Close-up views:

The young plants:

| Last updated: November 2022 |

The overall appearance of this plant resembles that of the Indian Borage (Coleus amboinicus). One feature that differentiate them is the characteristic of the stem. Coleus monostachyus has a 4-angled stem while that of Indian Borage is round. Some matured plants seemed to have nodules among its roots. Additionally, it seemed that Indian Borage rarely bears flowers in Singapore while Plectranthus monostachyus can be seen flowering all the time under sunny condition.

The synonym Solenostemon monostachyus is used more often when referring to this herb. The transferred of Solenostemon monostachyus to Plectranthus monostachyus was described in a publication by Kew in 2001 [1]. In 2019, the accepted botanical name changed again, this time round to Coleus monostachyus [2].

The first time that I came across this herbaceous plant in Singapore was in 2007 at Sungei Buloh Wetland Reserve, around the then outdoor classroom area. A large population could be seen thriving on a deserted plot. Since then, I started to see more of them in other open areas. It was first reported in Malaysia back in 2003 [3] while only reported recently in India [4].

The plant was not listed in the Singapore flora checklist published in 2009. The official status of this herb in Singapore was finally established in a local publication in 2015 [5]. Interestingly, Indian Borage (Plectranthus amboinicus) mentioned in the same article was also not listed in the 2009 plant checklist although it is a common cultivated herb here.

In the iNaturalist website viewed on 10 November 2022, there were 54 observations from Singapore with the earliest sighting dated in March 2014.

References:

[1] Pollard BJ, Paton A. A New Rheophytic Species of Plectranthus L'Her. (Labiatae) from the Gulf of Guinea. Kew Bulletin 2001;56(4):975-982. | Read preview |

[2] Paton AJ, Mwanyambo M, Govaerts RHA, Smitha K, Suddee S, Phillipson PB, Wilson TC, Forster PI, Culham A. Nomenclatural changes in Coleus and Plectranthus (Lamiaceae): a tale of more than two genera. PhytoKeys 2019;129:1-158. | Read article |

[3] Kiew R, Kamin I. Coleus (Lamiaceae) in Peninsular Malaysia including two new species. PhytoKeys 2021;186:93-110. | Read article |

[4] Prasad SK, Biju P, Thomas AK, Josekutty EJ. Coleus monostachyus (P. Beauv.) A. J. Paton (Lamiaceae): A new addition to the flora of India. Plant Sci Today 2022;9(sp1):9-11. | Read article |

[5] Chung YS, Teo S, Chong KY, Kurukulasuriya BR, Tan HTW. Weed risk assessments of the exotic species of Plectranthus L'Her. (Lamiaceae) in Singapore. Nature in Singapore 2015;8:1-13. | Read article |

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[2018] Ohwofasa IT, Okwena Pondei J. Synergistic effect of the extracts of Vernonia amygdalina and Solenostemon monostachyus on gram-negative bacteria. Pak J Biol Sci 2018;21(8):369-375.

[2016] Okokon J, Davis KA, Azare BA. Antipyretic and antimalarial activities of Solenostemon monostachyus. Pharm Biol 2016;54(4):648-653.

[2016] Okokon JF, Davis K, Nwidu LL. Anti-inflammatory and antinociceptive activities of Solenostemon monostachyus aerial part extract in mice. Avicenna J Phytomed 2016;6(3):284-294. | Read article |

[2012] Afolabi IS, Osikoya IO, Fajimi OD, Usoro PI, Ogunleye DO, Bisi-Adeniyi T, Adeyemi AO, Adekeye BT. Solenostemon monostachyus, Ipomoea involucrata and Carica papaya seed oil versus Glutathione, or Vernonia amygdalina: methanolic extracts of novel plants for the management of sickle cell anemia disease. BMC Complement Altern Med 2012;12:262. | Read article |

[2012] Okoko T, Ere D. Antioxidant activities of Solenostemon monostachyus leaf extract using in vitro methods. Sci Res Assays 2012;7:621. | Read article |

[2012] Fidele KZ, Andre KB, Yao DJ, Michel OA. Action of hydroethanolic leaves extract of Solenostemon monostachyus (lamiaceae) on cardiovascular system of mammalians: blood pressure lowering effects. Int J Pharm Bio Sci 2012;2(3):310-320. | Read article |