Plectranthus scutellarioides
(coleus)

Identity

Preferred Scientific Name

• Plectranthus scutellarioides (L.) R. Br.

Preferred Common Name

• coleus

Other Scientific Names

• Coleus blumei Benth.
• Coleus blumei var. verschaffeltii (Lem.) Lem.
• Coleus laciniatus (Blume) Benth.
• Coleus scutellarioides (L.) Benth.
• Coleus verschaffeltii Lem.
• Ocimum scutellarioides L.
• Plectranthus blumei (Benth.) Launert
• Plectranthus laciniatus Blume
• Solenostemon scutellarioides (L.) Codd

International Common Names

• English: common coleus; painted nettle; painted-leaf plant; variegated coleus
• Spanish: ahijado; macho; nene
• Chinese: wu cai su; xiao wu cai su; yuan bian zhong

Local Common Names

• Caribbean: Jacob’s coat
• Cook Islands: televete; terevete
• Cuba: manto; orégano francés
• Dominican Republic: tocador
• Fiji: lata; lau lata
• French Polynesia: terevete
• Germany: Buntblatt; Buntnessel
• Haiti: manteau de St. Joseph
• Jamaica: Joseph’s coat; painted nettle
• Japan: niwajiku; saya-bana
• Malaysia: kentongan
• Micronesia, Federated states of: karamat; koaramahd; koionleng; koramahd; koromaht; waruguchá
• New Zealand: pate
• Niue: selevese; televete
• Philippines: dapoyana; lapunaya; malamayana; maliana; mayana; patak dugo; saimayu; taponaya
• Puerto Rico: coleo; nazareno; tocador; verguenza
• Samoa: fateine; la‘au fai sei; pate
• Solomon Islands: asaka
• Sweden: Palettblad
• USA/Hawaii: weleweka

Summary of Invasiveness

P. scutellarioides is a bushy, woody-based evergreen perennial listed as ‘cultivation escape, naturalised, weed’ in the Global Compendium of Weeds (Randall, 2012), and is known to be invasive to Cuba (Oviedo Prieto et al., 2012) and a cultivation escape in Puerto Rico (Liogier and Martorell, 2000), Tonga and Guam (Stone, 1970; PIER, 2014). It is now cultivated pantropically. The species is considered a medicinal plant in many cultures but has also been classed as a narcotic hallucinogen (Duke, 2002). The species is shade tolerant, can grow in a wide range of habitats, reproduces by both seeds and stem cuttings, and can form dense thickets (Wagner et al., 1999; Missouri Botanical Garden, 2014b; PIER, 2014). Research is needed on its impact on ecosystems, as it currently appears to be a minor pest rather than a seriously damaging weed.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Lamiales
•                         Family: Lamiaceae
•                             Genus: Plectranthus
•                                 Species: Plectranthus scutellarioides

Notes on Taxonomy and Nomenclature

The Lamiacae, or mint family, is a family of herbs, shrubs, and trees comprising about 200 genera and 3,200 species, many with a long history of medicinal and food use (University of Hawaii, 2014). This family includes some of the most well-known herbs containing essential oils including lavender, sage, basil, mint and oregano. Many Lamiaceae species have square stems (although square stems are also found in other families), aromatic aerial parts when crushed, simple opposite leaves, and two-lipped flowers.

Plectranthus is a paleotropical genus comprising around 300 species of annual or perennial herbs or subshrubs, often succulent (Wagner and Lorence, 2014). Its name derives from the Greek words ‘plectron’, meaning ‘spur’, and ‘anthos’, meaning ‘flower’, in reference to the spur-shaped flowers of some members of the genus (Stearn, 1992). Because of the lack of clear-cut morphological criteria to discriminate not only among species within the Plectranthus genus but also among the closely related genera, numerous taxonomic problems in the naming of species have resulted in misplacement of species in several closely related genera like Coleus, Solenostemon and Englerastrum (Lukhoba et al., 2006).

The species P. scutellarioides has many cultivars grown as ornamentals due to the showy, variegated leaves, and the species is also known to be used in traditional medicine in various cultures around the world (Hanelt et al., 2001). Its name refers to its perceived similarity to the Scutellaria plant, which has a pouch on the fruiting calyx that resembles a ‘scutella’, a small dish or saucer (Stearn, 1992). This species is placed by some authors in the genus Solenostemon (Wagner and Lorence, 2014).

