Common name: Palmarosa

Palmarosa is an aromatic grass originating from the Indian subcontinent, its native range extending across subtropical and tropical regions of India and Pakistan. Nowadays, it has a wider distribution due to its cultivation for its rose-scented essential oil, which is used as a fragrance in the perfume, pharmaceutical and tobacco industries.

There are two varieties in cultivation, Palmarosa grass (var. motia), which comes from the Deccan tablelands of Central India, and Ginger grass (var. sofia), which is adapted to humid tropical lowland climates. The following description applies only to Palmarosa grass, which produces the more superior and commercially valuable essential oil.

It is a tall perennial clumping grass, reaching 1.8 to 2.6 m (6 to 9 ft) tall and made up of erect, closely arranged stems sprouting from underground rhizomes. Stems typically grass-like, with slender leaf sheaths at the base holding above them prominently mid-ribbed, green sword-shaped leaves up to 50 cm (1.5 ft) long and 1 to 3 cm (0.4 to 1.2 in) wide.

In autumn, the plant produces multiple, erect flowering spikes topped with a narrow, flowering panicle up to 30 cm (12 in) in height. These hold small, insignificant flowers which, after pollination, are followed by tiny seed.

Use 

The above-ground parts of the plant are harvested and steam distilled to recover the essential oil, which is traded as 'Palmarosa oil', 'Turkish geranium oil' or 'Rusa oil'. It is a colourless to pale yellow oil with a sweet, delicate rose aroma due to its high Geraniol content (more than 70%). 

Palmarosa oil is used extensively in the fragrance industry, particularly for scenting tobacco as well as soap products, for which it is suited owing to its long-lasting rose notes and ability to remain stable in contact with alkalis.  

Health use

Rusa oil is used in its native range as an external treatment for stiff joints and skin disease. An infusion of the leaves is prescribed as a stimulant and as a relief for flatulence.

Climate

Grows naturally and produces herbage with a high oil content in sub-humid to moderately humid subtropical and tropical climates, generally frost-free areas with annual lows of 13 to 25°C, annual highs of 26 to 35°C, annual rainfall of 800 to 1600 mm and a dry season of 2 to 6 months, extending to 12 months with irrigation.  

Growing

New plants are usually started from divisions, made by dividing mature plants into smaller pieces for planting, which is done at the start of the rainy season. Plants can also be raised from seed, either sown in containers or broadcast on prepared soil.

Performs best on free-draining clay, loam and sand soils of a slightly acid to alkaline nature, generally with a pH of 6.0 to 8.0, and on sites with full sun exposure. 

It is intolerant of slow-draining or waterlogged soils but has good tolerance to drought and moderately saline soil conditions.

The above-ground parts are harvested when the plant is in full bloom and before it has set seed, which is when the oil content is at its highest. There is usually only one harvest in the first year followed by two or three harvests in subsequent years, depending on the growing conditions. Plants remain productive for up to eight years, but in commercial plantations are replaced after four years, which is when their oil content starts to decline.

Yields for irrigated crops range from 6,000 to 10,000 kilograms of fresh herbage per hectare per year and with an average oil content of 0.25% yields 150 to 250 kilograms of oil, or the equivalent of 134 to 223 lbs per acre. Yields of oil from rain-fed crops are about one-third that of irrigated crops.

Problem features

The tiny seed are easily dispersed by wind or water. It is listed as a weed in at least one reference publication and is recorded as having naturalised in Australia but there does not appear to be any record of it as a serious weed. It is assessed as a low weed risk for Hawaii by The Hawaii Pacific Weed Risk Assessment (HPWRA) project.

The essential oil is believed to be as toxic as other essential oils, causing illness after ingestion and can be fatal in large quantities. 

Books

• Brady, G. S. & Clauser, H. R & Vaccari, J. A. 2002, Materials handbook : an encyclopedia for managers, technical professionals, purchasing and production managers, technicians and supervisors, 15th ed., McGraw-Hill, New York

• Council of Scientific and Industrial Research (India) 1948 - 1976 (11 volumes), The Wealth of India : a dictionary of Indian raw materials and industrial products, Delhi

• Debboun, M. & Frances, S. P. & Strickman, D. 2006, Insect repellents : principles, methods, and uses, CRC Press, Boca Raton, Florida

• Dey, S.C. 1996, Fragrant flowers for homes and gardens, trade and industry, Abhinav Publications, New Delhi, India

• Farooqi, A. A. & Sreeramu, B. S. 2004, Cultivation of medicinal and aromatic crops, Hyderabad University Press, Hyderabad

• Lis-Balchin, Maria 2006, Aromatherapy science : a guide for healthcare professionals, Pharmaceutical Press, London

• Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London

• National Institute of Industrial Research (India) 2005, Cultivation of tropical, subtropical vegetables, spices, medicinal, and aromatic plants, Delhi, India

• Parrotta, J. A. 2001, Healing plants of peninsular India, CABI Publishing, Wallingford, Oxfordshire

• Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

• Randall, R. P. 2007, The introduced flora of Australia and its weed status, Cooperative Research Centre for Australian Weed Management, Glen Osmond, South Australia

• Winter, R. 2009, A consumer's dictionary of cosmetic ingredients : complete information about the harmful and desirable ingredients found in cosmetics and cosmeceuticals, 7th ed, Three Rivers Press, New York

Articles, Journals, Reports and Working Papers

• Dagar, J. C. & Singh, G. 2007, Biodiversity of Saline and Waterlogged Environments: Documentation, Utilization and Management, NBA Scientific Bulletin, (9), 78.