Plectranthus amboinicus

Plectranthus amboinicus

Indian borage or country borage, French thyme, Indian mint, Mexican mint, Cuban oregano, soup mint, Spanish thyme (Plectranthus amboinicus (Lour.) Spreng., 1825) is a herbaceous species belonging to the Lamiaceae family

Systematic –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Plantae,
Division Magnoliophyta,
Class Magnoliopsida,
Subclass Asteridae,
Lamiales Order,
Lamiaceae family,
Ocimeae tribe,
Subtribe Plectranthinae,
Genus Plectranthus,
Species P. amboinicus.
The terms are synonymous:
– Coleus amboinicus Lour.;
– Coleus amboinicus var. amboinicus;
– Coleus amboinicus var. violaceus Gürke;
– Coleus aromaticus Benth.;
– Coleus carnosus Hassk.;
– Coleus crassifolius Benth.;
– Coleus subfrutectosus Summerh.;
– Coleus suborbicularis Zoll. & Moritzi;
– Coleus suganda Blanco;
– Coleus vaalae (Forssk.) Deflers;
– Majana amboinica (Lour.) Kuntze;
– Majana carnosa (Hassk.) Kuntze;
– Majana suganda (Blanco) Kuntze;
– Ocimum vaalae Forssk..

Etymology –
The term Plectranthus comes from the Greek “πλῆκτρον” (plectron), i.e. plectrum, a small sheet of ivory or other almond-shaped material which was used to pluck the strings of the lyre, and “ἄνθος” (anthos), i.e. flower, in reference to shape of the back part of the corolla.
The specific epithet amboinicus comes from the Latin “amboinicus, a, um”, that is, from Amboina, an island in Indonesia, hypothetical place of origin.

Geographic Distribution and Habitat –
Plectranthus amboinicus is a plant native to an area that includes: Angola, Burundi, India, Kenya, KwaZulu-Natal, Mozambique, Swaziland and Yemen.
From southern Africa it would have been transported by Arabs and other traders to Arabia, India and Southeast Asia along the maritime trade routes of the Indian Ocean. The plant currently also grows in mainland India. The plant was later brought to Europe, and then from Spain to the Americas, hence the name Spanish thyme.
Its natural habitat is that of coastal woods or bushes, on rocky slopes and clay or sandy plains at low temperatures; it is also found along roadsides, abandoned places and river banks; at altitudes up to 1,500 meters.

Description –
Plectranthus amboinicus is a plant that grows up to 1 m in height.
It has a fleshy stem, about 30–90 cm, with long, stiff hairs (bristly villous) or densely covered with soft, short and erect hairs (tomentose). Old stems are smooth (glabrescent).
The leaves are oval, 5–7 cm by 4–6 cm (1.6–2.4 in), fleshy, undivided (simple), broad, with a tapering tip (ovate). The margins are coarsely crenate or dentate-crenate except at the base. They are thickly covered with (pubescent) hair, with the lower surface having the most glandular hairs, giving them a frosted appearance. The petiole measures 2–4.5 cm. The aroma of the leaves can be described as a pungent combination of the aromas of oregano, thyme and turpentine. The flavor of the leaves is described as similar to oregano, but with a strong mint-like flavor.
The flowers are formed on a short stem (slightly pedunculated), pale purple in color, in dense flowering whorls (cymes) of 10-20 (or more), at distant intervals, in a long and thin spike-shaped raceme. The rachis is 10–20 cm, fleshy and pubescent. The bracts are broadly ovate, 3–4 cm long, acute. The calyx is bell-shaped, 2–4 mm long, hirsute and glandular, with 5 equal lower teeth, broadly ovate-oblong, obtuse, sharply acute upper tooth, acute lateral and lower teeth. The corolla is blue, curved and declined, 8–12 mm (0.31–0.47 in) long, tube 3–4 mm long, enlarged trumpet-shaped; limb bilabrous, upper lip short, erect, puberulent, lower lip long, concave. The filaments are fused underneath into a tube around the style.
The fruit is a light brown, roundish, flattened tetrachenium, approximately 0.7 x 0.5 mm.

