Pogostemon plectranthoides (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Pogostemon plectranthoides Desf.

Family: Labiatae

• Mentha secunda Roxb.

• Thekkali (En, India), rudilo (En, Nepal)
• Thailand: niam nguang chaang (central), om (northern).

Throughout the Indian subcontinent from Tamil Nadu to Nepal and Bangladesh, but not in Sri Lanka. Cultivated occasionally, in the Russian Federation commercially.

A kind of patchouli oil is distilled from the leaves, which, especially in the Russian Federation, is used as a substitute for the true patchouli oil of P. cablin (Blanco) Benth. In the Indian subcontinent P. plectranthoides is used similarly to P. benghalensis (Burm.f.) Kuntze.

• Semi-shrub, up to 3 m tall with a solid, angular stem.
• Leaves opposite, tomentose; petiole up to 3 cm long; blade ovate, up to 15 cm × 7 cm, base rounded, margin double dentate, apex acute.
• Inflorescence a verticillaster, arranged into a terminal false spike about 6 cm long with more than 2 lateral spikes; bracts broadly ovate, about 6 mm × 3 mm.
• Calyx inflated, tubular, about 5 mm long, hairy outside, glabrous inside, with 5 ciliate teeth about 1 mm long; corolla tubular, up to 8 mm long, purple, 2-lipped, upper lip 3-lobed; filaments 4, up to 8.5 mm long, purple, inserted at different heights in the corolla tube, lowest one at 3.5 mm height, hairy but glabrous towards the base; style 1 cm long, purple, ending in 2 lobes about 1.2 mm long.
• Fruit composed of 4 nutlets; nutlet obovoid, 0.6 mm × 0.5 mm, finely punctate.

P. plectranthoides is a very common constituent of the ground flora of Terminalia woodland and open bush vegetation in India. In the Russian Federation it is cultivated as an annual and the crop is harvested once a year by cutting at ground level and drying. Subsequently the oil is obtained by distillation. Little information is available on the oil. Prospects for South-East Asia should be investigated.

• Raza Bhatti, G. & Ingrouille, M., 1997. Systematics of Pogostemon (Labiatae). Bulletin of the Natural History Museum London (Botany) 27: 77-147.
• Weiss, E.A., 1997. Essential oil crops. CAB International, Wallingford, United Kingdom. 600 pp.

P.C.M. Jansen