Description

Perennial herb to 1.5 m high, stems erect or ascending, the branchlets finely pubescent to glabrous. Leaves petiolate, the blade highly variable in size, shape, and colouration, usually brightly coloured or blotched, generally ovate-deltoid to broadly ovate, (1-)4-12(-17) cm long, (1-)3-7(-10) cm wide, truncate to rounded or cuneate and attenuate at base, acute to acuminate at apex, crenate to laciniate at margin, scabrid to subglabrous above, hirtellous on nerves and often over lamina beneath, gland-dotted; petioles 1-5(-8) cm long. Flowers terminal racemes or panicles 5-10(-35) cm long, with flowers in verticils or in irregularly branched and sessile cymes, the inflorescence rachis finely tomentose, the bracts ovate, to 5 mm long and 4 mm wide, long acuminate, deciduous, the pedicels 3-4 mm long; calyx obliquely campanulatae, pubescent and gland-dotted, 10-nerved, to 7 mm long in fruit, the upper lip erect, ovate, 2-4 mm long, 2-3 mm wide, rounded to acute at apex, the lateral teeth broadly oblong, truncate to rounded, 0.5-1.5 mm long, the lowermost teeth connate to form a strap-shaped lobe to 4 mm long in fruit, divided at apex; corolla blue to purple or mauve, infundibular, 8-13(-18) mm long, the tube paler, usually about 5 mm long, puberulent, abruptly recurved, the upper lip 1.5 mm long, erect, the lower lip deeply concave, to 6 mm long; filaments of stamens usually united 1-2 mm at base, included with style by lower lip of corolla. Fruit, nutlets lenticular to broadly ovoid or subglobose, 0.75-1.2 mm long, brown, glossy. [Wagner and Lorence, 2014]

Distribution

P. scutellarioides is considered native to continental southeastern Asia southward to Malesia and northern Australia. It is cultivated in tropical and temperate regions around the world including all parts of China, and is invasive in some places (Hanelt et al., 2001; Gargiullo et al., 2008; Acevedo-Rodriguez and Strong, 2012; Flora of China Editorial Committee, 2014; Wagner and Lorence, 2014).

In the New World, this is the only species of Plectranthus that occurs in Costa Rica (Gargiullo et al., 2008).

Although it is cultivated around the world, P. scutellarioides is not included in some major references such as the Flora Europaea (Royal Botanic Garden Edinburgh, 2014), Funk et al.’s (2007) work on the Guiana Shield, or Forzza et al.’s (2010) work on Brazil.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

P. scutellarioides is considered native to Southeast Asia, New Guinea and northern Australia. It was introduced to other parts of Asia including the Philippines, the Marshall Islands, and various parts of Asia-Pacific (Merrill, 1923; Velde, 2003), as well as to the New World for cultivation as a medicinal, ornamental and culinary plant, and is now pantropical. Date of the species’ introduction to the West Indies is uncertain but it may have occurred around the turn of the twenthieth century. It was not included in Bello’s flora of Puerto Rico (1881; 1883) but was present in the Antilles by 1911, as it was included in volume 4 of Ignatiuz Urban’s work on the Antilles (1898-1928) (as syn. Coleus laciniatus). It was in Puerto Rico by 1924 (Britton and Wilson, 1924), and various Coleus species were reportedly being cultivated as ornamentals in Bermuda by 1918 for their variegated leaves (Britton, 1918).

In Asia-Pacific, P. scutellarioides was introduced to the Philippines by 1923 (Merrill, 1923) and is a more recent introduction to the Marshall Islands, where it is still considered a rare species (Velde, 2003).

Risk of Introduction

P. scutellarioides has been reported as invasive to Cuba (as syn. Coleus scutellarioides) (Oviedo Prieto et al., 2012) and as a cultivation escape in Guam and Tonga (PIER, 2014) as well as Puerto Rico (Liogier and Martorell, 2000). It has been introduced beyond its native range due to its popularity as a cultivated ornamental and medicinal plant, and likely spreads by human activity, garden waste, water, and soil movement, as it can reproduce by both seeds and cuttings (Missouri Botanical Garden, 2014b). It can form dense thickets and occurs in a range of habitats including disturbed urban areas, forests, fields, riverbanks, and wild bushlands (Flora of China Editorial Committee, 2014; PIER, 2014). Considering its known ability to escape cultivation, this species poses risk of introduction especially near areas where it is cultivated, although further research is needed to assess its impact on the environment and native flora. 