Cultivation –
Plectranthus amboinicus is an attractive, evergreen perennial that is harvested from the wild, primarily for local use as food and medicine. It is sometimes grown as an ornamental and also for medicinal uses and for its edible leaves, which are particularly popular in Mexico and some parts of the Caribbean.
It is a plant that grows in an area ranging from warm temperate areas with dry and mild winters to tropical areas with dry and humid climates.
It grows best in areas where annual daytime temperatures are between 22 and 28°C, but can tolerate 10-36°C.
It prefers an average annual rainfall between 2,000 and 2,600 mm, but tolerates 700 – 4,000 mm.
It prefers exposure in full sun or shade and, from a pedological point of view, prefers fertile, well-drained soil in partial shade; grows best in light soil with a pH between 6 and 6.5, tolerating 5 – 7.
The plant is widely cultivated for ornamentation, food and medicine. Sometimes it escapes cultivation and naturalizes on disturbed soil.
It can form dense mats in dry, shaded forests and is thought to be invasive on some Pacific islands.
In general, however, it is a widely spread plant in tropical and subtropical countries both as an ornamental and for culinary uses in family gardens. Easy to cultivate and fast growing, it can be cultivated in tropical and subtropical climate areas, as it cannot tolerate temperatures around 0 °C, unless dry and for a very short period; it requires full sun and is not particularly demanding regarding the soil, even poor, as long as it is well drained and cannot tolerate water stagnation. Usable for borders, as a ground cover and in rock gardens with moderate watering, allowing the upper layer of soil to dry before watering again; well rooted it can withstand long periods of drought. Frequently grown in pots, especially for culinary uses and to be able to be sheltered in the colder months, where the climate does not allow it to be outdoors, in a bright position, such as a south-facing window, with winter minimum temperatures not lower than 10° C and moderate and spaced watering, so as to allow the substratum to partially dry, almost suspended in the presence of low temperatures.
Several variegated varieties have been selected for ornamental purposes.
Reproduction occurs by seed, which must be placed on the surface on a sandy substrate kept slightly humid at a temperature of 22-24 °C, with germination times of 1-3 months, but usually and easily by apical cutting in summer and by division in spring .

Customs and Traditions –
Some Plectranthus species are difficult to identify due to the lack of clear morphological criteria to discriminate not only between species within the genus but also between closely related genera. This has resulted in numerous taxonomic problems in species naming, resulting in species often being placed in several closely related genera such as Coleus, Solenostemon, and Englerastrum. Furthermore, some species formally placed in Plectranthus, are now recognized as the more distantly related genus Isodon.
Because of these taxonomic problems, different names have often been used for the same Plectranthus species and thus it has been difficult to gather information on the ethnobotanical uses of this genus. Furthermore, the most commonly used medicinal Plectranthus species have a high degree of synonymy.
This plant is known by various common names, including: country-borage, cuban-oregano, five-in-one, french-thyme, indian-borage, indian-mint, mexican-mint, sour-mint, soup- mint, spanish-thyme (English); dao shou xiang, zuo shou xiang (Chinese); coléus d’Afrique, oreille (French); patharcur, patta ajavayin (Hindi); daun kucing, daun kambing (Indonesian); karpuravalli (Sanskrit); orégano, orégano brujo, orégano de Cartagena, orégano de la hoja ancha, orégano de la tierra, oregano francés, orégano poleo, toronjil de limón (Spanish); cubanischer oregano, jamaika-thymian (German); hom duan huu suea, niam huu suea (Thai); can day la, rau cang (Vietnamese).
Traditional medicine has attributed various properties to this plant which it has used, for example, to relieve epilepsy attacks, insomnia, as a disinfectant, antifungal and muscle stimulant. Recently, scientific research has multiplied on its action1 and its toxicity. It was shown that 100 mg tablets of P. amboinicus caused smooth muscle contraction in guinea pigs.
The fresh leaves are widely used, particularly in Caribbean and South-East Asian cuisine, to flavor meat and fish dishes, for sauces, soups and salads, in India they are also eaten fried, the aroma is usually described as intermediate between thyme (Thymus vulgaris L., 1753) and oregano (Origanum vulgare L., 1753).
The leaves are strongly flavoured. The herb is used as a substitute for oregano to mask the strong odors and flavors of fish, mutton, and goat. The fresh leaves are used to perfume laundry and hair. It is also grown as an ornamental plant. In the southern Indian state of Karnataka, it is fried in batter to make pakodas. The leaves can be used to prepare rasam and a herbal remedy (kashayam) that offers symptomatic relief from colds and colds.
The plant also occupies an important place in traditional medicine for various digestive, respiratory and neurological pathologies; the essential oil extracted from the leaves is attributed with anti-inflammatory, antioxidant, larvicidal and antimicrobial properties.
The main chemical compounds present in Coleus amboinicus essential oil are carvacrol (28.65%), thymol (21.66%), α-humulene (9.67%), undecanal (8.29%), γ-terpinene (7.76%), p-cymene (6.46%), caryophyllene oxide (5.85%), α-terpineol (3.28%) and β-selinene (2.01%).[17] Another analysis obtained thymol (41.3%), carvacrol (13.25%), 1,8-cineole (5.45%), eugenol (4.40%), caryophyllene (4.20%), terpinolene (3.75%), α-pinene (3.20%), β-pinene (2.50%), methyl eugenol (2.10%) and β-phellandrene (1.90%). Variations can be attributed to the methodology used in the extraction process, seasonal variations, soil type, climate, genetic and geographic variations of the plant.

