Plectranthus rotundifolius (Poir.) Spreng.

Last updated: 29 July 2015

Scientific Name

Plectranthus rotundifolius (Poir.) Spreng.

Synonyms

Calchas parviflorus (Benth.) P.V.Heath, Coleus dysentericus Baker, Coleus pallidiflorus A.Chev., Coleus parviflorus Benth., Coleus rehmannii Briq., Coleus rotundifolius (Poir.) A.Chev. & Perrot, Coleus rotundifolius var. nigra A.Chev., Coleus rugosus Benth., Coleus salagensis Gürke, Coleus ternatus (Sims) A.Chev., Coleus tuberosus (Blume) Benth., Germanea rotundifolia Poir., Majana tuberosa (Blume) Kuntze, Nepeta madagascariensis Lam., Plectranthus coppinii Heckel, Plectranthus coppinii Cornu, Plectranthus ternatus Sims, Plectranthus tuberosus Blume, Solenostemon rotundifolius (Poir.) J.K.Morton [1]

Vernacular Name

Malaysia Ubi kembili, ubi keeling [2]
English Madagascar potato, Hausa potato, country potato [2]
Indonesia kentang ireng (Javanese); huwi kentang (Sundanese); kentang Jawa [2]
Thailand Man-khinu, man-nu (Southern) [2]
France Pomme de terre de Madagascar [2].

Geographical Distributions

Plectranthus rotundifolius is thought to lie in Madagascar or tropical Africa, but at present it is only known from cultivation. It is frequently cultivated in Madagascar, tropical and Southern Africa, Sri Lanka, India, throughout continental Asia to Peninsular Malaysia, Sumatra, Java, the Moluccas and possibly in the Philippines. [2]

P. rotundifolius is preferably grown in the tropical high rainfall lowlands, rarely up to 1000 m altitude. [2]

Botanical Description

P. rotundifolius is a member of the Labiatae family. It is a perennial, aromatic, semi-succulent herb that can grow up to 1 m tall and is cultivated as an annual. [2]

The stem is decumbent or ascending, quadrangular, with densely pubescent on the angles and roots at the nodes. [2]

The leaves are rather thick, juicy, faintly aromatic when bruised and arranged oppositely. The petiole is 1-3(-5) cm long and puberulous. The blade is ovate to sub-orbicular, measuring 2-6 cm x 1.5-4 cm, wedge-shaped at the base, coarsely crenate at the margins, puberulous at the apex and with gland-dotted below. [2]

The inflorescence is a terminal false spike, measures 5-15 cm long and with verticillasters of 4-6 flowers. The pedicel is 1-2 mm long. The bracts are small. The sepal is bell-shaped, measures 1.5-3 mm long, glandular-hispid and with 5-toothed. The upper tooth is oblong, acute and very short median teeth with rounded apex while the lower teeth is highly connate that forms an almost truncate apex but ends abruptly in 2 widely apart acute tips. The petal is tubular and 2-lipped, measures 7-12 mm long, light to dark violet, pubescent and with gland-dotted. The tube is strongly curved. The upper lip is very short and with 4-lobed while the lower lip is boat-shaped. There are 4 stamens that curved within the lower lip. They are up to 2.5 mm long, shortly unite at the base and envelope the style. The style is with 2-fid and slightly exceeding the stamens. [2]

The roots produce ovoid to oblongoid sessile potato-like tubers, measuring up to 4.5 cm x 1.5 cm, blackish, brownish, reddish-grey or whitish and with rough skin. [2]

Cultivation

The P. rotundifolius tuber development favour the evenly distributed rainfall and low night temperature. The crop cannot stand waterlogging. Well-drained sandy loams are preferred, but heavy clays are unsuitable. In Southeast Asia, it is often planted on dry rice fields after rice. [2]

Chemical Constituent

No documentation

Plant Part Used

No documentation

Traditional Use

No documentation

Preclinical Data

No documentation

Clinical Data

No documentation

Dosage

No documentation

Poisonous Management

No documentation

Line drawing

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Figure 1: The line drawing P. rotundifolius [2]

References

  1. The Plant List. Ver 1.1. Plectranthus rotundifolius (Poir.) Spreng. [homepage on the Internet]. c2013. [updated 2012 Mar 23; cited 2015 Jul 29]. Available from: http://www.theplantlist.org/tpl1.1/record/kew-158453
  2. Plectranthus rotundifolius (Poiret) Sprengel. In: Flach M, Rumawas F, editors. Plant Resources of South-East Asia No. 9: Plants yielding non-seed carbohydrates. Leiden, Netherlands: Backhuys Publishers; 1996.