Habitat

P. scutellarioides occurs in a range of habitats. In Australia, it grows in monsoon forest, beach forest and in disturbed areas in rain forest (CANBR, 2014) and in Hawaii it occurs in disturbed parts of mesic to wet forest (Wagner et al., 1999). In China and Taiwan the species has been reported to occur in stream sides, open areas, hills, fields, and forests (Flora of China Editorial Committee, 2014). In Asia-Pacific, P. scutellarioides has been observed growing in dense patches occasionally along roadsides in Niue, and in Papua New Guinea as a garden cultivation and in the wild in bush margins and grasslands (PIER, 2014).

Habitat List

Biology and Ecology

Reproductive Biology

P. scutellarioides propagates by seed (PIER, 2014), but is capable of regenerating from cuttings (Missouri Botanical Garden, 2014b).

Environmental Requirements

P. scutellarioides is winter hardy to USDA zones 10-11 and grows in moist, organically rich, loose soils in part shade, although it can tolerate full shade and some recently developed cultivars can tolerate full sun (Missouri Botanical Garden, 2014b).

P. scutellarioides grows at low elevation ranges. In Hawaii it has been reported growing between 30 and 3000 m (Wagner et al., 1999), while Australia it occurs from near sea level to 1000 m (CANBR, 2014), and in Bolivia it has been recorded for 0-500 and 1000-1500 m in lowland rainforest and Yungas vegetation zones (Bolivia Checklist, 2014). In Nicaragua it has been found to occur at 50-950 m (Flora of Nicaragua, 2014).

Climate

Notes on Natural Enemies

P. scutellarioides has no serious insect or disease problems, although aphids, spider mites and whiteflies may prey on plant parts (Missouri Botanical Garden, 2014b).

Means of Movement and Dispersal

P. scutellarioides is a popular cultivated species and has been intentionally introduced around the world for use as an ornamental and medicinal plant. It has also been unintentionally introduced, as it is known to have escaped from cultivation and naturalized in many places (Randall, 2012; Flora of Nicaragua, 2014; PIER, 2014).

The species is likely spread by soil and water movement and by garden waste, as it can reproduce by both seeds and vegetative cuttings (Missouri Botanical Garden, 2014b), is extensively cultivated, and is known to grow near streams (Flora of China Editorial Committee, 2014). 

Impact Summary

Environmental Impact

P. scutellarioides is known to be invasive or naturalized to many places where it has been introduced, including Cuba and parts of the Pacific islands (Oviedo Prieto et al., 2012; PIER, 2014). The species is a perennial weed and reportedly can form dense patches (PIER, 2014), but could be a minor pest; more research is needed on the extent of its’ impact on ecosystems where it is invasive, and its potential threat to the native flora.

Risk and Impact Factors

• Proved invasive outside its native range
• Abundant in its native range
• Highly adaptable to different environments
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Tolerant of shade
• Long lived
• Has propagules that can remain viable for more than one year
• Reproduces asexually

• Causes allergic responses

• Highly likely to be transported internationally deliberately

Uses

Many cultivars of P. scutellarioides are grown around the world as ornamentals, due to the species’ showy, variegated leaves. In Papua New Guinea, it is used as a food additive, while in Southeast Asia it is considered a medicinal plant and used to treat a variety of ailments including dyspepsia, ophthalmia, and wound infections (Hanelt et al., 2001; Duke, 2002). P. scutellarioides been classed as a narcotic hallucinogen (Duke, 2002), and in southern parts of Mexico it is considered magical and is used in divination (Hanelt et al., 2001). In Java, the species is used as a living fence in coffee plantations (Hanelt et al., 2001).

Gaps in Knowledge/Research Needs

Further research is needed to assess the extent of this species’ invasiveness and its impact on environments. Currently it poses a risk of introduction due to its widespread cultivation and continued popularity as an ornamental, and its history as a cultivation escape and weed. P. scutellarioides could be a minor introduced pest, but research is recommended to determine whether there are more serious repercussions to its introduction to ecosystems.

References

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Links to Websites

Contributors

23/08/2014 Original text by:

Marianne Jennifer Datiles, Department of Botany-Smithsonian NMNH, Washington DC, USA

Pedro Acevedo-Rodríguez, Department of Botany-Smithsonian NMNH, Washington DC, USA

Distribution Maps