Common Name: Palmarosa Grass

General Information

Cymbopogon martini is an evergreen, tufted, aromatic grass with numerous erect culms arising from a short, stout, woody rhizome[]. The stems are up to 3 metres tall[].
The plant has been gathered from the wild since antiquity, and this method still produces an important portion of the essential oil. However, the plant has also been cultivated since the beginning of the 20th Century and is now grown in several areas of the tropics[]. Palmarosa oil has gradually lost importance in the world market, being replaced by low-cost synthetic or natural geraniol[]. The natural oil is still preferred in high quality perfumes, however, especially in the Middle East[].

Known Hazards

None known

Botanical References

Range

E. Asia - Indian subcontinent.

Habitat

Not known

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Perennial
Height	2.50 m
Pollinators	Wind
Self-fertile	No
Cultivation Status	Cultivated, Wild

Cultivation Details

Palmarosa is a plant of the semi-arid to moist tropical and subtropical lowlands[]. It occurs naturally and in cultivation in India from 12 - 32°N and has been grown successfully from between the latitudes of 5 - 32° on either side of the equator[310. It is grown at elevations between 150 - 1,200 metres[]. It can succeed with an annual rainfall below 600 mm, but requires about 750 mm annual rainfall for a reasonable single harvest and at least 1500 mm if it is to be harvested more frequently[]. It prefers warm and sunny conditions with average daily temperatures of 20 - 25°c; temperatures of 25 - 30°c for extended periods can significantly reduce yields and suppress flowering[]. Frost causes damage at all growth stages and at higher elevations aboveground plant parts may die back during the cool season[]. Even slight frost at harvesting can be devastating and may reduce yields by half[].
In its natural habitat this species grows on poor, often slightly alkaline soils (pH 7.5 - 8.5) of sandy-loamy to loamy texture. Soils rich in organic matter and nitrogen are reported to yield high quality oil. It can also succeed on slightly saline soils[]. In cultivation, fertile well-drained soils of pH 6 - 7 are considered optimum. On alkaline soils (pH 8.5 or higher) growth and yields are reduced, but oil quality is not affected[]. It does not tolerate acid soils or waterlogging[].
Long days seem to favour oil production, both in quantity and in geraniol content[].
There are two forms of this species and these hybridize spontaneously in the wild wherever their habitats overlap. They are very similar to look at but differ considerably in the essential oil they produce:-
Var martini. Known as Palmarosa or Motia. A diploid form, the essential oil has a floral rosy smell and a geraniol content of up to 95%[]. It grows in scattered patches; habitat dry and sunny[].
Var sofia. Known as Gingergrass or Sofia. A tetraploid form, the essential oil has a turpentine-like aroma and a geraniol content of up to 65%[]. It grows in dense masses; its habitat is wetter and less sunny[]. See the separate record for more information on this plant.
The plant grows naturally in round clumps or tussocks. It is strongly cross-pollinated and wild stands are highly variable[].
Several cultivars yielding high quality oil have been developed[, ].
New plantations should be weeded several times, but an established crop quickly smothers most weeds after being harvested[]. Yields tend to decline rapidly if the plants are not fertilized regularly: in India herbage yields fell from 11.5 t/ha in the first and second year to 8.4 t/ha in the 4th year and 4.1 t/ha in the 7th year, while oil content fell from 1.5 g to 0.8 g per 100 g fresh matter[]. The plant has a life span in cultivation of 10 - 15 years, but many plantations become unprofitable after 6 - 7 years[].
Plants should be harvested when they are flowering, the oil content of the flowers is highest after opening and drops dramatically after flowering[].
The first harvest can be taken about 6 months after planting; the number of subsequent harvests per year depends on temperature and water availability with up to 4 harvests per year possible in some areas[].
The time of harvesting affects oil yield and quality. Harvesting during the rainy season gives high herbage and oil yields, but low geraniol content, while during the dry season herbage and oil yield are lower and geraniol content higher[].
The height of cutting is generally 20 cm above the ground. Cutting high leaves a substantial stubble, so reducing the cost of harvesting and distillation, but cutting low stimulates regrowth of the crop[].
Well managed plantations produce annual herbage yields of 10 - 15 t/ha, giving 50 - 100 kg oil. Improved cultivars may yield up to 25 t/ha of herbage producing 150 kg oil[].

Edible Uses

The essential oil is used to flavour ice cream, gelatin desserts, chewing gum and bakery products[].

Medicinal

In traditional medicine both the plant and its oils are used to treat rheumatism, hair loss, arthritis, lumbago and spasms[].

The essential oil is a strong fungicide[]. In laboratory tests it was more effective than several synthetic fungicides against 9 pathogenic fungi and yeasts, including Aspergillus spp., Candida albicans, Monilia sitophila and Trichophyton tonsurae[].

Agroforestry Uses:

The plant is grown extensively to control erosion on erodible hillsides and to stabilize edges of terraces and gullies[].

Other Uses

An essential oil, called palmarosa oil, is obtained from the flowering tops[]. It is used in perfumes, for soaps and cosmetics, and for flavouring tobacco and liqueurs[]. It is also an important source of natural geraniol, which is an excellent extender in many floral, rose-like perfume compounds and a starting material for the production of aroma chemicals, notably geranyl esters that have a lasting rose-like aroma[].
All aboveground parts of the plant contain essential oil, the oil content of the flowers being higher than that of the stems and leaves. The oil content in high-yielding selections grown under optimum conditions can reach 0.5 - 1.5%; the average yield from traditional stills, however, is only 0.2 - 0.3% (both on a fresh weight basis)[].
Palmarosa oil is a pale yellow or pale olive liquid with a sweet, floral-rosy odour with variable top notes and undertones depending on the quality and age of the oil; notes of rye bread, tea and clary sage have also been reported. Chemically, palmarosa oil consists mainly of geraniol and geranyl acetate and smaller amounts of linalool, farnesol, nerol, 'ALFA'-humulene and terpineols. In soap perfumes palmarosa oil shows great tenacity, much greater than commercial geraniol obtained from other sources, e.g. citronella oil. It blends well with most soap perfume compounds and forms an excellent perfume base with geranium oil and oakmoss absolute. Palmarosa oil from Indonesia has a significantly higher geranyl acetate content than Indian oil. This is due not only to differences in growing conditions, but also to the use of more modern distilleries. In the United States, palmarosa oil is 'generally recognized as safe' (GRAS No 2831)[].

The essential oil is an active component of mosquito repellents[].

Propagation

Seed - on a small scale the seed is sown in trays, on a larger scale it can be sown in nursery beds. Only just cover the seeds and make sure it does not dry out. The tiny seeds are often mixed with fine sand to obtain even distribution, and the mixture is then beaten to detach the glumes and improve germination rates. Healthy seed germinates 10 - 20 days after sowing and seedlings are ready for transplanting in 6 - 8 weeks when 15 - 20 cm tall[]. The plant grows vigorously, so seedlings should be planted singly[].
Care should be taken to use pure seed of var. martini, in particular in India and Pakistan where natural stands often are mixtures of var. martini and var. sofia[].
Propagation by offshoots and cuttings is also possible, but there are indications that seedlings yield more herbage and oil[].

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