Preparation Method –
Plectranthus amboinicus is a plant used for both food and medicinal purposes. It can be harvested throughout the growing season for use fresh, dried or frozen.
The leaves are eaten cooked or raw. They have an aroma similar to oregano and are occasionally used as a potherb and sometimes eaten raw with bread and butter.
They are most commonly used as a seasoning in recipes that call for mixed herbs or oregano and to spice dishes containing tomato sauces.
The leaves can be chopped, made into flour balls and fried in oil. They have a very strong and aromatic flavor, so use sparingly.
In the medicinal field it is a strongly aromatic herb with a flavor similar to sage.
It is known to reduce inflammation, although little else is known about its effects.
The antibacterial and antiseptic properties of the plant have been attributed to the presence of numerous compounds in the plant, including carvacrol, codeine, flavones, phenols, tannins, and aromatic acids.
The leaves have been found to possess bronchodilator activity and anti-Mycobacterium tuberculosis activity.
The plant has also been shown to have antimicrobial activity and is believed to have antiviral activity against Herpes simplex virus-1 and anti-HIV inhibitory activity.
The leaves are said to be antibacterial, antitussive and fever-reducing.
They are taken internally in the treatment of a variety of digestive problems such as dyspepsia, indigestion, diarrhea and flatulence.
To treat coughs, an infusion or syrup made from aromatic leaves is prescribed.
The leaves are also used to treat a wide range of other ailments including epilepsy, seizures, meningitis, heart, heart failure, fevers, colds, bronchitis, asthma, cholera, menstrual pain, labor pain, delayed labor, post-operative pain. partum and to facilitate the expulsion of the placenta.
The leaves are often used in the treatment of urinary diseases in the Amazon and India. This species is also said to relieve kidney problems, treat vaginal discharge and is drunk after childbirth.
Applied externally, the leaves are used to treat headaches, inflammation, skin allergies, wounds, burns, sores and ulcers.
Rubbed into the skin, they will bring quick relief to bites and stings.
The seed oil is a treatment for acute edematous otitis in Polynesia, while in India its leaves are rubbed on the eyes to relieve conjunctivitis.
The plant possesses cytotoxic and anticancer activity and can be used in the treatment of cancer.
The plant is used to treat snake bites.
The plant is anti-inflammatory and is used to treat stiff neck and back pain.
Among other things, fresh spicy leaves are used to perfume laundry and hair.
The leaves are rubbed into the hair and body after bathing.
Preparations of the leaves can be used to wash clothes and hair.
The leaves are rubbed on the body to act as an insect repellent.
An essential oil obtained from the plant is rich in carvacrol and is used medicinally.
The essential oil obtained from the leaves and stems is used as a skin conditioner in commercial cosmetic preparations.

Guido Bissanti

Sources
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora d’Italia, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.

Photo source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/335720708/original.jpg

Attention: Pharmaceutical applications and food uses are indicated for informational purposes only, they do not represent in any way a medical prescription; we therefore decline any responsibility for their use for healing, aesthetic or food purposes.