Quintana Roo (Mexico).

MEXICO – Quintana Roo • Chetumal, 6.5–7 km N of Tomás Garrido on the road which joins Highway 186 W of Nicolas Bravo; 15 Mar. 1990; fl., fr.; A.C. Sanders et al. 9921; US, UCR.

An ICRA decision was made to accept the name ‘Vittata’, despite ‘Variegata’ having priority, since it has become the most universally used name (Brickell et al. 2016, Art. 29.2). Under the ICN (Turland et al. 2025, Art. 38.1), Laurentius (1859: 6) does not meet the basic requirements of the valid publication of T. discolor var. vittata, with the requirements only being met nine years later by Regel (1868: 26), who provided a Latin diagnosis. Nonetheless, under the ICNCP (Brickell et al. 2016, Art. 27.1), the basic requirements for the valid publication of a cultivar name are met. Thus, if the taxon is accepted as a variety, T. discolor var. vittata Laurentius ex Regel is the correct author for this name, with T. discolor var. variegata Hooker (1858: t. 5079) being the earliest available name at the varietal rank. However, the recognition of this taxon as a variety would require a new combination under T. spathacea. Alternatively, if accepted as a cultivar (as in the present study), T. spathacea ‘Vittata’ Laurentius is the correct name and author for this biological entity.

Figure 6. 

Cultivars of Tradescantia spathacea. A–C. T. spathacea ‘Vittata’. A. Habit. B. Upper view of an inflorescence showing two open flowers. C. Detail of a solitary synflorescence. D–H. T. spathacea Bantam Group. D. Habit of T. spathacea ‘Dwarf’. E. Habit of T. spathacea ‘Cream’. F. Habit of T. spathacea ‘HANSOTI02’. G. Habit of T. spathacea ‘Lemon Sunset’. H. Habit of T. spathacea ‘Sitara’. Photographs by Avery Rowe.

Habit much smaller than the wild forms; stems less than 10 mm wide, prostrate; leaves up to 15 × 3 cm; flowers rare, when present, same as the wild forms, except for the brown anther sacs and sterile pollen; fruits and seeds never observed.

Named after the small varieties of domestic fowl (usually of chicken or duck), in reference to the reduced stature of the cultivars in this group. Just like the fowl varieties, members of the T. spathacea Bantam Group are much smaller than the standard-sized wild forms, but otherwise similar in most respects.

A group of cultivars of unknown origin, cultivated since at least 1984.

The Bantam Group currently comprises five accepted cultivars, differentiated based on leaf colouration and variegation patterns. The plants in this group flower very seldom, which is most likely due to their reduced vigour, especially the variegated cultivars (i.e. T. spathacea ‘Cream’, T. spathacea ‘HANSOTI02’, and T. spathacea ‘Sitara’). The T. spathacea Bantam Group is very popular in cultivation, generally grown as groundcover or in containers.

Leaves adaxially green to olive-green, abaxially vinaceous to purple, margins purple when grown under bright light; flowers never observed.

Unknown.

As the name suggests, this cultivar represents a miniaturised form of wild-occurring T. spathacea. The earlier names are rejected because cultivars cannot be named using Latin words (Brickell et al. 2016, Art. 21.11).

Stems cream-coloured or yellow or green or pink, commonly longitudinally striped in one of the other colours; leaves adaxially green to olive-green, with sectoral variegation consisting of cream-coloured to pink stripes, abaxially pinkish-purple to greyish-purple, with pale yellow to cream-coloured stripes mirroring the adaxial cream-coloured to pink stripes; flowers never observed.

Unknown, but cultivated in Europe since at least 2022.

The pattern of variegation is highly plastic, with different leaves ranging from almost entirely green to almost entirely cream-coloured to pink stripes, depending on the number and width of the stripes.

Leaves adaxially dark green, longitudinally striped yellow to lime-green, sometimes so densely striped the leaves look greenish-grey, abaxially pale lavender to pink, margins golden; flowers rare.

Sport mutation discovered by Ashish Hansoti in Mumbai, India, in 2005.

The variegation pattern in the leaves is generally stable but occasionally makes solid-gold sports (i.e. T. spathacea ‘Lemon Sunset’). The colouration of the leaves can become more or less bold depending on lighting conditions. Unpublished trade names include ‘Sitake’s Gold’ (an orth. var. of ‘SITARA GOLD’), ‘Sunny Star’, and ‘Amber Waves’.

Leaves adaxially solid lime-green to golden-yellow, lacking stripes, abaxially pink to light pinkish-purple; flowers rare.

Sport mutation which has arisen independently from T. spathacea ‘HANSOTI02’ on multiple occasions.

Named by Tyleen Mansker after a community vote. In T. spathacea ‘Lemon Sunset’, the variegation characteristic of T. spathacea ‘HANSOTI02’ is lost, giving rise to this cultivar’s evenly coloured leaves.

Leaves adaxially dark yellowish-green to olive-green to greyish-green, with purplish-grey to light purple to pale pink longitudinal stripes, abaxially pink to purple with longitudinal vinaceous stripes mirroring the adaxial stripes; flowers rare.

Sport mutation discovered by Ashish Hansoti in Mumbai, India, in 2002.

The breeder’s chosen name is given priority despite not being established until 2022 (Brickell et al. 2016, Art. 31.4). The pattern of variegation in this cultivar is stable and consistent. However, the stripes can become more or less bold depending on lighting conditions. Unpublished trade names include ‘Bermudensis Variegata’, ‘Pink Lightning’, ‘Purple Flame’, ‘Purple Rain’, ‘Rainbow’, ‘Tricolor Dwarf’, ‘Variegata’, and ‘Versicolor’.